Document Type: Research Paper

Authors

1 School of Mechanical Engineering, Arak University of Technology, Arak , Iran

2 School of Mechanical Engineering, Iran University of Science and Technology, Tehran 16846-13114, Iran

Abstract

Characteristics of rotor blade tip clearance flow in axial compressors can significantly affect their performance and stable operation. It may also increase blade vibrations and cause detrimental noises. Therefore, this paper is contributed to investigate tip leakage flow in a low speed isolated axial compressor rotor blades row. Simulations are carried out on near-stall condition, which is valuable of being studied in detail. In turbomachines, flows are non-isotropic and highly three-dimensional. The reason arises from the complicated structure of bounded walls, tip leakage flows, secondary flows, swirl effects, streamlines curvatures and pressure gradients along different directions. As a result, accurate studies on tip leakage flow would be accompanied by many challenges such as adopting suitable turbulence models. So, investigations are carried out numerically utilizing two well-known turbulence models of k-ε and k-ω-SST, separately. It is shown that the k-ε model yields poor results in comparison to the k-ω-SST model. To realize reasons for this discrepancy, turbulence parameters such as turbulent kinetic energy, dissipation and eddy viscosity terms at the tip clearance region were surveyed in detail. It is found out that estimation for eddy viscosity term is too high in the k-ε model due to excessive growth of turbulent kinetic energy, time scale, and lack of effective damping coefficient. This leads to dissipation of vortical structure of flow and wrong estimation of flow field at the rotor tip clearance region. Nevertheless, k-ω-SST turbulence model provides results consistent with reality.

Graphical Abstract

Keywords

Main Subjects

[1]     J. D. Denton, “Loss mechanisms in turbomachinery,” ASME Journal of Turbomachinery, Vol. 115, No. 4, pp. 621-656, (1993).

[2]     J. Dunham, “CFD validation for propulsion system components,”AGARD-AR-355, (1998).

[3]     Y. Hwang, and S Kang, “Flow and Performance Calculations of Axial Compressor near Stall Margin,” The 10th Asian International Conference on Fluid Machinery, Paper ID AICFM0205, (2010).

[4]     H. W. Zhang, X. Y. Deng, F. Lin, Chen, and W. G. Huang, “A Study on the Mechanism of Tip Leakage Flow Unsteadiness in an Isolated Compressor Rotor,” ASME Paper GT2006-91123, (2006).

[5]     J. Du, F. Lin, Zhang, H. W., and Chen, J. Y., 2008, “Numerical Investigation on the Originating Mechanism of Unsteadiness in Tip Leakage Flow for a Transonic Fan Rotor, ” ASME Paper GT2008-51463, (2006).

[6]     J. Du, F. Lin, H. Zhang, and J. Chen, “Numerical Simulation on the Effect of Tip Clearance Size on Unsteadiness in Tip Clearance Flow,” Journal of Thermal Science, Vol. 17, No. 4, pp. 337-342 (2008).

[7]     Z. T. Tong, F. Lin, J. Y. Chen, and C. Q. Nie, “The Self-Induced Unsteadiness of Tip Leakage Vortex and Its Effect on Compressor Stall Inception,” ASME Paper GT2007-27010, (2006).

[8]     S. Geng, F. Lin, Chen, J., Zhang, H. and Lei, H, “Circumferential Propagation of Tip Leakage Flow Unsteadiness for a Low-Speed Axial Compressor,” Journal of Thermal Science, Vol. 18. No. 3, pp. 202-206, (2009).

[9]     S. J. Geng, “Numerical Investigation on the Unsteady Response of Compressor Tip Leakage Flow to Discrete Micro Tip Injection and Its Effect on Stability Enhancemen,” PhD Thesis, Graduate School of the Chinese Academy of Sciences, (2007).

[10]    F. R. Menter, M. Kuntz, R. e Langtry, “ Ten years of industrial experience with the sst turbulence model,” in K. Hanjalic, Y. Nagano e M. Tummers (eds.), Turbulence, Heat and Mass Transfer 4, Begell House, Inc, (2003).

[11]   P. V. Ramakrishna, and M. Govardhan, “Stall Characteristics and Tip Clearance Effects in Forward Swept Axial Compressor Rotors,” Journal of Thermal Science, Vol. 18, No. 1, pp. 40-47, (2009).

