Numerical study on the clocking effect of a low-speed compressor with different inter-blade-row gaps

Based on the experimental results of a low speed compressor, two-dimensional (2D) unsteady numerical simulation has been applied to study the performance variation of low speed compressor with different inter-blade-row gaps. The result of simulation shows that the compressor efficiency is increased by more than 1% when the axial gap is decreased to be 33% of the original gap. Except for the first static row, the flow losses in the rear three blade rows are all reduced, obviously in the first rotor row in this case. It is analyzed that the enhancement of potential isturbed flow caused by the axial gap reduction will produce an unsteady flapping wing phenomena, which improves the flow significantly in the first rotor row. The conclusion is given that properly decreasing the axial clearance can reduce the loss of downstream blade row caused by unsteady disturbances.