Document Type : Original Article


Mechanical Power Engineering Department, Faculty of Engineering, Port Said University, Egypt


Secondary flow remains a challenging task for both the researchers who pursue diligently their efforts to develop an improved understanding of the mechanisms of loss production and for the designers who endeavor to minimize the impact of losses on turbine performance by controlling the secondary flow and by reducing their interference with the main flow. As an extension to control secondary flows and losses reduction in turbine blades, this work introduces an experimental investigation which was carried out to establish the effect of endwall injected air on a turbine blade losses by different air jets location through flow channel between two consecutives blades and also with different inlet air flow speed at subsonic flow conditions through the blade cascade. Tests were conducted by using a linear cascade of turbine blades. The cascade was fixed on a wind tunnel and working as air flow supply. Measurements of wall static pressure on the pressure and suction sides of the blades, the total pressure at flow passage exit section and determination of flow loss for blade profiles are presented. The results showed readings changes due to the alteration of location and speed of endwall air jets. It is found that, the best results were recorded in the case of endwall air jets location at suction side of the tested blade with M = 0.12. Air jets successfully diverts the path of the passage vortex and decreases its effect on the suction side blade by creating higher static pressure on pressure side (10.2% higher in blade pressure loading than on case without air injection application) and preventing boundary layer separation at suction side and also This modification has a significant effect to create a homogeneous pressure distribution through blade chordwise and hence reducing the possibilities of flow vortices existence then reducing the undesirable effects of secondary flow.