Lessons from rotor 37

NASA rotor 37 was used as a ‘blind’ test case for turbomachinery CFD by the Turbomachinery Committee of the IGTI. The rotor is a transonic compressor with a tip speed of 454 m/s (1500 ft/s) and a relatively high pressure ratio of 2.1. It was tested in isolation with a circumferentially uniform inlet flow so that the flow through it should be steady apart from any effects of passage to passage geometry variation and mechanical vibration. As such it represents the simplest possible type of test for three-dimensional turbomachinery flow solvers. However, the rotor still presents a real challenge to 3D viscous flow solvers because the shock wave-boundary layer interaction is strong and the effects of viscosity are dominant in determining the flow deviation and hence the pressure ratio. Eleven ‘blind’ solutions were submitted and in addition a ‘non-blind’ solution was used to prepare for the exercise. This paper reviews the flow in the test case and the comparisons of the CFD solutions with the test data. Lessons for both the Flow Physics in transonic fans and for the application of CFD to such machines are pointed out.