Artyukhov А Е
Computer simulation of vortex flow hydrodynamics
ISSN 1335-7972 (Print) ISSN 1339-2972 (On-line)
Computer Simulation of Vortex Flow Hydrodynamics Artem Artyukhov 1
Candidate of Technical Sciences, Associate Professor, Sumy State University (SSU), Senior Lecturer of Processes and Equipment of Chemical and Petroleum-Refineries Department, Sumy, Ukraine , Email:
[email protected]
Keywords Vortex granulator, Hydrodynamics, Simulation, Velocity
Article
Abstract Solution of the equations of gas flow dynamics and granule motion together with the application software package enabled calc ulations of velocity field in a vortex granulator working volume. The analysis and comparison of theoretical calculation results, computer simulation and experimental research were performed. The proposed complex approach allows forecasting of the character of granule motion in a vortex granulator on a stage of equipment designing and selection of the optimal construction of the machine. Research results will be used to develop methods of engineering calculation for vortex machines.
History
Received 07 October 2013 | Revised 25 November 2013 | Accepted 29 November 2013
Category
Original Scientific Paper
Citation
Artyukhov A E (2013) Computer simulation of vortex flow hydrodynamics. Journal of Manufacturing and Industrial Engineering, 12(3-4):25-29, http://dx.doi.org/10.12776/mie.v12i3-4.262
INTRODUCTION Use of vortex flows in mass exchange machines gives an opportunity to intensify a process and to increase specific productivity of technical equipment [1]. In combination with a blanket [2] such machines can be used in granulating processes [3]. A vortex granulator is used mainly in chemical industry and to granulate different substances from solutions and melts and also to create granules with special features (for example, porous ammonium nitrate) [4]. Enterprises, producing granular products, use mainly granulating towers. Heavy expenses for production, technical service and repairing of the granulating towers are caused by their big size and complicated communication system. The prospective way of chemical industry development is to implement new organization of granulation processes using small-sized equipment, which enables reducing of energy consumption, natural resources, labor intensity and provides favorable ecological situation. The vortex granulator produces granular products without granulating towers. Its work is built on granulation from melts, solutions and suspensions, based on improving of the granule flow dynamics to provide: increasing monodispersion of granules, growing in vortex layer; increasing homogeneity of granulometric composition of the finished product. When designing small-sized vortex granulators, special attention is paid to hydrodynamic mode of granule motion in working space of the machine under swirling gas flow. Depending on the constructional peculiarities of the vortex machine, gas flow parameters are selected to keep a granule in the machine working volume for the necessary amount of time. Calculation of granule motion trajectory, based on the hydrodynamic calculation result, enables determination of the optimal configuration of machine working volume. Control and modulation of hydrodynamic characteristics of granule motion process provides an opportunity to get their commercial quality. Solving of this task becomes topical under modern tendencies to use energy efficiency principles in new productions. http://dx.doi.org/10.12776/mie.v12i3-4.262
The aim of the work is to determine hydrodynamic parameters of gas flow and granules motion. The object of the research is a vortex granulator with variable sectional area of working space. The subject of the research is hydrodynamic conditions of flow motions in the vortex granulator.
MATERIAL
AND METHODS, THEORETICAL MODELING, COMPUTER SIMULATION AND EXPERIMENTAL STUDY Program implementation of the theoretical model was carried out by using Delfi programming language (www.delphisources.ru). COSMOSFloWorks (www.solidworks.com) and Flow Vision (www.flowvision.ru) complexes were used in this work for computer simulation of flows hydrodynamics and visualization of research results. Experimental research of hydrodynamic conditions to form vortex blanket was conducted on the model sample of the vortex granulator [5]. The work of "Vortex Flow" program bases on the Navier– Stokes equations (1) and gas flow continuity (2) (for gas flow) [6] and a system of differential equations of granule motion (3) [7]
2
V 2V 2V 1 V V Vr V 1 p r r r r Vr Vz r E 2 2 dr z gs r r r r r z r2
2V 2V V V VrV 1 V V Vr Vz E , r 2 dr z r z 2 r r r 2 2V 1 V V Vz V 1 p z z Vr Vz z E 2 r r dr z gs z r r2
,
(1)
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Artyukhov А Е
Computer Simulation of Vortex Flow Hydrodynamics
Vr Vz V r 0. r z r 2
m
d r d
2
2
m
d d
2
2
m
d z d
2
(2)
r 8m gs d gr WrW V W , r 8m gs d gr g Vz Wz , 8m 2
W
gs d gr
p – pressure of the gas stream; E – coefficient of turbulent viscosity; m – mass of granules, – the time; W ,W ,W – r
Vr Wr ,
z
(3)
where dr, d, dz – basic movement gains for the respective axes; V ,V ,V – radial, circumferential and r
j
the gas, respectively; r – the current radius of the working space of the vortex granulator; – density of the gas stream; gs
radial, circumferential and longitudinal/perpendicular components of the velocity of the granules, respectively; g – acceleration of gravity; ψ – linear coefficient of the granule’s resistance to the gas flow; – viscosity of the gas stream; gs
d gr
– diameter of the granule.
