ICEG2D_An Integrated Software Package for Automated ... - CiteSeerX

NASA

/ CR--2000-209914

ICEG2D_An Automated

Integrated Software Package Prediction of Flow Fields for

Single-Element

David

S. Thompson

Mississippi

State

February

2000

and University,

Airfoils

Bharat

With

K. Soni

Mississippi

State,

Mississippi

Ice Accretion

for

The NASA STI Program

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Information

NASA/CR--2000-209914

ICEG2D_An Automated

Integrated Software Package Prediction of Flow Fields for

Single-Element

David

S. Thompson

Mississippi

Prepared

State

under

National

and

Bharat

University,

Grant

Aeronautics

Space

Administration

Glenn

Research

February

Airfoils

Center

2000

and

K. Soni

Mississippi

NAG3-2235

With

State,

Mississippi

Ice Accretion

for

Available NASA Center 7121 Standard

for Aerospace Drive

Hanover, MD 21076 Price Code: A04

Information

from National

Technical

Information

Service

5285 Port Royal Road Springfield, VA 22100 Price Code: A04

Table of Contents Page Table of Contents

iii iv

List of Figures List of Tables 1. Introduction

V"

2. The ICEG2D Software Package 2.1 General Overview 2.2 Installation 2.3 The ICEG2D Framework 2.4 The ICEG2D Interface 3. Module ICE_DIST_2D 3.1 ICE_DIST_2D Input 3.2 Merging and Pruning Algorithms 3.3 Internal Surface Description 3.4 Surface Point Distribution 3.5 3.6 4. Module 4.1 4.2 4.3 4.4 4.5

5.

6.

7. 8. 9.

Demonstration of Distribution Algorithm ICE_DIST_2D Output ICE_GRID_2D ICE_GRID_2D Input Blocking Strategies Wake Cut Definition Normal Distance Distribution Parabolic Grid Generation 4.5.1 Reference Grid Definition

4.5.2 Grid Smoothing 4.6 Demonstration of ICE_GRID_2D 4.7 ICE_GRID_2D Output NPARC Specific Modules 5.1 Input for NPARC_INPUT and NPARC_RESTART 5.2 NPARC_INPUT Output 5.3 NPARC_RESTART Output Grid Quality Assessment 6.1 Comparison of Computed Results with Experimental 6.1.1 The Clean Airfoil 6.1.2 Case 622EXP 6.1.3 Case 623EXP 6.2 Validation of ICEG2D Examples Summary References

Ill

Data

1 3 3 4 5 6 9 9 10 11 14 16 19 21 21 22 23 23 24 25 25 27 31 33 33 33 36 37 37 37 40 44 47 49 53 55

List of Figures Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure

1. Demonstration of Merging Algorithm 2. Merging in Region Near Horn/Upper Surface Intersection 3. Demonstration of Pruning Algorithm 4. Nomenclature for NURBS Description of Iced Airfoil 5. Effect of Smoothing on Normalized Weight Function 6. Effect of Clustering Parameter on Normalized Weight Function 7. 204LEW Surface Distribution 8. 904EXP Surface Distribution 9. 204LEW Airfoil Grid 10. 11. 12. 13.

Nose Region of 204LEW Airfoil Grid 204LEW Airfoil Grid - Double Block 204LEW Airfoil Grid - Double Block 904EXP Airfoil Grid

14. 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. 25. 26. 27. 28. 29. 30.

904EXP NLF0441 NLF0441 NLF0441 NLF0441 622EXP 622EXP 622EXP 622EXP 622EXP 622EXP 622EXP 623EXP 623EXP 623EXP 623EXP Automatic

Airfoil Grid - Concave Region Clean Airfoil- Grid Dimensions 329x101 Pressure Distribution -Angle of Attack 12 deg. Section Lift Coefficient versus Angle of Attack Section Drag Coefficient versus Angle of Attack - Grid Dimensions 529x101 Grid in Region Near Nose Section Lift Coefficient versus Angle of Attack Section Drag Coefficient versus Angle of Attack Pressure Distribution - Angle of Attack 3 deg. Pressure Distribution - Angle of Attack 3 deg. Pressure Distribution - Angle of Attack 9 deg. - Grid Dimensions 699x101 Grid in Region Near Nose Section Lift Coefficient versus Angle of Attack Pressure Distribution - Angle of Attack 3 deg. Regridding for Simulated Ice Growth

iv

Page 12 12 13 13 17 18 18 19 28 28 29 29 30 30 38 38 39 39 41 41 42 42 43 43 44 45 45 46 46 52

List of Tables Table Table Table Table Table Table Table Table Table Table Table Table

1.Functions of ICEG2D Interface 2. Default File Extensions 3. Namelist DISTRIBUTION Variables 4. Namelist GRID_PARAMETERS Variables 5. Namelist NUMBER_OF_BLOCKS Variables 6. Namelist BLOCK_PARAMETERS Variables 7. Namelist BLOCK_PARAMETERS Variables 8. Namelist TITLES Variables 9. Namelist INPUTS Variables 10. Namelist TURBIN Variables 11. Namelist SEQDT Variables 12. Namelist BLOCK Variables

- Single-Block - Double-Block

Grid Grid

Page 3 5 10 21 22 22 22 34 34 35 35 35

1.

Introduction

Prediction

of ice accretion

degradation

is a long-term

and

development

fluid

dynamics

objective

program

of the effort airfoil

The

was

data

executed interactive

was

written

with

ice

in Perl

the execution

definition

module,

for a given

a FORTRAN90

package

developed

airfoil

is accomplished

(with the weight function remainder of the airfoil.

as

using

curvature)

The grid module, ICE_GRID_2D, was developed from a previously defined surface distribution. FORTRAN90

with a C driver

single-

modules

and double-block to generate

routine

the NPARC

namelist

language

was written from

of the ICEG2D is an assessment

solutions computed using the automatically (NASA GRC data for NLF0414 [8]). In

the

sections

procedure, Procedures

that

follow,

the

technology

and a description of the operation used to validate the software package

be

in

an

surface in C with

GGLib

of points

algebraic

can or

a discrete

- a

on the

in the iced

region

stretching

for the

to generate a nearly orthogonal grid ICE_GRID_2D was written in grid generation

can be generated input

file

and

NPARC

employed

grids

with

restart

developed.

software package has been of grid quality by comparison generated

scheme

[3-

automatically.

NPARC_INPUT and NPARC_RESTART respectively, were modules were written in FORTRAN90 with C driver routines.

A preliminary validation Included in the validation

to associate

ICEG2D

algorithm

and uses a parabolic

grid topologies

modules.

distribution and

is a

ICEG2D,

routines

an equidistribution

on surface

of the

Below

of directives

NURBS

the

single-

program,

to generate

[2]. Automatic

for

1999).

modules.

ICE_DIST_2D

utilizes

to perform

component

a scripting

developed

configuration. and

30,

driver

a vocabulary

the directives line prompt.

at MSU

based

the

program

routine

library

uses

2D, was

iced airfoil

geometry/grid surface

and

with

first-year

that the "fn'st year"

and the various

of appropriate

ICE_DIST

namelist

along

The

automatically

be noted

research

to computational

accretion.

solutions

It should

to the framework

in batch mode using mode from a command

The geometry

The

related

a software

[1]

developed

as the interface

interface

7]. Both

issues

with

validate

with ice accretion.

framework

serves

external

and

NPARC

performance

To this end, a three-year

to address

components

to develop

to generate

and the resulting

was nine months in length (March 1 - November of the activities accomplished to date:

software

which

initiated

for aircraft

geometries

grant actually brief summary

The

of icing research.

has been

was

necessary

configuration

objective

simulations

preprocessing element

on a full aircraft

of the software package are also discussed.

the are

Both

performed. of NPARC

experimental

in ICEG2D,

file,

data

installation discussed.

J

2.

The ICEG2D Software Package

2.1

General

The

Overview

ICEG2D

software

preprocessing flow

fields

tasks around

package

necessary single-element

solver NPARC [1]. ICEG2D performed to generate the CFD a Perl program basic functions

was

includes solutions.