[12] N. Gourdain, F. Leboeuf, “Unsteady Simulation of an Axial Compressor Stage with Casing and Blade Passive Treatments,” Journal of Turbomachinery, 131, 21013-1, (2009).

[13]   G. Legras, Gourdain, N. and Trebinjac, I, “Numerical Analysis of the Tip Leakage Flow Field in a Transonic Axial Compressor with Circumferential Casing Treatment,” Journal of Thermal Science, Vol. 19, No. 3, pp. 193-197 (2010).

[14]   K. Yamada, K. Funazaki, and M. Furukawa, “The behavior of tip clearance flow at near-stall condition in a transonic axial compressor rotor,” ASME. GT2007-27725, (2007).

[15]   K. Yamada, K. Funazaki , “ Numerical Investigation Of Relation Between Unsteady Behavior Of Tip Leakage Vortex And Rotating Disturbance In A Transonic Axial Compressor Rotor,” ASME Turbo Expo, Power for Land, Sea and Air, (2008).

[16] Glanville, P. “Investigation Into Core Compressor Tip Leakage Modeling Techniques Using 3D Viscous Solver,” ASME Turbo Expo, GT2001-0336, (2001).

[17]   M. G. Turner, and I. K. Jennions, “An Investigation of Turbulence Modelling in Transonic Fans Including a Novel Implementation of an Implicit k-ε Turbulence Model,” ASME Journal of Turbomachinery, Vol. 115, No. 2, pp. 249–260, (1993).

[18] Y. Lui, X. Yu, and B. Lui, 2008, “Turbulence Models Assessment for Large-Scale Tip Vortices in an Axial Compressor Rotor,” Journal of Propulsion and Power, Vol. 24, No. 1, (2008).

[19]   J. E. Bardina, P. G. Huang, T. J. e Coakley, “Turbulence modeling validation, testing, and development,” Technical report, NASA TM 110446, (1997).

[20]   Y. Ito, T. Watanabe, T. e Himeno, “Effect of end wall contouring on flow instability of transonic compressor,” International Journal of Gas Turbine, Propulsion and Power Systems, Vol. 2, No. 1, pp. 24-29, (2008).

[21]   E. Benini, R. e Biollo, “Aerodynamics of swept  and  leaned transonic   compressor-rotors,” Applied Energy, Vol. 84, No.10, pp.1012-1027, (2007).

[22]   W. J. Calvert, R. B. e Ginder, “Transonic fan and compressor design. Proceedings of the Institution of Mechanical Engineers Part C-Journal of Mechanical Engineering Science, Vol. 213, No.5, pp. 419-436, (1999).

 [23] M. R. Simoes, B. G. Montojos, N. R. Moura,    and   J.    Su,    “ Validation   of turbulence models for simulation of axial flow compressor,” Proceedings of 20th International Congress of Mechanical Engineering, November 15-20, 2009, Gramado, RS, Brazil, (2009).

[24]   L. Dailey, “Simulating Laminar-Turbulent Transition with a Low Reynolds Number k-ε Turbulence Model In a Navier-Stokes Flow Solver,” MS Thesis, University of Cincinnati, (1993).

[25]   L. Merz, “A Numerical Study of a Transonic Compressor Rotor at Large Tip Clearance,” MS Thesis, University of Cincinnati, (2003).

[26]   M. Inoue, M. Kuroumaru, and M. Fukuhara, “Behavior of Tip Leakage Flow behind an Axial Compressor Rotor,” ASME Journal of Turbomachinery,Vol. 108, No. 1, pp.7-14, (1986).

[27]   Furukawa, M., Inoue, M., Saiki, K. and Yamada, K., “The Role of Tip Leakage Vortex Breakdown in Compressor Rotor Aerodynamics”, Journal of Turbomachinery, Vol. 121, No. 3, pp. 469-480, (1999).

[28]   Launder, B., Kato, M., “Modeling Flow-induced oscillations in turbulent flow around a square cylinder,” ASE FED, Vol. 157, pp. 189-199, (1993).

[29]   Medic, G., Durbin, P., 2002, “Toward Improved Prediction of Heat Transfer on Turbine Blades,” ASME Journal of Turbomachinery, Vol. 124, No. 2, pp.187 -192, (2002).

CAPTCHA Image