A user enters data for calculation in respective margins of a dialog box. When entering initial data, a user selects an interval of vertical and horizontal splitting of working space in a vortex machine. The program displays calculation data (prints if necessary) as a list of results and characteristic curve (fig.1).
z
longitudinal (or perpendicular) components of the velocity of
Figure 1 Visualization of the calculation results in "Vortex Flow" program: a - for gas flow; b - for a granule.
A series of additional researches was conducted to determine an influence of working space configuration and way of gas flow swirling on a character of gas flow motion. The series includes computer simulation of flow motion hydrodynamics. Results of computer simulation are compared with data of
theoretical calculation and previous experimental researches [8]. Calculation model bases on the finite volumetric method of solution of hydrodynamic equations and use of a square adaptive mesh with local refinement. Results of computer simulation for some cases are presented on figures 2 and 3 [9].
Figure 2 Influence of the way of gas flow swirling (number of perforated vortex blades n=6, blades angle α=30º) on the character of distribution of continuous phase radial velocity for various configurations of vortex machine working space.
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http://dx.doi.org/10.12776/mie.v12i3-4.262
Artyukhov А Е
Computer simulation of vortex flow hydrodynamics
a
b
c
d
Figure 3 Influence of the vortex constructional characteristics on the character of distribution of continuous phase radial velocity in a vortex machine working space: a - number of perforated vortex blades n=3, blades angle α=30º; b – n=5, α=30º; c – n=6, α=30º; d – n=8, α=30º; e – n=3, α=60º; f – n=5, α=60º; g – n=6, α=60º; h – n=8, α=60º.
Research of the process of granule vortex blanket formation enabled to determine the main stages of formation of twophase flow spiral motion. Meanwhile we determine typical areas of two-phase flow distribution in the vortex working space with
forecasting of areas with granular motion extra intensity and stagnant zones. Development of the vortex blanket was studied stepwise from the beginning of its formation to its operation mode (figure 4).
Figure 4 Formation of granule vortex blanket
RESULTS AND DISCUSSION Analysis of the research results enabled determination of the influence pattern of the vortex granulator construction on velocity distribution of gas flow motion. The vortex configuration: - when increasing the blade angle, gas flow peripheral velocity on the working space section reduces; - when increasing the blade angle, chaotic gas flow swirling in a gas distributor appears;
http://dx.doi.org/10.12776/mie.v12i3-4.262
- when the number of blades grows, uneven distribution of velocity appears − gas flow velocity in input is much higher than in output of the machine; - when increasing the blade angle, large stagnant zones of granules appear. Configuration of the working space: - when increasing the cone expansion angle, large stagnant zones appear in the center; - under configuration of the working space in a form of cylinder, uneven distribution of gas flow velocity is observed − velocity in input is much higher than in output of the machine, and the center contains zones of lower velocity; - under configuration of the working space in a form of confuser, gas flow velocity grows while moving through the working space of the machine. 27
Artyukhov А Е
Computer Simulation of Vortex Flow Hydrodynamics
Different character of the distribution of gas flow velocity in the working space of the vortex granulator provides an opportunity to get granules from materials with various properties (strength, thermal stability, porosity etc.). Comparing simulation results with experimental data [8] (figures 5 and 6) makes possible to estimate characteristic areas of granule motion in the working space of various configuration. Figure 5 Characteristic areas of granule motion in the vortex machine with a "cylinder-diffuser" working space: 1 - area of vortex flow formation; 2 - central area with a blanket of a fountain type; 3 - area of combined blanket; 4 - area of vortex granule motion; 5 - area of lower intensity of granule motion
Figure 6 Characteristic areas of granule motion in the vortex machine with a "diffuser-confuser" working space: 1 - zone of lower granule motion velocity; 2 - zone of fountain granule motion; 3 - zone of vortex granule motion.