Generate discrete airfoil surface

definition

with

automatically fluid

ice accretion

using

of file associations

grid

the

simulations

the

and directives

structured

to perform

of flow are is

the five

Details The surface definition iced airfoil definition, definition,

Generate

perform

dynamic

a framework in which various operations The user interface to the ICEG2D framework

Module ICE_DIST_2D

of

to

computational

airfoils

that utilizes a system shown in Table 1.

Function

developed

to generate

module takes the the clean airfoil

and default or user-specified

parameters to generate the grid ready, point distribution defining the iced airfoil. The grid generation module takes the iced airfoil surface definition and default or

ICE_GRID_2D

user-specified parameters and blocking specification to generate a nearly orthogonal grid. Generate

NPARC

input file

NPARC_INPUT

This module generates an NPARC namelist input file using the generated grid and a user-defined namelist file.

Generate

NPARC

restart

NPARC_RESTART

This module generates an NPARC restart file using the generated grid and a userdefined namelist file.

Generate

CFD solution

file

A batch process can be started to run an NPARC solution using the input and restart files.

Table

There

are also directives

I. Functions

that execute

of ICEG2D

external

Interface

procedures

to perform

auxiliary

tasks.

For

example, FAST [9] can be used to plot the surface distribution or the grid using "display distribution" or "display grid" respectively. A listing of the ICEG2D directives and a brief description of each directive are included in Section 2.4. Based was

on discussions decided

with NASA

to minimize

the

personnel

input

of automation, ICEG2D

various

parameters

used

to generate

are

the

the surface

a text file containing

it

may

be

a stream

of

directives is used as input via redirection. In the interactive mode, the user ICEG2D and issues directives from a command line within a Unix shell. Further of ICEG2D

mode,

the context ICEG2D.

in batch

automation

In batch

to run

ICEG2D executes

the

mode.

and within

needed

executed

enhancing

or interactive

GRC user

FORTRAN distribution

namelists and

that

the grid.

define

The

the

namelist

variableshavebeenassigneddefaultvaluesthat shouldwork for a wide variety of iced airfoil applications. A typical ICEG2D sessionconsistsof taking an iced airfoil definition, available from LEWICE [10] or IRT data [11], and a clean airfoil definition as input to the module ICE_DIST_2Dto generatea discretesurfacedistribution. The surface definition is then used The

as initial grid

data

is used

modules

for the

along

to generate

grid generation

with

a problem

an NPARC

restart

module, definition

2.2

to generate

file" as input input

a grid.

to appropriate

file. Finally,

an NPARC

It should be noted that the process could be data files are available and have been defined

with modularity in mind. Module parts or entire requiring significant changes to the framework.

modules

can be

Installation

Installation

The

namelist

file and an NPARC

solution is started as a background process. initiated at any point provided the necessary appropriately within the ICEG2D framework.

ICEG2D was designed easily replaced without

ICE_GRID_2D,

of ICEG2D

can be accomplished

by following

these steps:

1. 2.

Unzip the gzipped file using "gunzip ICEG2D.tar.gz" Untar the file using "tar -xvf ICEG2D.tar"

3.

Execute

executable

respective compiled.

"Install_ICEG2D" "Install_ICEG2D"

compiles

and

links

directories. Note: Warnings will occur This is normal and does not affect execution

During installation, nine subdirectories directories and their contents are given ,

2.

examples geometry

3.

grid_gen

- ICE_GRID

help_files

- help file

5.

nparc_gen modules

parameter_files

8.

script_files

9.

report

within

the ICEG2D

library

example

ICEG2D

their

is

being

directory.

The

cases

for NPARC_INPUT

- FORTRAN - contains

- contains

directory

as the NURBS of the code.

in

and NPARC_RESTART

- GGLib

7.

These

modules

2D modules

- two subdirectories

nurbs_lib

various

in the main

- four subdirectories containing - ICE_DIST_2D module

4.

,

are created below:

the

names

must

script

namelist

files for display

this document be left

flies directive

as a pdf file

unaltered

because

framework.

4

of internal

file

associations

made

To execute

ICEG2D,

the following

setenv

ICEG2D_DIR

setenv

NPARC_DIR

set path = ($path setenv

four lines must be included

(path to directory (path

to directory

in your .cshrc

where

ICEG2D

is located)

where

nparc2ds

is located)

file:

$ICEG2D_DIR)

TRAP_FPE

"ALL=COUNT;UNDERF_ZERO;

OVERFL=IEEE,TRACE(5),ABORT(100);

DIVZERO=ABORT;

INVALID=TRACE(1),ABORT(1)" The first two lines

define

environment

variables

and

where

the

executable,

the

directory

includes

the ICEG2D

directory

floating point exceptions automatic mode. 2.3

The

The

ICEG2D

ICEG2D

association output

file

treated

and

nparc2ds,

$path

variable.

is important

is based

names.

The

on a system

primary

the modules.

These

of internal

association

a set of automatically

Extension

Data

.cln

Clean airfoil

.dat .dst

Iced airfoil

fourth

error

The

directory third

line

line defines

trapping

how

in the

fully

is the

defined

file names

associations

with

case._name.

file names are defined

or

By defining

is utilized using

default

case_name

containing framework.

the

for input the

and

and

default

input input distribution

Number

of points,

Real (x,y) data pairs

Number

of points,

Real (x,y) data pairs

Plot3d

formatted

Plot3d

unformatted

r,

.inp .rst

NPARC NPARC

input file restart file

FORTRAN FORTRAN

.out

NPARC

standard

ASCII

output Table

are

2. Default

data, multizone,

2d

data, multizone,

2d

namelist file unformatted file

File Extensions

nine FORTRAN namelists used to define The default namelist files are located

parameters in the

used by directory

$ICEG2D_DIR/parameter_files: .

The file containing with

dist._parm.file)

surface_type distribution

a

file

Format

Airfoil point Grid file

Additionally, there ICEG2D modules.

ICEG2D

is located. The

for

default extension based on the file type. Below is a table extensions and their associated file types used in the ICEG2D

.grd

the main

Framework

case_name,

to and from

in the shell

are

framework

user-prescribed

NPARC

that specify

data for the FORTRAN is either

association of points

namelist

dist_smooth.ini

or a user-defined

on the iced airfoil

surface.

DISTRIBUTION

or dist_rough.ini f'de.

These

parameters

(associated based

on

control

the the

The

.

file

for

(associated

namelists

with block..parm_file)

or a user defined The

°

file. These

file for namelist

grid_gemini process. The

o

NUMBER_OF_BLOCKS

TURBIN,

used

SEQDT,

defined

in the and

NPARC_Info.npc

parameters

define

BLOCK

parameters

with

these

associations

Minimally,

the user

definition

file. Default

default

values

examined

were

to date.

namelist

variables.

containing

may

must

provide

values

In some

2.4

ICEG2D

The

The

ICEG2D

the

user

are

definition

files and make

the course

[ 1] for a description

of these

one

directive

provides

must

a series

of associations

start in the first column,

case letters

must

case sensitive.

In the descriptions

the data entries

appear

1.

.

# - Indicates def(ine) •

mode

of the

The modified

The

directive.

user is referred

to

Interface

framework

or lower

or more

files.

[directive - action] [object - what the directive producesacts

upper

These

for the cases

ICEG2D

between

internal

external files. Some associations are created automatically while others the ICEG2G directives. The ICEG2D directives all have the same form:

Each

directives.

