A 3-DIMENSIONAL SHOCK LOSS MODEL APPLIED TO AN AFT-SWEPT, TRANSONIC COMPRESSOR ROTOR

An analysis of the effectiveness of a three-dimensional shock loss mod el used in transonic compressor rotor design is presented The model wa s used during the design of an aft-swept, transonic compressor rotor. The demonstrated performance of the swept rotor, in combination with n umerical results, is used to determine the strengths and weaknesses of the model. The numerical results were obtained from a fully three-dim ensional Navier-Stokes solver. The shock loss model was developed to a ccount for the benefit gained with three-dimensional shock sweep. Comp arisons with the experimental and numerical results demonstrated that shock loss reductions predicted by the model due to the swept shock in duced by the swept leading edge of the rotor were exceeded. However, n ear the tip the loss model underpredicts the loss because the shock ge ometry assumed by the model remains swept in this region while the num erical results show a more normal shock orientation The design methods and the demonstrated performance of the swept rotor are also presente d, Comparisons are made between the design intent and measured perform ance parameters, The aft-swept rotor was designed using an inviscid ax isymmetric streamline curvature design system utilizing arbitrary airf oil blading geometry. The design goal specific flow rate was 214.7 kg/ s/m(2) (43.98 lbm/sec/ft(2)), the design pressure ratio goal was 2.042 , and the predicted design point efficiency was 94.0. The rotor rip sp eed was 457.2 m/s (1500 ft/sec). The design pow rate was achieved whil e the pressure ratio fell short by 0.07. Efficiency was 3 points below prediction, though at a very high 91 percent. Ar this operating condi tion the stall margin was 11 per-cent.