Computational grid impact on numerical computing results of three-dimensional non-stationary swirl flow behind the vane swirler

DOI: 10.34759/vst-2020-1-122-132

Аuthors

Aleksandrov Y. B.^*, Nguyen T. D.^**, Mingazov B. G.^***, Sulaiman A. I.^****

Kazan National Research Technical University named after A.N. Tupolev, 10, Karl Marks str., Kazan, 420111, Russia

*e-mail: Alexwischen@rambler.ru
**e-mail: nguyenthedat1609@gmail.com
***e-mail: BGMingazov@kai.ru
****e-mail: Armin.wrya@mail.ru

Abstract

The balanced design of the front-mounted device ensures combustion chamber efficiency and gas turbine engine at large. In the majority of modern gas turbine engines for ground and aviation purposes, a vane swirler is being installed concentrically with the fuel nozzle at the flame tube inlet. The swirler forms a swirl of air, and facilitates the best mixing conditions for air-fuel mixture. Besides, while the flow swirls in a low-pressure zone, its core is formed, which allows return gases fr om the flow periphery to the core of the swirled jet, forming thereby a reverse flow zone, and stabilize the fuel combustion by the stall characteristics. Increasing the swirler blades installation angle leads to intensification of the air- fuel mixture mixing, and a reverse flow zone boundaries expansion. However, hydraulic losses at the front-end device are increasing herewith, which, in its turn, contributes to the engine power or thrust reduction.

The fuel-air mixture mixing quality characterizes the efficiency of the front-end device. The majority of works by Lefebvre A., Kosterin V.A., Gupta A., Akhmedov R.B., and others suggest evaluating mixing process by the mixing coefficient, which represents the ejected air consumption to the swirled jet consumption ratio:

where m is mixing coefficient; G_e is the flow rate of the ejected air; G_sw is the flow rate of the swirling jet.

In our work, an experimental setup was developed to study the swirler mixing coefficient. Using the FMD (Fused Deposition Modeling) method of printing, various designs of the swirl with different blade swirler installation angles were created, which were blown into the open space. The flow visualization was realized by smoke pollution of the air supplied to the swirler. In the course of the experiment, both temperature and total pressure fields of the flow were measured in axial and radial directions. Temperature distributions were employed for mixing coefficient (m) computing. Bases on these measurements the coefficient was computed by the expression:

where T_sw, T₀ , T_y are the temperatures in front of the swirl, in the jet and in the ambient air respectively.

A spatial computational domain, simulating the volume of the combustion chamber flame tube, was developed for numerical studies of the vane swirler. It is well known that computational grid strongly affects computation results. It is characterized by the type and number of elements; characteristic size, and the presence of near-wall thickening. The grids of three basic elements types, such as tetrahedral, hexahedral, and polyhedral, were employed. The polyhedral grids were obtained the tetrahedral grid converting. The number of elements herewith decreased by six times, and the number of nodes increased about five times, which allows compute gradients of parameters variation more accurately compared to tetrahedral due to the fact that one finite element has more nodal points. However, such a transformation does not allow precisely control the characteristic size of the elements, and a deterioration of the result due to the increase in the characteristic size of the grid element can occur.

A combined DES turbulence model (Detached Eddy Simulation) in a non-stationary setting was used for computing. The calculation was performed in the ANSYS Fluent 19.2 software with an academic license.

The performed experimental studies of flow mixing behind the scapular swirler were compared with numerical calculations using various grid models. The best results in numerical simulations were obtained when using the DES viscosity model in an non­stationary set of calculations, and hexahedral mesh elements. The polyhedral mesh obtained by converting from tetrahedral elements did not demonstrate good results, as the original tetrahedral mesh had. An increase in characteristic size of the elements led to a greater deviation of the calculated data from the experimental ones. The results obtained are valid for swirlers with various blade angles.

Keywords:

GTE combustion chamber, numerical simulation, flow swirl, mixing coefficient, grid element size, computational grid type

References

1. Mingazov B.G. Kamery sgoraniya gazoturbinnykh dvigatelei. Konstruktsiya, modelirovanie protsessov i raschet (Combustion chambers of gas turbine engines. Design, processes modeling and calculation), Kazan, Kazanskii gosudarstvennyi tekhnicheskii universitet, 2006, 220 p.

2. Kutateladze S.S., Volchkov E.P., Terekhov V.I. Aerodinamika i teplomassobmen v ogranichennykh vikhrevykh potokakh (Aerodynamics and heat and mass exchange in limited vortex flows), Novosibirsk, Institut teplofiziki SO AN SSSR, 1987, 282 p.

3. Gupta A.K., Lilley D.G., Syred N. Swirl flows. Abacus Press, Tunbridge Wells, England, 1984, 475 p.

4. Akhmelova R.B., Balagula T.B., Rashidov F.K., Sakaev A.Yu. Aerodinamika zakruchennoi strui (Swirling jet aerodynamics), Moscow, Energiya, 1977, 240 p.