ICEG2D.

modifications.

solution.

make

files into the directory

the appropriate

of the NPARC

file.

and

effective

to modify

the necessary

file using

file

defined

and the problem

within

proven

is to copy the needed

with the internal during

desire

files

INPUTS,

definition

ICEG2D

input

defined

and have

may

procedure

files are generated manual

cases,

airfoil

user

directory

appropriate

clean

by trial and error

a

local

is

the grid generation

problem or

the

grid._parm_fiIe)

- TITLES,

in the

to

using

and

The suggested

the airfoil

the NPARC

changed

the iced

control

definition

contained

for all parameters

determined

file can then be associated Other

be

scheme. with

nparc_info_file)

Typically, the user will copy this file modifications appropriate for the problem. Again,

the blocking

problem

- are

(associated

or double_block.ini

(associated

file. These

NPARC

BLOCK_PARAMETERS

single_block.ini

GRID_PARAMETERS

or a user

namelists

is either

and

in Italics.

be used below,

that a comment

- defines

are defined

using

must be no leading

the directives

and the objects. and objects

appearing

A # is needed

blanks.

appear

in parentheses

Either

File names in bold

are

while

are optional.

for each line of the comment

something

mode_type

The program

i.e., there

follows.

and

on] [additional info (if needed)]

for the directives

Also, characters

data

[int(eractive)

or bat(ch)

with interactive

will exit if an error is encountered

6

in batch

being

mode]

the default.

•

surface

surface_type

the default respectively.]

case_name

[identifier

iced__geom case_name.dat]

•

clean__geom case_name.cln]

•

dist dist_file

•

dist._parm

•

grid

•

grid_parrn grid..parm_file [file containing default grid parameter file grid._gen.ini]

•

block_parm gridblock_file [file containing blocking default single-block definition using single_bloek.ini,

[distribution dist__parm_file

definition definition

restart NPARC_restart_file case name.rst]

•

input

•

output NPARC_output_file case_name, out]

[NPARC

grid - generates input

•

restart

•

solution

- generates - generates

NPARC NPARC

restart

displays

Is - executes

the Unix

or "default"

parameters, "double"

or "default"

to use

to use

"single" for for default the

default

define

flight

definition)]

restart

output

actually

do

using

defined

file

used

file default file

anything

to

name,

default

default

other

than

smoothed

weight

information

file

file definition command

function

associations

"Is -la"

(uses FAST)

used in distribution

(uses

is

define

information

distribution

is

is case_name.inp] name,

something

weight

current

or "default"

as a batch job

•

- shows

is

input file

dist(ribution) - displays surface grid - displays grid (uses FAST)

show

default

surface_type]

grid parameters

input file name,

distribution

• •

- displays

parameters

file for the specified

[NPARC

grid using defined

- runs NPARC

- graphically

is

something

- generates

•

name,

default

is case_name.grd]

block

not

name,

file

distribution

[NPARC

directive does to ICEG2D.

- generates

•

default

Sets

is case_name.dst]

[NPARC information is NPARC_lnfo.npc]

NPARC_input_file

dist(ribution)

display

parameter

(used to reset

•

"define" internal

default

double_block.ini,

nparc NPARC_info_file conditions, etc., default

•

6.

distribution

file

geometry

[file containing

[grid f'de name,

the default.

or dist._rough.hal

associations]

geometry

[clean

file name,

•

gen(erate)

[iced

clean_geom_file

grid_file

Note: The associations

used for default

iced_.geom.file

being

to dist._smooth.ini

•

single-block

.

with smooth

file

ease

double-block

.

or rough

parameter

•

to use the default

3.

[smooth

distribution

xmgr)

7.

help - displays

8.

exit, quit, bye - exits ICG2D

Additional

*

The

features

user

already surface •

of ICEG2D

start

exists, the distribution

Results name

can

a help message

of each based

at any

part

•

as well as the generated The program generates mode

case#1,

redirected

mode,

of ICEG2D

SysPrompt%

txt

output SysPr0mpt%

of the process.

of the process

on the case name

In the interactive

where

step

user can start the process and then generate the grid.

•

The batch

include:

ICEG2D

are saved

or by specification

the user can display

by

example, specifying

automatically of the name the distribution

grid in a pop-up window with translate a history file in ICEG2D.HST is invoked


case#1.out

the ICEG2D

interactive

mode

directives

and

is invoked

using

case#3..

Out is the

ICEG2D

and entering the ICEG2D directives from the ICEG2D batch and interactive modes are included in Section 7.

prompt.

Sample

ICEG2D also prints informational messages to stdout indicating which effect, etc. Also printed are responses to the various ICEG2D directives.

sessions

for the

associations

are in

3.

Module ICE_DIST_2D

The

quality

of the

simulation. software

package,

airfoil

surface.

surface

surface

airfoil

i.e., smooth module

with

generated

[13],

In [12], the number

complexity,

a high

as possible

curvature

ensures

during

the

is designed

curve.

When

number

success

points

of a CFD an interactive

on a given

be decreased

surface

iced

to reduce

smoothing

airfoil

the

to the

on the surface,

representation

does

some

been

airfoil

surface

of high time

definition. as a NURBS

is present

due

discontinuities

surface description [14]. However, this smoothing is present representation is used to describe the geometry and is not a function

as

At no

internally

slope

from

in regions

smoothing

not reproduce

have

surface

definition.

is represented

for an

experimentally

points

surface

applied

surface

may

an acceptable

Clustering

iced

definition

definition

[10] or obtained

of points.

the airfoil

surface

here is to represent

of the

are distributed

the NURBS

distribute

a grid-ready

as LEWICE

fidelity

below,

ultimate

et. al. [12] used

could

The

employed

is any explicit

the points

the fact that

to generate

such

for a given

as discussed

and

points

of automation.

program

geometric

process

However,

to smooth

of control

the IRT [11]. The basic philosophy faithfully

to the Chung,

the surface.

degree

by an analysis

is critical

true for iced airfoils.

TURBO-GRD

The ICE_DIST_2D iced

distribution

This is particularly

to

in the

once a NURBS of the distribution

algorithm. The

module

library. the

ICE_DIST_2D

ICEG2D

iced

passes

airfoil

is written four

input

file,

file names the

distribution,

and the distribution

associations

made

described

along

within with

ICE_DIST_2D

The input namelist

the

employed

clean

pairs

defining

airfoil

surface.

The

described similarly

below. The clean with the integer

defined

airfoil

followed definition

starting

and

is an ASCII

file names

file are

for

the

surface

using

the

for the module

distribute

using

the

defined

the input

to automatically

data

to merge

points

is

on

ICEG2D

airfoil number

may file, of

at the trailing

be a full edge

the iced airfoil

containing

the

directive

by

(x,y) data pairs definition.

on the lower

surface

a file for

the

number

of points (x,y)

data

a full,

closed

airfoil

clean

airfoil

data is

data with full,

associated with points employed

airfoil

parameters

n_points_iced

not represent

airfoil

definition,

with iced_geom_file

of the integer

followed

or may iced

the

file, associated

file consisting

partial,

by n_points_clean must

a file

definition

(n_points_iced)

definition

The algorithm

clean

[2] geometry/grid to ICE_DIST_2D:

output

that follow,

of a file containing

definition,

definition.

(n_points_clean)

the

is executed

The iced airfoil

surface

the

used

GGLib

line arguments file,

file. These

In the sections

consists

framework,

in the

parameter

the

Input

DISTRIBUTION.

in the ICEG2D

input

ICE_DIST_2D

for ICE_DIST_2D

containing

utilizes

as command airfoil

methodology

airfoil surface. The module "generate distribution." 3.1

clean

ICEG2D.

the

in C and

clean_geom_file, in the surface defining

the clean

In

files,

both

proceeding

the

is defined definition airfoil.

The

surface

clockwise

is

to the

trailing

edge

on the upper

first and last points placed at the average Input

parameters

The namelist default

The trailing

edge point

must

be repeated

used in the surface are listed

distribution

is associated

in Table

are defined

with

dist_.parm_fiIe.

