AEROELASTIC TAILORING FOR ROTOR BLADES OF TRANSONIC SWEPT FANS

In order to raise the fan stage pressure,as an important measure to enhance engines thrust/weight ratio,there are two restrictive factors:First of all,the increase of rotor tip wheel speed will strengthen the shock waves in rotor passages,which decrease the efficiency.Then the strengthened shock waves could induce the onset of stall flutter.For the turbofans with small bypass ratio,the stall flutter is the main type of aeroelastic instabilities in the transonic fans.Both the above-mentioned two restrictive factors for raisng the stage pressure ratio are correlated closely with 3D shock wave structure and the largescale separation zone induced mainly by 3D interaction of the shock wave with boundary layer.However,the 3D shock wave structure inside rotor passages is correlated with the spatial curve of rotor blade leading edge closely.So,how to design the spatial curve of blade leading edge becomes an important frontier problem of the turbomachinery aerodynamics.During designing process of some modern transonic swept fans,a kind of integrated aerodynamic/aeroelastic tailoring program has been used.The aeroelastic tailoring,a main part of the integrated tailoring,is described,and an example has been shown in this paper.