Experimental test of a compressor cascade with non-axisymmetric end-wall contouring at off-design conditions

End-wall losses in axial flow turbomachinery, particularly in compressors, constitute a significant challenge due to their adverse impact on overall efficiency. Pioneering works in this field have demonstrated the potential for end-wall loss reduction by improving end-wall profiles. However, many previous efforts have concentrated solely on design conditions, largely disregarding the behavior of these contoured end-walls under off-design conditions-where compressors often operate. This study investigates the adaptability of a non-axisymmetric endwall contour, performing well under design conditions, to off-design scenarios, focusing particularly on the influence of Mach numbers on its ability to control corner separation effects. Experimental research was conducted using a combination of surface static pressure taps and aerodynamic probes to quantitatively and qualitatively analyze the effect of the non-axisymmetric end-wall contour on reducing losses. Quantitative outcomes demonstrate a notable decrease in overall losses in the blade cascade due to this end-wall contour. For all tested Mach numbers, the average loss reduces by 4% at 0 degrees of incidence, with a 0.9 degrees decrease in deviation angle, and an 8% average loss reduction at 5 degrees of incidence, accompanied by a 1.5 degrees decrease in deviation angle. Qualitative findings suggest that the mechanism by which the non-axisymmetric end-wall contour reduces blade cascade losses involves the enhancement of pitchwise pressure gradients. This enhancement redirects lowmomentum fluid toward the blade's suction surface, diminishing its reach in the pitchwise direction. However, it also intensifies loss in the low-momentum fluid core. Additionally, the presence of a convex feature in the rear section of the blade passage mitigates pitchwise static-pressure gradients, effectively ameliorating secondary flows and preventing their further decline. Moreover, it was observed that the control effectiveness of the endwall contour on corner separation increases with higher Mach numbers.