3 and are described

Variable

using

in detail

a FORTRAN The

namelist.

variables

and their

in the appropriate

dist_smooth.ini

section.

dist_rough.ini 1.0

prune order

1.0 3

3

Iower..surface_split_point

0.4

0.4

upper_surface_split_point

O.1

O.1

rpower

6.0

8.0

n_points_a__lower._ region

61

61

n_points_nose_region

151

251

n_points_ a__upper_region

101

101

2000

4000

n_smooth

200

800

cluster

2.0

2.0

max_rain_ratio

5.0

5.0

0.005

0.005

int_max

delta_s_te Table 3.2

Merging

and Pruning

3. Namelist

DISTRIBUTION

Variables

Algorithms

Data from the IRT is obtained in terms of partial iced airfoil shapes necessary to devise an algorithm to merge partial iced airfoil data definition twists

to obtain

or loops

a complete

in which

the merging

1) The locations surface used ensure

and

that the merging

The merging airfoil

these

surface

there

airfoil

algorithm definition

issues

must

closest

is termed

where

be specified. purely

It should

no significant

here is based

to the two endpoints

contains

onto itself.

pruning.

Both

algorithms

that must be addressed: airfoil

should

between

be noted

be merged

the partial

iced

that the approaches

The primary

objective

is to

discontinuities.

on identifying of the partial

Once these two points are located, one for each endpoint, surface at each endpoint is used to estimate the intersection

10

often

back

the transitions

on heuristics,

data

loops

issues

the iced

[15]. It is therefore with a clean airfoil

airfoil

actually

are two primary

definition

introduces

implemented

loops

used to form

are based

process

the iced

the surface

undesirable

algorithm,

surface

Additionally,

describing

and 2) the curves

the clean

to address

these

on the clean

must be determined

airfoil.

the curve

Here, the operation removing are described below.

In developing

as the

in the fide. If the trailing edge is not closed, the trailing edge point is position of the upper and lower surface trailing edge location.

DISTRIBUTION

values

Namelist

surface.

the points iced

airfoil

in the clean def'mition.

the slope of the iced airfoil of the ice surface with the

clean

airfoil

surface.

The

clean

points. C 1 continuous Hermite between the two surfaces.

Figure

1 shows

to IRT data

examples

created

the figure,

the transition

intersection transition The

and maintains

algorithm

the observation

and

that when

denoted

as case

surface

is smooth. surface

the surface

the intersection

occurs

transition

definition

904EXP

A close

corresponding

[17]. This

definition.

curves

case was

As can be seen

up of the region

is shown

in Figure

from

near the

2. Again,

the

continuity.

on heuristics.

"looping"

between

surface

a full surface

the upper

is also based

deleted

for a merged

from

on the lower

is then

[16] is then used to generate

section

points

the horn

is smooth

pruning

airfoil

by deleting

between

surface

of the transitions

for the GLC305

artificially

airfoil

interpolation

The

basis

the following

for the pruning

inequality

algorithm

is

is satisfied:

_ 1 where

{3 is a proportionality

parameter

prune.

The

point,

ri+k, is closer

based

on the distance

eliminates Figure

shows

corresponds described

above

states

under

to the adjacent contained

a

to the here

of O(1)

equation

to the point

the points 3

constant

IRT

generates

point,

data

Once

Intemal

Surface

a full surface

be generated. NURBS NURBS

denoted

if a nonadjacent

13=1.

904EXP

definition

tolerance

implemented

that is

here

simply

ri+k.

using

as case

surface

namelist

[17].

from

The

surface

definition

The

pruning

algorithm

a clearly

have not yet been be significant.

unacceptable

surface.

However,

it seems

quantified.

Description

description

Routines

representation curve is given

is a concern

ri, than a specified

ri+l. The algorithm

generated

At this time, the effects of the pruning unlikely that any negative effects would 3.3

looping

the loop ri through

surface

a usable

that

via the DISTRIBUTION

consideration,

within

pruned

defined

from for by

is obtained,

an internal

the geometry/grid the

iced

airfoil

representation

library surface.

GGLib The

of the surface

[2] are used

parametric

must

to define

description

a

of the

P(u) = (x(u); y(u)) where

u is the parametric

NURBS approximation. points needed to produce single requires

variable.

The

An inversion the specified

most time-consuming less than one minute

element

namelist

order defines

variable

the order

of the

routine from GGLib is used to compute the control surface. It should be noted that this inversion is the of the process

on typical

workstations.

11

aside

from the CFD

Using

another

solution

GGLib

itself

routine,

but the

0.15

i x----X

Merged

Iced airfoil definition

• Partial iced airfoil data definition :_ Clean

airfoil definition

0.05

>-

-0.05

-°'1_0.05

0.05

Figure

0.'15

1. Demonstration

of Merging

0.25

Algorithm

0.015

Merged

iced airfoil

definition

• Partial iced airfoil data definition :_ Clean airfoil definition

0.01

>-

o 0.005

D o

0 0

i 0.005

i 0,0i

0.015

X

Figure

2. Merging

in Region

Near Horn/Upper

12

Surface

Intersection

--0"01

t

I

i

,

• Pruned data Digitized

IRT tracing

-0.03

-0.04

-0.05

I

-0"060.I

NURBS

description

region

PN (u),

variables locations points

I

0.11

Figure

3. Demonstration

is then

split into three

and the aft upper

surface

lower_surface_soit_point on the lower should

Since

runback

angle

of attack,

leading edge each segment

and upper

be defined usually

such occurs

the upper

I

0.12

and

parts

Pu (u)

- the aft lower - based

respectively

than the lower surface are described below.

on the split split

lower

point point.

surface

PL(U),

the nose

on the DISTRIBUTION

as shown is contained

surface

when

is typically The

0.15

Algorithm

upper_surface_soit_point

surfaces

only

0.14

of Pruning

that the ice accretion

surface

I

0.13

which

4. These

the nose

the airfoil

set significantly

methods

closer

used to distribute

,.==b.

Figure

Aft lower surface region

4. Nomenclature

for NURBS

13

Description

of Iced Airfoil

to the

points

Aft upper surface region

Lower surface split point

split

region.

is at positive

Upper surface split point

Nose region

x/c

represent

in Figure within

namelist

in

3.4

Surface

The

first

points

Distribution

step in distributing

to be used on each

of points way,

Point

be a function

a larger

points segment.

ice accretion

dist_rough.ini

with

DISTRIBUTION The number iced

airfoil

namelist

of points surface

is defined

using

here is to make

that

points.

the number

of

the total number

describes

the iced

airfoil.

In this

Currently,

the only mechanism

to

in which the length of the curve does not change surface rough" directive. This directive associates the

dist_.parm_file. for smooth

(si_)

more

is to determine

used

of the curve

The

default

and rough

on the iced airfoil

length

surface

The philosophy

of the length

account for a "jagged" surface significantly is to use the "define file

on the airfoil

surface

to the clean

airfoil

"x [ niced ,nclean

values

for

the

surfaces

are shown

is based

on a function

surface

length

variables

in Table

in the

3.

of the ratio

of the

(Sclea_)

,_rpower

/=[ Siced / ) _,Sclean )

where

nclea n = n_points

aft lower_region

mower is specified

and

+ n_points_aft_upper_region

via the DISTRIBUTION

+ n_points_nose_region

namelist.

To accommodate

used to generate double-block grids, nieed is automatically monitored odd number. The increase in points from nel_ to nieeA is assumed region.

The

namelist in which

number

of points

The

N is the resulting distribution

the

airfoil,

number

of points

[ 16]. The approach of

aft lower

and

input. It is assumed that the nose region ice accretion occurs. Therefore,

N = niced - n_points

where

in the

in the

nose

using

distribution of N points along computed using equidistribution

a weight a curve from

to ensure to occur

segments

such

that it is an in the iced

is defined

via

that it is the only region

- n_points_aft_upper_region

in the nose region. region

used here is to distribute

PN(U),

is defined

aft lower_region

of points

aft upper

the method

is based

points function

of length

on an equidistribution

on the NURBS based s_e_,

on the

description

surface location

principle of the nose

curvature. of the

For

ith point

a is

'w(s)ds- i-1 o,..w(s)ds where objective

w(s)

is the

weight

is to determine

function the value

and

s is the

of the integrand

14

arc

length

along

si that satisfies

the

curve

the equality

[16].

