Abstract
This paper reports the results of experimental investigations carried out to reduce pressure losses by means of two-dimensional roughness elements (in the form of stainless steel tubes of different diameters). The roughness elements are fixed at various axial stations on the suction surface of 120° turning, 175 mm chord, impulse turbine rotor blades. Flow measurements are carried out at the exit of the cascade at five axial stations, using a five-hole probe operating in non-nulling mode. In addition, the blade surface static pressure distribution is measured. The data from the five-hole probe measurements are used to calculate pressure, velocity and flow angle distributions at the cascade exit and these results are used to calculate mass averaged values and integral parameters such as wake half-width, loss coefficient, etc. The static pressure distribution is altered very little except near the roughness element. The lift coefficient remains almost constant for all configurations and the drag coefficient is reduced for some configurations. The non-dimensional total pressure defects in the wake for all configurations followed Gaussian distribution. A two-dimensional roughness element of 0.6 mm diameter placed at 0.65 chord on the suction surface showed an appreciable reduction in pressure losses.
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Hoheisel, H., Kiock, R., Lichtfuss, H.J. and Fottner, L., Influence of free stream turbulence and blade pressure gradient on boundary layer and loss behavior of turbine cascades. Trans. ASME, J. Turbomachinery 109(2) (1987) 210-219.
Hebbel, H.H., Uber den Einfluss der Machzahl und der Reynoldszahl auf die aerodynamischen Beiwerte von Turbinenschaufelgittern ber verschiedener Turbulenz der Stromung. Forschg. Ing. Wesen 30 (1964) 17-28.
Nieuwstadt, F.T.M., Wolthers, W., Leijdens, H., Krishna Prasad, K. and Schwarz-van Manen, A., The reduction of skin friction by riblets under the influence of an adverse pressure gradient. Exp. Fluids 15(1) (1993) 17-26.
Troung, T.V. and Pulvin, Ph., Influence of wall riblets on diffuser flow. Appl. Sci. Res. 46(3) (1989) 217-227.
Viswanath, P.R. and Mukund, R., Turbulent drag reduction using riblets on a supercritical airfoil at transonic speeds. AIAA J. 33(5) (1995) 945-947.
Treaster, A.L. and Yocum, A.M., The calibration and application of five-hole probes. ISA Trans. 18(3) (1978) 23-34.
Sitaram, N., Lakshminarayana, B. and Ravindranath A., Conventional probes for the relative flow measurement in a rotor blade passage. ASME, J. Engrg. for Power 101(2) (1981) 406-414.
Hoheisel, H., Ergebnisse experimenteller Untersuchungen an Turbinengittern mit vorgegebener Druckverteilung. In: DGLR Symposium on Neue Beschaufelungskonzepte für axiale Turbomaschinen (1984).
Horlock, J.H., Axial Flow Turbines. Butterworths, London (1966).
Ravindranath, A. and Lakshminarayana, B., Mean velocity and decay characteristics of the near and far wake of a compressor rotor blade of moderate loading. ASME, J. Engrg. for Power 100(3) (1980) 535-548.
Sitaram, N., Effect of stage loading on endwall flows in an axial flow compressor rotor. ASME Paper 88-GT-11 (1988).
Ramjee, V., Tulapurkara, E.G. and Rajasekar, R., Development of airfoil wake in a longitudinally curved stream. AIAA J. 26(8) (1988) 948-953.
Lieblein, S. and Roudebush, W.H., Theoretical loss relations for low speed two-dimensional cascade flow. NASA TN 3662 (1956).
Raj, R. and Lakshminarayana, B., Characteristics of the wake behind a cascade of airfoils, J Fluid. Mech. 61(4) (1973) 707-730.
Kool, P., De Ruyck, J. and Hirsch, Ch., Three-dimensional flow and blade wake in an axial plane downstream of an axial compressor rotor. ASME 78-GT-66 (1978).
Reynolds, B. and Lakshminarayana, B., Characteristics of lightly loaded fan rotor blade wake. NASA CR 3188 (1979).
Ravindranath, A. and Lakshminarayana, B., Rotor wake mixing effects downstream of a compressor rotor. ASME, J. Engrg. for Power 104(2) (1982) 202-210.
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Sitaram, N., Govardhan, M. & Murali Krishna, V. Loss Reduction by Means of Two-Dimensional Roughness Elements on the Suction Surface of a Linear Turbine Rotor Cascade. Flow, Turbulence and Combustion 62, 227–248 (1999). https://doi.org/10.1023/A:1009945110174
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DOI: https://doi.org/10.1023/A:1009945110174