Experimental Study on Aerodynamic Performance and Flow Structure of a Diffuser Cascade with Splitter Blades

For diffuser cascade respectively with 45 degree turning angle and with splitter blades,aerodynamic performance of the cascade was measured under working conditions and at different attack angles,while flow structure inside the cascade studied under corresponding working conditions through PIV experiments.Results show that the pressure gradient from pressure surface to suction surface of large blade has been lowered substantially after small blade is added,and the load on large blade is reduced also;under design conditions,the lag angle of cascade flow can still be calculated according to Howell semi-empirical formula,however,large error will be produced if the formula is used under off-design conditions;the lag angle of cascade with splitter blades shall be obviously reduced only in the case the attack angle is small,and under other conditions,little changes will be produced;the air flow separation on large-blade surface is restrained by small blade at different attack angles;the diffuser loss of cascade reduces in the process of changing the attack angle from design condition to large values.