The

for each

value of where

i. A direct

result

the positive

Therefore,

of using

weight

if the weight

the

function

function

equidistribution

is large,

is based

on surface

regions

of higher

curvature

leading

to a better

problem

at hand,

the weight

function

is known

length

u. Therefore,

using

a change

formulation

the mesh

spacing

curvature,

of variable,

points

representation explicitly

is that

in regions

is correspondingly

will be clustered

of the

in terms

small.

surface.

in

For

the

of the parametric

the equidistribution

relation

arc

becomes

,ow,u,I u It:u) u:iX --"1 _ow(u )

du

2

and (ds/du)

is defined

using

d2=4P;(u). du

where

P:¢ (u) is computed

distributing

int._max

integration

nodes

performing

using

(specified

on

the

a piecewise

eliminates

many

equidistribution

Routines

via

routines.

fit

of

the

GGLib

with

no

iteration

are then used

in

Using the

is evaluated

namelist)

PN(U)

integrand.

associated

In particular,

The integral

DISTRIBUTION

representation

problems

from

GGLib

the

NURBS linear

of the equation.

distribution.

appropriate

equally

parametric the

is required

to evaluate

spaced

space

integral

finite-difference

and

formulation version

to obtain

the resulting

by

(x,y)

of the

the

point

locations

on PN(U).

Using

appropriate

GGLib

routines,

g(u)= I

A clustering

function

the surface

(u)"

is now defined

(u

K(ui)

is the

DISTRIBUTION increase

the

variation

in curvature

The

second

through

curvature

namelist strength

of the

peaks

and increase

step in formulating

repeated

and

variable

application

is computed

(u)(u)" (u (P;,(u)"P;,(u))

at each of the integration c(uj)

where

curvature

= K(u_)

tx > 1 is

a clustering

The

of

normalized

the

the weight

(u) l

nodes

O-l/,,)

cluster.

the clustering

using

general

parameter effect

curvature,

i.e.,

is to smooth

to increase

the clustering

of

j = 2,int_

15

by

the

tx is to the

in the point distribution.

function

F(u,)=l(c(u,_,)+2c(u,)+c(u,+,)),

defined

of decreasing

max-

1

function

It is important to note that the geometryis not being smoothed- only the clustering function used to define the weight function in the equidistribution schemeis being smoothed.The purposeof the smoothingis to reducethe variation of the surfacepoint distribution in regions of rapid variation in curvature.Finally, the normalized weight functionis definedin termsof the smoothedclusteringfunctionusing max(_(u),

w(u) =

_min)

_max

where

= maX(Emax/_,Cmin).

Cmin

spacing

to the

specified Points

minimum

Cmin

spacing

in the

via the DISTRIBUTION are distributed

respectively, spacing

a hyperbolic

at the inboard

nose region the trailing namelist.

3.5

nose

namelist

on the aft upper

using

serves region

tangent

surface

the

of

the

tolerance

segments,

function

is set to match

distribution the variable

of Distribution

ratio

maximum 6

which

is

rnax_rnin._ratio.

stretching

end of each segment

the

less than

variable

and aft lower

to ensure a smooth point edge is specified using

Demonstration

to keep

Pu(u)and

contained

the spacing

PL(U)

in GGLib. obtained

The

from

the

in the transition region. The spacing delta_s_te from the DISTRIBUTION

at

Algorithm

It is now appropriate to present results for the point distribution algorithm as well as demonstrate the effects of various parameters that influence the surface distribution. Issues related easily

be

to the fidelity

addressed

by

of the geometric

critical

representation

examination

of several

Ultimately, the issue of surface grid quality numerical calculations and comparing the results addressed in Section 6.

The first case considered GLC305

airfoil

normalized demonstrates

airfoil

of the surface

of unity

is shown

reduce

here is a relatively and is designated

the rapid

varies

at the upper

here.

than

to

points

discrete

smoothing

to rough

distribution surface

rough."

a value

split point.

in the weight

on the surface

variables

smooth

shape

generated

of

or jagged parameter Table

for both smooth

function.

as points

high

This

This

and rough

the

default

surfaces.

result

region and coordinate split point

of smoothing

results

of high curvature

suggests used

of the is to

in a smoother

applying

rather

additional

in ICE_DIST_2D.

is used

when

values

for DISTRIBUTION

Also shown

I6

effect

in regions

surface

for the

a plot of the

of the iced region

ultimately

is the approach

file, dist_rough.ini, 3 contains

the general

are clustered

curvature.

ice shapes.

by LEWICE 5 shows

of zero at the lower

This

can

configurations.

u in the iced The parametric

a portion

surface

only by performing data. These issues are

[17]. Figure

Only

As can be seen from the figure,

variation

distribution

"def

can be addressed with experimental

case 204LEW

from

surface

point

second

representative

weight function versus the parametric coordinate the effe&s of smoothing on the weight function.

on this segment to a value

section

of the iced airfoil

surface

in the figure

is defined

A using

namelist

is the effect

of the

1.2 ......... Unsmoothed --

Smoothed (200 iterations)

0.8

A

0.6

0.4

i.,i: O.2

0

I

0.4

,

I

0.6

0.8 U

Figure variable

5. Effect

max_rain_ratio.

is placed

weight

6 shows

the effect

general

effect

of decreasing

the maximum distribution expense

peak.

of clustering

a fixed

7 shows

204LEW

[17].

a plot of the surface can

be

is the enhancement

number

of points,

seen

net effect

regions.

and equal

spacing

distribution

from

the

region

distribution suggests

the

ice

horn

the

surface

Note,

figure,

the

is implicitly

distribution

interpolates

near

increases these points

smoothed

upper

overall

the right edge dramatically. a smooth

NURBS

curve

17

the

iced

rather

case,

occur

airfoil

of the

cluster=l,

data for case fidelity

airfoil

while the initial the comer

interpolating

the straight-line

of the figure The

wherever

maintaining that

point at the

of the

of higher surface curvature. discontinuities. Note that in

does pass through

while be noted

to

in the figure

geometric

surface

will occur

The

relative

on the surface

In the extreme

it is Ca continuous)

that the curve

It should

using

the

function.

values

shown

and the original

(actually

This condition

however,

approximation.

points

intersects

C 1 continuous

only C o continuity.

NURBS surface

the

is at least

C o continuous. the

where

of 0.2

results.

surface is well maintained and points are clustered in regions However, one point should be made regarding surface slope the

"floor"

weight

of peak

at the other peaks

peak and-other

is unity evet3rwhere

As

is set to 5.0 so that an artificial

of clustering

at the primary

function

Function

cluster on the normalized

the parameter

Given

Weight

function.

of the parameter

is the enhancement

the weight

on Normalized

In this case, the ratio

on the normalized

Figure

Figure

of Smoothing

segments

because

the

approximation than a line segment.

in

the

surface

the original surface point. nature

data is only

In effect, of the

in the original spacing

between

ICE_DIST_2D

1.2 duster = 2.0 ......... duster = 4.0 -- -- cluster= 8.0

0.8

,_ 0.6

0.4

v

i

'

0.2

0

0.4

I

I

0.6

0.8 U

Figure

6. Effect

of Clustering

0.05

Parameter

on Normalized

i

i

Weight

Function

i

Original surface distribution • ICE_DIST_2D surface distn'bution

0.025

>

0

-0.025

-0'0__0.05

Figure

I

I

I

-0.025

0 X

0.025

7. 204LEW

Surface

18

Definition

0.05

i

0.05

i

Odginal surface distribution • ICE_DIST_2D surface distribution

0.025

_-

0

-0.025

i -0.0_5

-0'0-0.05

L 0

[ 0.025

0.05

X

Figure Figure

8 shows

a plot of the surface

case

904EXP

obtained

The

surface

distribution

However, which

from

roughness to cluster.

shows

point

ice shape,

Additionally,

It should

be emphasized

most cases, 3.6

no user intervention

ICE_DIST._2D

The

output

and

informational

output The

that the surface

jagged

challenging.

higher

distinct accretion

for the

curvature.

because

of the

features

about

of ice on the

requires additional points to represent points from the horn region.

distribution

is generated

automatically.