5. Garbaruk A.V., Strelets M.Kh., Shur M.L. Modelirovanie turbulentnosti v raschetakh slozhnykh techenii (Turbulence simulation in complex flows calculations), St. Petersburg, Politekhnicheskii universitet, 2012, 88 p.

6. Nguen T.D., Aleksandrov Yu.B., Mingazov B.G., Sulaiman A.I. Materialy Vserossiiskoi nauchno- tekhnicheskoi konferentsii molodykh uchenykh i spetsialistov (28-30 May 2019) “Aviatsionnye dvigateli i silovye ustanovki”, Moscow, TsIAM im. P.I. Baranova, 2019, pp. 130-131.

7. Nguen T.D., Aleksandrov Yu.B., Mingazov B.G. Materialy VII Vserossiiskoi konferetsii s mezhdunarodnym uchastiem (16-18 October 2019, Rybinsk) “Teplomassoobmen i gidrodinamika v zakruchennykh potokakh”, Yaroslavl, Tsifrovaya tipografiya, 2019, p. 56.

8. Chaouat B. The State of the Art of Hybrid RANS/LES Modeling for the Simulation of Turbulent Flows. Flow, Turbulence and Combustion, 2017, vol. 99, no. 2, pp. 279-327. DOI: 10.1007/s10494-017-9828-8

9. Chenoweth J.D., Kannepalli C., Arunajatesan S., Hosangadi A. Modeling Swirling Jet Flows Using a Hybrid RANS/LES Methodology. 44th AIAA/ASME/ SAE/ASEE Joint Propulsion Conference & Exhibit (Hartford, CT, 21-23 July 2008). DOI: 10.2514/6.2008-4746

10. Dekterev A.A. Materialy VI Vserossiiskoi konferentsii s mezhdunarodnym uchastiem (21-23 November 2017, Novosibirsk) “Teplomassoobmen i gidrodinamika v zakruchennykh potokakh”, Novosibirsk, Institut teplofiziki im. S.S. Kutateladze SO RAN, 2017, p. 16.

11. Dekterev D.A., Platonov D.V., Minakov A.V. Materialy V Mezhdunarodnoi konferentsii (Kazan ’, 19-22 October 2015) “Teplomassoobmen i gidrodinamika v zakruchennykh potokakh”, St. Petersburg, Svoe izdatel’stvo, 2015, pp. 164-165.

12. Liu T., Bai F., Zhao Z., Lin Y., Du Q., Peng Z. Large Eddy Simulation Analysis on Confined Swirling Flows in a Gas Turbine Swirl Burner. Energies, 2017, vol. 10(12), pp. 1-18. DOI:10.3390/en10122081

13. Matveev S.G., Orlov M.Yu., Abrashkin V.Yu., Zubrilin I.A., Matveev S.S. Vestnik Samarskogo gosudarstvennogo aerokosmicheskogo universiteta im. akademika S.P. Koroleva (natsional’nogo issledovatel’skogo universiteta), 2011, no. 5(29), pp. 179-187.

14. Nazukin V.A., Avgustinovich V.G., Thornber B., Aguado L.P., Tsatiashvili V.V., Koromyslov E.V. Vestnik Samarskogo gosudarstvennogo aerokosmicheskogo universiteta im. akademika S.P. Koroleva (natsional’nogo issledovatel’skogo universiteta), 2013, no. 3-1(41), pp. 197-205.

15. Nazukin V.A., Avgustinovich V.G. Vestnik Permskogo natsional’nogo issledovatel’skogo politekhnicheskogo universiteta. Aerokosmicheskaya tekhnika, 2016, no. 44, pp. 63-84. DOI: 10.15593/2224-9982/2016.44.04

16. Kozelkov A.S., Kurulin V.V., Tyatyushkina E.S., Puchkova O.L. Matematicheskoe modelirovanie, 2014, vol. 26, no. 8, pp. 81-96.

17. Zubrilin I.A., Didenko A.A., Dmitriev D.N., Gurakov N.I., Hernandez M.M. Combustion process effect on the swirled flow structure behind a burner of the gas turbine engine combustion chamber. Aerospace MAI Journal, 2019, vol. 26, no. 3, pp. 124-136.

18. Sha M., Agul’nik A.B., Yakovlev A.A. The effect of the computational mesh while mathematical modeling of the inflow of a subsonic flow onto the profile of a perspective blade with a deflectable trailing edge in a three-dimensional setup. Aerospace MAI Journal, 2017, vol. 24, no. 4, pp. 110-121.

19. Kraev V.M. About hydrodynamic unsteady turbulent flow calculation. Aerospace MAI Journal, 2010, vol. 17, no. 4, pp. 125-130.

20. Ryzhen’kov V.O., Ivashchenko V.A., Mullyadzhanov R.I. Izvestiya Tomskogo politekhnicheskogo universiteta. Inzhiniringgeoresursov, 2016, vol. 327, no. 6, pp. 55–63.