Unsteady Aerodynamic Characteristics of Annular Cascade Oscillating in Transonic Flow : 1st Report, Measurement of Aerodynamic damping with Freon Gas Controlled-oscillated Annular Cascade Test Facility

Abstract

This paper describes a developed annular cascade wind tunnel and newly advanced experimental techniques for investigating aerodynamic damping acting on an annular cascade in a transonic flow and at a high reduced frequency. For the study, a high speed mechanical drive system has been developed and Freon gas has been chosen as working fluid in the wind tunnel. The drive system can controlled-oscillate all the 16 blades composing an annular cascade in torsional mode at a constant amplitude and at a constant interblade phase angle up to a frequency of 500 Hz. This frequency corresponds to a reduced frequency of 1.2 (at M=1.4 and C=72mm). Three auxiliary apparatus also have been developed for aerodynamic damping measurement and flow visualization. With the experimental installations and the techniques, a lot of aerodynamic damping data have been collected on compressor and turbine cascades.