consists

of a file containing

this

For

Output

messages

module

to stdout.

to a file in the PLOT3D, distribution

of

7. This occurs

are fewer

data

is required.

from the ICE_DIST_2D

surface

there

a significant,

lower surface. The lower surface accretion portion of the surface and effectively removes

airfoil more

in regions

as it is in Figure has

iced

case is considerably

clustering

Essentially,

904EXP

Definition

and the original

[17]. This

is not as apparent

of the

Surface

distribution

IRT data

again

the clustering

overall

8. 904EXP

The

three

multizone,

may be viewed

airfoil

formatted, using

segments

are

two-dimensional,

the "display

distribution"

the surface concatenated grid

format

directive

data and [9]. from

ICEG2D. The case_name.dst.

output file name is associated with dist_file with the default being A sample of the information printed to stdout where case_name has been

set to "623exp"

and surface_type

Generating Iced

geometry

has been

distribution

using:

file

Clean geometry file Parameter definition

set to "rough"

file

623exp.dat

- 623exp.cln - dist_rough.ini

19

is shown

below:

Distribution

Begin

output

surface

distribution

=

61

n_points_nose_region n_points_aft_upper_region

= =

251 I01

lower_surface_split_point

=

0.400000

= = =

0.100000 0.005000 2.000000

rpower max_min_ratio

= =

8.000000 5.000000

int_max n_smooth

= =

4000 800

WARNING

***

Open

location

set

at

WARNING

***

Open

location

set

at

Ratio

=

Number

Lower

points

edge point

Surface

length)

lower

clean

airfoil.

edge

found

for

of

upper

and

lower

points.

airfoil

points. iced

airfoil.

=

621

5.373643

-

ds(gen)

=

0.005098,

ds(spec)

=

0.005000

- ds(gen)

=

0.003072,

ds(spec)

=

0.003003

- ds(gen) - ds(gen)

= =

0.003039, 0.005049,

ds(spec) ds(spec)

=

0.003003

=

0.005000

distribution

consists

generation

of an inventory

DISTRIBUTION. action

of points

for

and

surface

Split point Trailing edge

and

found

upper

surface

Split

the namelist

edge of

trailing average

on =

Trailing

Upper

trailing average

1.052840 of

ds(max)/ds(min)

approximate

1.000000 3

upper_surface_split_point delta_s_te cluster

***

number

calculation.

n_points_aft_lower_region

TE

detected

623exp.dst

= =

***

output

-

prune order

TE

The

file

was

taken.

on the airfoil

maximum

in the nose region

The

of relevant user

The

is then

ratio

surface

to minimum

complete!

file

associations

notified

Siced/Sclea

nieed. Diagnostic

spacing

and a comparison

ratio based

that

an open

is then

n

information

end points of the aft upper segment and aft lower segment. indicating successful completion of the surface definition.

edge

along

follows

was the

showing

an

spacings

a message

of

with

(as opposed

and generated Finally,

by an echo

trailing

output

on cord length

of the specified

2O

followed

to arc at the

is printed

4.

Module ICE_GRID_2D

Automated Even

grid generation

grids

because

for

the

of concave

difficulties

regions

for algebraic

placing

corresponding

obviates

this problem

a marching

scheme

grid layer

by layer

marching

distance

parabolic

[3-7]

algorithms. generate capability The

or elliptic points

file

parameter

effort,

ICE line

is written

allocation.

arguments

for the

grid,

file. These

file names

ICE

ICE_GRID_2D

with

airfoil

the default the input

using

ability

adaptive

a C driver

and

routine

and four

to grid

and

file names

definition the

the Both

grid generation of the

surface

a

file,

block

the

definition

associations

in ICEG2D

for the module

is described

a single-

or double-block,

the directive

"generate

C-

grid."

Input consists

of a file

containing

and a file containing and BLOCK_PARAMETERS. dist_file,

are listed in Tables

Namelist itMax

is required

to define

4-7 below

and are defined

Variable

the

data

data for The airfoil the

initial

in the appropriate

Default

Value

20 2

omega

1.0

addedDissipation

1.0

iWake

40

distWake

15.0 4. Namelist

GRID_PARAMETERS

21

for

the

the surface

surface

for

namelist namelists definition the

grid

to generate an identifying banner in the in the various namelists and their default

nOrder

Table

Typically,

solution

name

file,

generate

is executed

generation algorithm. The case name is used output from the module to stdout. The variables values

using

to automatically

GRID_2D

to ICE_GRID_2D

associated

the

in that

and generates

is specified.

because that

the case

pose

approach

generated.

with

parameter

that follow,

curve

layer,

chosen

passes

can be defined

used

been

in FORTRAN90

generation

One

used for marching

was

regions

the grid. In this context,

data

each

It should be noted in Years 2 and 3.

ICEG2D

In the sections

with the methodology

input

grid

of

have been

to ICE_GRID_2D:

the

have

challenging

of the difficulty

grid.

to generate

challenge.

are

These

because

of the

thickness

scheme

airfoils

airfoil.

as the initial

of layers

the

of the

algorithms

technique

number i.e.,

iced

boundary

distribution

a parabolic

memory

GRID_PARAMETERS NUMBER_OF_BLOCKS file,

outer

[ 18] schemes

GRID_2D

type grid. The module

The

the

a specified

distribution,

or by user specification.

4.1

on the surface

is to use a marching

until

is an, as yet, unsolved

single-element

grid generation

on

uses the surface

In this

as command

along

occurring

and hyperbolic

dynamic

output

configurations

simple

solution adaptive grids [4,5]. is scheduled for implementation

module

utilizes

for complex

topologically

Variables

sections.

Namelist nBlocks

Variable

single I Table

Table

5. Namelist

block.ini

double_block.in| 2

NUMBER_OF_BLOCKS

Variables

Namelist Variable distFirstPointLE_ nl

single_block.ini 1.0xl0 "_

distFirstPointTE_ nl

1.0x 10 .6

distFirstPointDSB_nl

1.0xl0

distOuterBoundary_nl

15.0

xTransLower_nl

0.5

xTransUpper_nl

0.5

jMax_nl

101

6. Namelist

BLOCK_PARAMETERS

"_

Variables

- Single-Block

Namelist Variable distFirstPointLE_nl

Block

#I

Block

1.0xl0

"_

Computed

distFirstPointTE_ nl

1.0x 10 .5

Computed

distFirstPointDSB_nl

1.0x 10 .5

distOuterBoundary_nl

1.0

Computed 14.0

xTransLower_nl

0.5

NA

xTransUpper_n/

0.5

NA

jMax_nl

71

21

Table

4.2

7. Namelist

Blocking

The ICEG2D

framework

topology

using

the techniques

requires

allows

between j=constant work.

for two different

and a double-block

number

outlined one,

by taking

- Double-Block

block.

The

j=jMax-2

in the

inner

structured

The

The inner

in the

of an initial

the coordinates

on the surface surface

topology.

below.

is treated

the specification

last two cells of the inner generated

Variables

#2

Grid

Strategies

block

as block

BLOCK_PAR,,MMETERS

Grid

same

surface. outer-block

single-block

block

on the inner is forced

22

The

outer

initial grid.

outer

block surface

last points Recall

to be odd,

a single-

grid is generated

of the double-block

manner. The

of the first and

grid

grid configurations:

block

designated

grid

generation

is assumed is defined and every

that the number so this

directly

grid,

approach

to overlap using other

the

a surface point

of points

in

on a

will always

In general,the file single

occurrence

block_parm_file

of the BLOCK_PARAMETERS 4.3

Wake

Because cases.