CONCLUSION AND FUTURE DIRECTION OF RESEARCH Thus, obtained results of the research of vortex flow hydrodynamics enable selection of the optimal configuration of working space and construction of the vortex for vortex machine. In addition, the necessary quality of the finished products depending on the requirements to thermal processing and strength is ensured.
a
b
Constructions of the vortex granulators, designed on the basis of hydrodynamic calculations, [10-12] (figure 7) allow to obtain: granules of the given structure with their size classification; granules of porous structure with strength retention (without destruction of inner crystal structure).
c
d
Figure 7 Constructions of vortex granulators: a - with melt spraying; b - with previous moistening of granules and simple inner case; c - with previous moistening of granules and compound inner case; d - with separation section.
Main advantages of the vortex granulators: possibility of essential reduce of sizes (height in particular) of the working space; increase in time of keeping a granule in a working space of the granulator; possibility to control granule motion in the granulator working space; possibility to create intensive turbulence in the granulator working volume;
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universality (possibility to conduct granulation and drying processes in the volume of the same machine); workability and simple producing; possibility of quick resetting up and change of constructional and technological parameters if necessary. Further research aims at study of the efficiency of heat and mass exchange processes in vortex granulator within their various constructions. Methods of engineering calculation of such equipment will be developed on the base of the obtained results. http://dx.doi.org/10.12776/mie.v12i3-4.262
Computer Simulation of Vortex Flow Hydrodynamics
Artyukhov А Е
REFERENCES [1] Kocherhin M O, (2010) Hydro and thermodynamic conditions for porous structure of ammonium nitrate formation, PhD dissertation, Chemical Technology Processes and Equipment, Sumy State University, Sumy, Ukraine. [2] Dvoretskiy S I, Korolev V N, Nagornov S A, (2006) Technique and technologies of fluidization: the heat treatment and vulcanisation processes, Mashinostroenie, Moskow, Russia. [3] Аrtyukhov A E, Demchenko A N, (2013) Refinement of porous ammonium nitrate obtaining methods in vortical devices, Acta Universitatis Pontica Euxinus, 2: 10-12. [4] Аrtyukhov А E, Sklabinskyi V I, (2012) Production of granules with special properties in small-sized vortex devices, Modern scientific research and their practical application, J31207: 138-147. [5] Zheba K V, Sklabinskyi V I, Аrtyukhov А E, (2008) Hydrodynamics of two-phase vortex flows. Effect on the size of the granulation equipment», Chemical Industry of Ukraine, 4: 47-52. [6] Sklabinskyi V I, Аrtyukhov А E, (2008) Calculation of involute streams hydrodynamic parameters in vortical type granulators by analytical method», Bulletin of Sumy State University, 3: 62-70. [7] Sklabinskyi V I, Аrtyukhov А E, (2010) Determination of hydrodynamic characteristics of the dispersed phase in the small vortex devices», Bulletin of Kremenchuk Mykhaylo Ostrogradskiy State Polytechnic University, 6(59):196-201. [8] Аrtyukhov А E, Marenok V M, Sklabinskyi V I, (2008) A comprehensive study of vortex fluidized bed and the conditions of its use in fertilizer production technology, Bulletin of Sumy National Agrarian University, 3(19):182-185. [9] Аrtyukhov А E, Demchenko A N, (2012) Modeling of hydrodynamic conditions of disperse phase balance in small-sized vortex machines to produce granules with specific properties, Proceedings of the 3th International Conference Computer modeling in chemistry, technology and systems for sustainable development», Kiev, Ukraine. [10] Artyukhov A E, Sklabinskyi V I, Zheba KV, (2010) patent no. 90798, Method and device for porous structure granules getting, Ukraine. [11] Artyukhov A E, Sklabinskyi V I, (2012) patent no. 99023, Method and device for porous structure granules getting, Ukraine. [12] Artyukhov A E, Liaposhchenko O O, Sklabinskyi V I, (2010) Inertial filter separators to clean end gases in vortex granulators, Acta Universitatis Pontica Euxinus, 1:67-69.
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