Seventh South African Conference on Computational and Applied Mechanics SACAM10 Pretoria, 10−13 January 2010 c SACAM EXPERIMENTAL INVESTIGATION INTO THE UNSTEADY EFFECTS ON NON-AXISYMMETRIC TURBINE ENDWALL CONTOURING Dwain Dunn ∗,1 , Glen Snedden ∗,2 and Theodor W von Backstr ¨ om † * Aeronautical Systems DPSS CSIR, PO Box 395, Pretoria, 0001, South Africa, 1 ddunn@csir.co.za, 2 gsnedden@csir.co.za. † Department of Mechanical and Mechatronic Engineering University of Stellenbosch, Private Bag X1, Matieland 7602, South Africa twvb@sun.ac.za. Keywords: Non-axisymmetric endwalls, secondary flow, unsteady effects Abstract Turbine manufacturers are striving to develop turbines that are more efficient. One area of focus has been the control of secondary flows through the use of non-axisymmetric endwalls. The majority of development has been performed in cascades or by using computational fluid dynamics. The current investigation was carried out on a 1 1 / 2 stage low pressure turbine. The performance of a generic endwall profile was tested using 2 component hot-film anemometry. The generic endwall of Durham University was chosen for analysis It has been shown that the contouring improved the performance of the turbine. Detailed anal- ysis showed that the improved performance was due to a reduction in the rotor exit secondary velocity. The deviation of the rotor exit yaw angle from the design rotor exit yaw angle was reduced. Furthermore it was found that the passage vortex of the contoured rotor was not as tightly wrapped around the horse shoe vorticies as the annular rotor passage vortex. Due to the passage vortex being more unwrapped in the contoured case, the tip leakage flow was drawn towards the hub more. The spanwise extent of the tip leakage flows was increased, but the magnitude was reduced. 1 Introduction With the price of oil steadily increasing, turbine manufacturers are striving to improve effi- ciency. One of the methods used for this is to improve the power to weight ratio, by reducing the weight of the turbine, but maintain the specific thrust. This is usually done by increasing the blade loading,hich increases the impact of the secondary flows on the turbine efficiency.