Therefore,

the

points

namelist

point

Therefore,

of (nBIocks+l)

different

namelists

plus the nBIocks

- one for each block

at the airfoil

it is necessary

to the downstream

to define boundary

to the x-axis.

the cut is given

so that

a wake

-

a

occurrences

in topology.

edge,

a C-type

cut that extends

The distance

of points

the

variable

from

downstream

the trailing

edge

is given

edge of

is specified

The

point

in all

it is assumed

boundary

of the trailing

surface

is used

Here,

distWake.

that the trailing

of points on the j=l

grid

domain.

to the downstream

using

by iWake. Note

the number

the total number

trailing

of the computational

GRID_PARAMETERS

defining

wake

namelists

resolution

that the cut is parallel via

consist

NUMBER_OF_BLOCKS

Cut Definition

of improved

the airfoil

will

of the namelist

number

of

is considered

edge

a

is iWake-1.

by

iMax = nic,a + 2 x (iWake - 1)

The

distribution

function

of points

on the cut

[19]. The first point

to the distance

from the trailing

airfoil

This distance,

surface.

of points function. 4.4 The

normal

function

downstream

Distance

distance

defined

using

the distance

As implemented locations:

the distribution

is generated

functions

considered.

here,

distance

the leading

the edge

and

distFirstPointDSB_nl.

Using

xTransUpper_nl, point

linear

on the initial

data

a distance

of the trailing boundary, using

stretching equal

edge

on the

and the number

the hyperbolic

tangent

Distribution

distribution

distFirstPointTE_nl,

tangent

is located

to the downstream

to compute

in [19]. The distance

stretching

edge

upstream

using

to the first point

the distance to the last point and the total number function was selected because it was shown to induce several

a hyperbolic

of the trailing

edge to the first point

on the cut are sufficient

Normal

is defined

to the

of the airfoil the

interpolation

point

boundary

values

hyperbolic

off the wall is specified

off the of

is used to define

the

23

the distance

and lower

wall

surfaces

stretching along

hyperbolic truncation

is specified

the trailing

and the transition

For the upper

tangent

of points. The the least overall

distFirstPointLE_nl,

downstream

these three

surface.

first

the

edge

at three

of the airfoil

computational points

with

tangent error of

domain

xTransLower_nl

to the first point

and

for each

_)LE

5:=

,

_ + f. _. - x're_s-U'L t, XrE - xTx_s_u,L

18 re __) _ )

xt,e>g22,

the

the 11 derivatives.

lines can lead to mesh smoothing

term

term

In nonconvex

regions,

line crossing.

The approach

(1 + v) in the Poisson

smoothing

equation

is the

lack of smoothing taken

equation

term along

here is to include

the

where

xf(O_)

v=,/max(gll'gaa) V

Poisson

the resulting

g22

where 1

0

streams

to run these

to generate

assume

file newdata.cln.

types

directive

needed

$ICEG2D_DlR/examples.

is one in which

$ICEG2D_DIR/examples/example_1. experimental

ICEG2D

and the

batch 904iced

double

input.npc

gen input gen restart # gen solution exit

49

note

that the minimal

The restart

file is named

etc. in batch mode with and a clean airfoil driver

file driver.inp The NPARC

DISTR/BUTION

a double-block The

Also,

of "define."

directive

grid stream

an experimental defined in the are located information

namelist using contained

in

the default

ice file

in the file is the

file

double-

in driver.inp

is

The ICEG2D

scriptisexecuted using "ICEG2D




output."

In this

case,the input fileis named 904ieed.inp,etc.If user-definedblocking parameters are to be used and are defined in the localfilebloek_def.inp, the directive"def block_parrn double" should be replaced with "def block_parm solution"directivehas been commented out.

block_def.inp".Note that the "gen

We now consider a case starting from an intermediate step. Here, we assume a singleblock grid file exists that is in the PLOT3D unformatted, two-dimensional, multizone, grid

format

[9]

and

is named

grid.xyz.

The

NPARC

information

file

is located

in

prob.inp. Both files are located in the directory $ICEG2D_DIR/examples/example_3. The directive stream for an interactive session is listed below: ICEG2D>

def

case

problem!

ICEG2D> ICEG2D> !CEG2D>

def def show

grid nparc

grid.xyz prob.inp

ICEG2D> ICEG2D>

gen gen

input restart

iCEG2D> ICEG2D>

gen exit

solution

Although the ICE_GRID_2D

file associations required are not needed, we still need

for the NPARC

input

current defined

file, the restart

file associations as intended.

Finally,

a directive

automatically

generate

that the "show"

for checking

is included

grids for an icing

in $ICEG2D_DlR/examples/example_4. geometries 6221ew.dat,

file, etc. Note

and is useful

stream

by the modules ICE_DIST_2D and a case name for the default file associations to make

to i11ustrate calculation. The

data

how

sure

is given

could

a sequence

for

def

mode

auto-gridding

for

Use

NLF0441

to batch

batch

smooth

surface

parameters

for

each

# # Clean airfoil # def surface smooth def case nlf0441 def iced_geom nlf0441.cln gen dist # # Use

the

default

single

block

topology

#

50

been

used

to

case

airfoil

through 6211ew.dat, to simulate automatic

# #

be

of iced

by:

# # Set mode #

has

The files for this case are contained represent

# # Script

lists all the

everything

ICEG2D

starting from the clean airfoil nlf0441.eIn, proceeding and concluding with 6231ew.dat. The directive stream

regridding

directive

(the

default)

def gen #

block_parm grid

# Case

single

6211ew

# def def

surface smooth case 6211ew

def gen #

clean_geom dist

nlf0441.cln

def gen #

block__Darm grid

single

#

Case

6221ew

# def def

surface smooth case 6221ew

def

clean_geom

gen #

dist

def gen #

block_parm grid

# Case #

nlf0441.cln

single

6231ew

def

surface

def

case

6231ew

smooth

def gen #

clean dist

geom

def gen #

block_parm grid

nlf044i.cln

single

exit

Notice

that after

This is because this

been

an

each new "def case" it is automatically

actual

regridding

directive,

redefined

by the "def

calculation,

LEWICE as well as the LEWICE input shows the sequence of grids automatically growth.

the clean calls

airfoil case"

to the

ice

file must be respecified. directive. growth

Of course, prediction

modules would need to be included. Figure generated using ICEG2D for the simulated

51

had code 30 ice

NLF0441

Clean

Airfoil

621LEW

622LEW Figure

30. Automatic

623LEW Regridding

52

for Simulated

Ice Growth

8. An

Summary integrated

geometry/grid/simulation

automate

computational

with

accretion.

ice

functions:

1)

fluid

dynamics

ICEG2D

generate

a

was

mode

using

purpose

a script

CFD

package,

(CFD)

simulations

designed

grid-ready,

characteristics of the iced airfoil generated surface point distribution, run the general

software to

ICEG2D,

automatically

surface

was

definition

perform based

the

solver

NPARC.

ICEG2D mode

primary

geometrical

grid files

can be operated

by entering

using the needed to

in either

directives

from

a batch

a command

line from within a Unix shell. ICEG2D consists of four modules that are integrated framework of associations that relate external data to internal file names. ICEG2D

has

geometry

module

surface

of

geometry airfoil was

the

shapes

skewness.

tested

by

of ICEG2D iced

module

validated

geometric

been

application

airfoil

while

has the ability

and to prune based

characteristics The second

on

to numerous

was validated

of condition grids.

the

The

criteria,

is based

iced

cell

area

on the accuracy

The first condition

automatically

generated

of the grids demonstrated

for problems with significant regions and is the subject of further research.

53

fidelity.

of

condition,

of solutions

was satisfied. flow

on the

Additionally,

descriptions

positivity

The

points

and

clean

module

is

based

no

excessive

computed

At this time, separation

the

with

The grid generation

a necessary

with a

configurations.

to distribute

airfoil

and twists.

first, i.e.,

airfoil

geometric

incomplete

with loops

criteria.

iced

on its ability

maintaining

to merge

ice shapes two

based

to

airfoils

three

on

surface, 2) generate a high-quality and 3) generate the input and restart

file or in an interactive

developed

for single-element

has

using

on the

the validity not

been

9.

References

1.

NPARC

User's

2.

G.B.

3.

Report, Mississippi State University, May 1999. S. Nakamura, "Noniterative Grid Generation Using

Hong,

Parabolic 5.

6.

R.W.

