APPLICATION OF COMPOUND LEANED BLADES TO CONTROLLING SECONDARY FLOW

Mechanism of controlling secondary flow by using positive leaned blades or compound leaned blades is considered in this paper.The conclusion is that the positive leaned blades produce a converse radial pressure gradient at the hub.Under its action the low energy fluid in the blade surface boundary layer is migrated from hub to midspan,the blade to blade transverse pressure gradient is reduced,passage vortices is weakened and hence the secondary flow losses are decreased.A computation of the compound leaned blades applied to guide vanes in a small engine has been performed as an example.Its results show that by comparison with conventional blades,the degree of reaction and static pressure at the hub of the compound leaned blades are increased,the flow behavior near the hub of working blades is improved;the degree of reaction at the tip is reduced and therefore the leakage losses are cut down too.It is proved that the positive leaned or the compound leaned blades are applicable to controlling the spanwise pressure gradient,the stage reaction and the downstream effect of the secondary flow.