Laser Anemometer Measurements in a Compressor Rotor Flowfield at Off-Design Conditions

The measurement of the flowfield at the peak pressure rise condition in an axial flow compressor rotor is reported in this paper. The inviscid flow measurement was carried out using a laser Doppler velocimeter and the blade boundary layers were measured using a two-sensor hot-wire pobe. The blade-to-blade distribution of velocities at several axial and radial locations are plotted, interpreted, and compared with the conditions existing at a lower (design) flow coefficient. The leading-edge effects on inviscid flow are found to be appreciable. The flowfield is dominated by inviscid flow at most radial locations and the blade boundary-layer thickness is found to be appreciable in the tip region. The flow near the tip is dominated by leakage and its influence is more severe at the peak pressure rise condition. Nomenclature local lift coefficient based on local inlet dynamic head of the relative flow static and stagnation pressure of absolute flow pressure and suction surfaces, respectively radius ratio, r/rt blade spacing streamwise, normal, and radial coordinate directions blade tip speed absolute and relative flow velocity normalized by the blade tip speed resultant velocity on the cylindrical surface, pfpQ