Inc., New

Noack,

Differential

Dimensions",

Dynamics

and Related

Thompson,

Elsevier

D.S. Thompson Semistructured

Fields,

Roundtable,

171-178,

J.K.

9.

FAST

Chung,

private

User Guide.

10. W. B. Wright, 0249,

Adaptive

J. Hauser,

Aircraft

Y. Choo,

New

J. Slater,

for Beta Version Dimensional NASA

August

Under

Results

Meeting,

System

Grid Generation,

Springer,

16. J. F. Thompson, Elsevier Science

Paper

NV, January

Generation

and J. Chung, for Interactive

Conf.

Num.

20. B. K. Soni, Math.

Methods

Comp.,

App. Math.

May,

59, 151-164

"User

Manual

Two-

and Refinement,"

2 nd Ed., Monographs

in Visual

1999.

Comp.,

Meshes

Fluid Dyn., Mesh

99-0375,

1997.

communication,

"Computational

"Elliptic

Study of

Modification,

Z. U. A. Warsi, and C. W. Mastin, Numerical.Grid Publishing Company, Inc., New York, 1985.

Scheme",

1999.

1988 Book,

51,181-205 for Boundary

Generation,

Lecture

Generation

Notes

Systems:

(1993).

55

Grid

(1992). Layer

in Physics, Control

Problems,"

Proc.

8, 171-177

(1971).

Functions

99-

1999.

17. J. K. Chung, private communication, June 1999. 18. W. M. Chan and J. L. Steger, "Enhancements of a Three-Dimensional 19. G. O. Roberts,

Paper

Ice Accretions,"

"Numerical

AIAA

Reno,

D. Braun,

The NURBS

private

Meeting,

1999.

NV, January

Airfoil

and J. Slater,

C. Bidwell,

and W. Tiller,

Presented

2.0," AIAA

Reno,

"Modern

-- A Software

Oct.,

Communication,

June,

for LEWICE

Icing Conditions,"

Sciences

T. Henderson,

Boundary/Field

15. J. K. Chung,

in Three

1999.

Sciences

Certain

of Turbo-GRD

and J. F.

1991.

Grid Generation

M. Potapczuk,

TM- 1998-206631,

14. L. Piegl

P. R. Eiseman,

York,

in Two

Fluid

Scheme," AIAA Paper 2000-1004, Reno, NV, January 2000.

of Validation

at the 37 th Aerospace

13. Y. Choo,

Grid Generation

1999.

Marching Meeting,

A. Reehorst,

Controllability

Presented

(1990).

of Quad- and Hex-Dominant, Layer Scheme," Proc. 8 th International

"Semistructured

at the 37 th Aerospace

Using

in Computational

11. H. E. Addy, M. G. Potapczuk, and D. W. Sheldon, NASA TM 107423, March 1997. 12. J. Chung,

Science

,

"A Summary

Presented

Parabolic

Company,

October

communication,

Differential

J., 28, 1016-1023

Eds. A. S.-Arcilla,

and B. K. Soni,

Partial Elsevier

Grid Generation

Grid Generation

Publishing

Dimensions using a Parabolic at the 38 th Aerospace Sciences 8.

AIAA

and B. K. Soni, "Generation Meshes using an Advancing

Thompson

Technical

1982.

"Solution

Numerical

ERC

Parabolic

"Solution-Adaptive

Equations",

Science

Library,"

Ed. J. F. Thompson,

York,

and I. H. Parpia,

and Three

D.S.

& Grid Generation

and D. A. Anderson,

Partial

Meshing 7.

1996.

Grid Generation,

Company,

Noack,

3.0,

A Geometry

Numerical

Publishing R.W.

Version

"GGLib:

Equations", 4.

Guide

Revisited,"

Int. App.

21. P. R. SpalartandS.R. Allmaras,"A Aerodynamic Meeting, 22. K.-Y.

Flows,"

Reno,

Chien,

AIAA

Paper

NV, January

1992.

"Predictions

Reynolds-Number

One-Equation Turbulence Model for 92-0439, Presented at the 30 th Aerospace

of Channel

Turbulence

Model,

and Boundary-Layer AIAA

56

J., 20, 33-38

Flows (1982)

with a Low-

Sciences

REPORT Public

reporting

gathering collection Davis

burden

for

and maintaining of information,

Highway,

Suite

this

collection

the data including 1204.

DOCUMENTATION of

information

is estimated

needed, and completing suggestions for reducing

Arlington,

VA

22202-4302,

and this

and

t. AGENCY USE ONLY (Leave blank)

PAGE

to average

1 hour

per

reviewing the collection burden, to Washington

to the

Office

of

response,

including

the

of information. Send Headquarters Services,

Management

and

Budget,

2. REPORT DATE February

FormApproved OMBNO.0704-0188 time

comments Directorate

Paperwork

for

reviewing

Fields

searching

existing

data

sources,

ReduCtion

Project

(0704-0188),

Washington.

DC

20503.

3. REPORT TYPE AND DATES COVERED 2000

Final

4. TITLE AND SUBTITLE ICEG2D--An

instruCtions,

regarding this burden estimate or any other aspect of this for Information Operations and Reports, 1215 Jefferson

Contractor

Report

5. FUNDING NUMBERS

Integrated

Software

for Single-Element

Package

Airfoils

With

for Automated

Prediction

of Flow

Ice Accretion WU-548-20--23--00 NAG3-2235

6. AUTHOR(S) David

S. Thompson

and Bharat

K. Soni

PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) Mississippi State P.O. Box 5325

University

Mississippi

Mississippi

E-12146

State,

9. SPONSORING/MONITORING

39762

Ohio

10. SPONSORING/MONITORING AGENCY REPORT NUMBER

AGENCY NAME(S) AND ADDRESS(ES)

National Aeronautics and Space John H. Glenn Research Center Cleveland,

8. PERFORMING ORGANIZATION REPORT NUMBER

Administration at Lewis Field

NASA

CR--2000-209914

44135-3191

11. SUPPLEMENTARY NOTES Project

Manager,

organization

Yung

code

K. Choo,

5840,

Turbomachinery

and Propulsion

Systems

Division,

12a. DISTRIBUTION/AVAILABIMTYSTATEMENT Unclassified Subject

NASA

Glenn

Research

Center,

(216)433-5868.

12b. DISTRIBUTION CODE

- Unlimited

Category:

This publication

02

Distribution:

is available from the NASA Center for AeroSpace

Nonstandard

Information,

(301) 621-0390.

13. ABSTRACT (Maximum 200 words) An integrated

software

for single-element generating

package,

airfoils

a grid-ready,

surface

ing a high-quality

grid

to run the general

purpose

interactive

mode

of a three-year with

with

using

ice accretion.

definition

solver

directives

Specifically,

developed

ICEG2D based surface

of the operation discussed.

point

a command

can

and

in batch

package.

summarizes

related

to CFD

employed Validation

dynamics three

of the iced

(3) generating

report

issues

the technology

of the software

fluid perform

characteristics

be executed

line. This

to address

describes

computational

to automatically

distribution,

ICEG2D

program

this document

to automate is designed

on the geometrical

NPARC. from

and development

procedure, and a description modules of ICEG2D is also

was

the generated

CFL)

by entering research

ICEG2D, ice accretion.

mode

airfoil and

using

a script

activities

in the software, of the geometry

simulations functions:

surface,

the input

simulations

14. SUBJECT TERMS

(CFD) primary

(I)

(2) generat-

restart

files

needed

file or in an

completed

in the first year

for aircraft

components

the installation and

grid

generation

15. NUMBER OF PAGES

65 Aircraft ice; Grid generation; Aerodynamics

16. PRICE CODE

A04 17. SECURITY CLASSIFICATION OF REPORT

Unclassified NSN 7540-01-280-5500

18. SECURITY CLASSIFICATION OF THIS PAGE

Unclassified

19. SECURITYCLASSIFICATION OF ABSTRACT

20. LIMITATION OF ABSTRACT

Unclassified Standard Form 298 (Rev. 2-89) Prescribed by ANSI Stcl.Z39-1B 298-102