Beneficial Use Of Unsteady Blade Row Interaction In Reducing Rotor Aerodynamic Force

The research of unsteady flowfield in turbomachinery has been populated nowadays.As a typical unsteady flow phenomenon,clocking effect has attracted more and more attention.But quantities of articals were still focoused on the influence of clocking effect on improving compressor/fan's isentropic efficiency,so the benefit of airfoil indexing haven't been totally developed.This paper demonstrated how to reduce rotor balde unsteasdy aerodynamic force that causes HCF problem by properly shifting the IGV and stator blade circumferential position.The computational research was conducted in a 1.5-stage compressor, using NUMECA software.Analysis of the blade pressure coeffiecient and local balde aerodynamic force illustrated the influence of upstream wakes and downstream potential effect on rotor balde force.Several operating conditions were investigated to determine the impact of rotor blade unsteady aerodynamic force reduction by clocking effect under varied operating conditions.The results showed that ,at a given rotation speed ,the degree of clocking effect in reducing rotor balde unsteady aerodynamic force were more and more obviously with increased inlet flow coefficient,and at a given inlet flow coeffiecient,the degree was decreased and then increased with increasing rotation speed.Howere,the minimum and maximum balde unsteady aerodynamic force were independent of compressor operating conditions. The minimum balde force occurred when upstream wakes swept against rotor blade leading edge conincide with downstream stator positioned backward of the rotor trailing edge,while the maximum rotor blade force occurred when it's positioned in the backward of the mid of rotor passage.