Combined/simultaneous gust and oscillating turbine row unsteady aerodynamics in subsonic flow

This paper presents, for the first time, a detailed experimental comparison between combined and simultaneous motion- and gust-induced unsteady aerodynamic response of a turbine cascade. Experiments are performed in a non-rotating annular test facility to investigate the local validity of the linearised treatment of the forced response problem. The gust-response unsteady aerodynamics are experimentally modelled using rotating gust generators. The torsion mode unsteady aerodynamics of a turbine cascade are investigated by controlling the motion of all 20 blades. Combined gust and oscillating blades unsteady aerodynamics are obtained by the linear superposition of the oscillating blade row and the gust-response unsteady aerodynamics measured separately. Simultaneous gust- and motion-induced unsteady aerodynamic responses are obtained by oscillating the blades in presence of the 13 or 22 per revolution forcing function. The linear superposition principle could be shown to be locally valid for the investigated flow and vibration conditions.