Testing Protruding Studs As a Form of Casing Treatment on a Transonic Turbofan: A Computational Study

Abstract

This paper presents the findings of an ongoing CFD study of using protruding studs as a form of casing treatment on a transonic turbofan stage. Simulations have been performed on the subject turbomachine with and without the casing treatment in order to validate computations with available experimental results and to compute any difference in performance. The results of the simulations with the casing treatment suggest that protruding studs have the potential to extend the stall margin of the turbofan while resulting in a slight reduction in pressure rise and efficiency. From the use of an initial configuration of studs, the computed increase in stall margin based on mass flow rate was 5.46%, and the greatest decrease in pressure ratio and adiabatic efficiency were 0.25% and 1.59%, respectively. Flowfield visualizations of simulations at computed near-stall conditions without casing treatment show regions of low momentum flow near the casing in the rotor blade passage, and low momentum regions near the hub in the stator section. Visualization from simulations with casing treatment at computed near-stall conditions show a large blockage imposed by the studs in the rotor blade passage, and a low momentum region near the casing in the stator section. Computed performance maps obtained from using other configurations of studs suggest that further increase in stall margin is possible at other levels of protrusion of the studs.