Optimization strategy for a single-stage axisymmetric hub endwall in axial compressor by a modified transonic area rule

The secondary loss is the primary factor limiting the performance of highly loaded compressors. As inspired by the transonic area rule used in optimization of airplane fuselage, considering the similarities of the blockage effect induced by wing to fuselage and the blockage induced by blade to flow channel, the idea of using the transonic area rule method in compressor hub profile modification has been proposed and discussed. Some related analyses are investigated due to the failure of a direct application of the transonic area rule, which includes flow field analyses, the study of related parameters and a sensitivity evaluation of eleven control parameters on the adiabatic efficiency of the compressor. Then, two parameters (rotor maximum concave displacement ratio ΔZ‾_R and magnification ratio of rotor hub leading edge l¯_1R) which have great influence on the compressor efficiency are chosen to modify the transonic area rule and to establish a new optimization guideline in the optimization of compressor hub profile. After all, the developed optimization method is applied to the first stage of a four-stage embedded compressor with an achievement of 0.97% peak efficiency rise without any penalty of total pressure ratio. Based on the numerical results, the main reasons for the peak efficiency rise are also presented and discussed.