Computational Study on Effect of Variation of Pitch-Chord on Secondary Losses in Rectilinear Turbine Cascade

Pulijala Shravya

Department of Mechanical Engineering, Birla Institute of Technology and Science, Pilani, India.

DOI: 10.4236/eng.2015.711064                

Abstract

Losses in turbine cascade are categorized as profile loss, secondary loss, tip clearance loss and annulus loss. Profile loss occurs due to development of boundary layer on surface of blade [1]. Increase in thickness of boundary layer and adverse pressure gradient increases profile loss. Secondary loss occurs due to turning of flow through flow passage which results in blowing of energy from pressure side to suction side. In turbine rotor blade suction surface leads and tip clearance loss occurs due to leakage of air from pressure side to suction side of the blade through tip clearance. Annulus loss occurs due to development of boundary layer on stationary row of blade. It also occurs in moving row of blade but in moving row of blades boundary layer is scraped by flow over the blades. This paper presents effects of variation of pitch-chord ratio on secondary loss.

Keywords

Turbine Cascade, Pitch-Chord Ratio, Secondary Losses

Conflicts of Interest

The authors declare no conflicts of interest.

References

[1]	Hodson, H.P. and Dawes, W.N. (1998) On the Interpretation of Measured Profile Losses in Unsteady Wake-Turbine Blade Interaction Studies. Journal of Turbomachinery, 120, 276-284.
[2]	Yahya, S.M. Turbines, Compressors and Fans. Tata McGraw Hill Education Private Limited, New Delhi.
[3]	Hodson, H.P. and Dominy, R.G. (1987) Three-Dimensional Flow in a Low-Pressure Turbine Cascade at Its Design Condition. Journal of Turbomachinery, 109, 177-185. http://dx.doi.org/10.1115/1.3262083
[4]	Becz, S., Majewski, M.S. and Langston, L.S. (2003) Leading Edge Modification Effects on Turbine Cascade Endwall Loss. ASME Proc. Turbo Expo, GT-2003-38898. http://dx.doi.org/10.1115/gt2003-38898
[5]	Luo, J.Q., Xiong, J.T. and Liu, F. and McBean, I. (2010) Secondary Flow Reduction by Blade Redesign and Endwall Contouring Using an Adjoint Optimization Method. Proceedings of ASME Turbo Expo 2010: Power for Land, Sea and Air GT 2010, Glasgow, 14-18 June 2010.
[6]	Mahmood, G.I., Gustafson, R. and Acharya, S. (2005) Experimental Investigation of Flow Structure and Nusselt Number in a Low Speed Linear Blade Passage With and Without Leading Edge Fillets. Journal of Heat Transfer, 127, 499-512. http://dx.doi.org/10.1115/1.1865218
[7]	Singoria, V.K. and Samsher (2013) The Study of End Losses in a Three Dimensional Rectilinear Turbine Cascade. Journal of Emerging Technology and Advanced Engineering, 3, 782.
[8]	Ning, W.E.I. (2000) Significance of Loss Models in Aerothermodynamic Simulation for Axial Turbines. Doctoral Thesis.
[9]	Cohen, H., Rogers, G.F.C. and Saravanamuttoo, H.I.H. Gas Turbine Theory. 4th Edition, Longman Group Ltd., Essex, 19.
[10]	10Wood, J.R. (1972) An Investigation of Secondary-Flow Phenomena and Associated Losses in a High-Deflection Turbine Cascade. Naval Postgraduate School, Monterey.