CFD-model of Vaneless Diffuser of Centrifugal Compressor

The centrifugal compressor design involves the use of approximate engineering techniques based on mathematical modeling. One of such techniques is the universal modeling method, which proves to be practically applicable. Having generalized a series of CFD calculations, we used a mathematical model in the latest version of the compressor model to calculate flow parameters in vaneless diffusers. The diffuser model was identified based on the results of experimental studies of average-flow model stages carried out at SPbPU. The model is also used to calculate Clark low-flow centrifugal compressor stages with narrow diffusers with a relative width in the range of 0.5--2.0 %. For these stages, the developed mathematical model showed insufficient efficiency, since the dimensions of the diffusers go beyond the limits of its applicability. To solve this problem, we calculated a series of vaneless diffusers with a relative width in the range of 0.6--1.2 % in the ANSYS CFX software package. Relying on the results of CFD calculations, we plotted the gas dynamic characteristics of the loss coefficients and changes in the flow angle depending on the flow angle at the inlet to the vaneless diffuser. To process the calculated data, the method of regression analysis was applied, with the help of which a system of algebraic equations was developed that connects geometric, gas-dynamic parameters and similarity criteria. The obtained equations are included in a new mathematical model of the universal modeling method for calculating the flow parameters of vaneless diffusers. Comparison of the calculated gas-dynamic characteristics according to the new model with experimental data showed the average error of modeling the calculated (maximum) efficiency equal to 1.08 %

The study was supported by the grant of the President of the Russian Federation for young candidates of sciences MK-1893.2020.8.The calculations were carried out using the supercomputer center "Polytechnic", SPbPU

References

[1] Startsev A., Fokin Yu., Steshakov Eu. CFD design and analysis of a compact single-spool compressor for a heavy transport helicopter’s powerplant. 29th ICAS Cong., 2014. Available at: http://www.icas.org/icas_archive/icas2014/data/papers/2014_0928_paper.pdf (aссessed: 25.06.2018)

[2] Xu C., Chen W.J. Computational analysis on a compressor blade. Int. Conf. Jets, Wakes Separated Flow. Toba-shi, Mie, Japan, 2005.

[3] Kosprdova J., Oldrich J. The development of centrifugal turbo compressor stage using CFD. 20th Int. Conf. Hydraulics and Pneumatics, 2008. Available at: https://ru.scribd.com/document/45780046/000000194-f (accessed: 25.06.2018).

[4] Puzyrewski R., Galerkin Y.B., Flaszynski P. Direct and inverse numerical calculation for the tested centrifugal impeller. XL Int. Tagung Forschung Praxis und Didaktik im Modernen Maschinеnbau. Germany, 2001, pp. 41--48.

[5] Mosdzien M., Enneking M., Hehn A., et al. Influence of blade geometry on secondary flow development in a transonic centrifugal compressor. J. Glob. Power Propuls. Soc., 2018, vol. 2, no. 1, pp. 429--441. DOI: https://doi.org/10.22261/JGPPS.I1RSJ3

[6] Sorokes J.M., Hutchinson B.R. The practical application of CFD in the design of industrial centrifugal compressors. Challenges and Goals in Pipeline Compressors, 2000, PID, vol. 5, pp. 47--54.

[7] Sorokes J.M., Nye D.A., D’Orsi N., et al. Sidestream optimization through the use of computational fluid dynamics and model testing. Proc. 29th Turbomachinery Symp. Texas, A&M, 2000, pp. 21--29.

[8] Guidotti E. Towards centrifugal compressor stages virtual testing. Ph. D. Thes. Universita degli Studi di Bologna, 2014.

[9] Kryllowicz W., Swider P., Kozanecki Z., et al. Technical and aerodynamical aspects of a high pressure synthesis gas turbocompressor modernization. 12th Europ. Conf. on Turbomachinery Fluid Dynamics and Thermodynamics, 2017. Available at: https://www.euroturbo.eu/paper/ETC2017-171.pdf (accessed: 25.06.2018).

[10] Matas R., Syka T., Lunacek O. Numerical and experimental modelling of the centrifugal compressor stage--setting the model of impellers with 2D blades. EPJ Web Conf., 2017, vol. 143, art. 02073. DOI: https://doi.org/10.1051/epjconf/201714302073

[11] Galerkin Y., Voinov I., Drozdov A. Comparison of CFD-calculations of centrifugal compressor stages by NUMECA Fine/Turbo and ANSYS CFX programs. IOP Conf. Ser.: Mater. Sc. Eng., 2017, vol. 232, art. 012044. DOI: https://doi.org/10.1088/1757-899X/232/1/012044

[12] Borovkov A.I., Voinov I.B., Nikitin M.A., et al. Experience of performance modeling the single-stage pipeline centrifugal compressor. AIP Conf. Proc., 2019, vol. 2141, no. 1, art. 030051. DOI: https://doi.org/10.1063/1.5122101

[13] Borovkov A.I., Voinov I.B., Galerkin Yu.B., et al. Experimental characteristic simulation for two-stage pipeline centrifugal compressor. IOP Conf. Ser.: Mater. Sc. Eng., 2019, vol. 604, art. 012052. DOI: https://doi.org/10.1088/1757-899X/604/1/012052

[14] Marenina L.N. CFD wind tunnel tests of centrifugal stage return channel vane cascades. Kompressornaya tekhnika i pnevmatika [Compressor Technology and Pneumatics], 2016, no. 3, pp. 27--35 (in Russ.).

[15] Marenina L.N. CFD wind tunnel tests of centrifugal stage return channel vane cascades. Kompressornaya tekhnika i pnevmatika [Compressor Technology and Pneumatics], 2016, no. 3, pp. 27--35 (in Russ.).

[16] Galerkin Y., Solovyeva O.A. Flow behavior and performances of centrifugal compressor stage vaneless diffusers. Int. J. Mech. Aerosp. Ind. Mech. Manuf. Eng., 2015, vol. 9, no. 1, pp. 128--133.

[17] Solov’yeva O.A. Matematicheskaya model’ dlya rascheta gazodinamicheskikh kharakteristik i optimizatsii bezlopatochnykh diffuzorov tsentrobezhnykh kompressornykh stupeney. Dis. kand. tekh. nauk [Mathematical computational model of gas-dynamic properties and optimization of vaneless diffuser in centrifugal compressor stages. Cand. Sc. (Eng.). Diss.]. St. Petersburg, SpbPU Publ., 2018 (in Russ.).

[18] Cumpsty N.A. Compressor aerodynamics. Longman, 1989.