Experimental Investigation of Aerodynamic Response in Oscillating Cascade Blades Under Transonic Conditions

This study investigates the aeroelastic characteristics of a transonic linear cascade using an experimental approach to understand the influence of compressibility, incidence angle, interblade phase angle, and reduced frequency on flutter behavior. Vibration-related failure remains a major concern in modern turbomachinery, as thin and lightweight blades operating in transonic flow regimes are highly susceptible to aeroelastic instabilities. Controlled torsional oscillations are imposed on the blades ([Formula: see text] and [Formula: see text]) adjacent to the stationary central blade [Formula: see text] to study the effect of phase and frequency variation, while the central blade, instrumented with a fast-response load cell, measures the unsteady aerodynamic forces induced by the neighboring blade motion. The results indicate that phase variation can significantly increase instability when unsteady aerodynamic forces synchronize with blade motion, leading to reduced aerodynamic stability. In the transonic regime, passage shock further triggers the onset of choke-type flutter at low incidence angles and specific phase conditions. At a very high incidence, stall flutter helps the stability due to the interaction of upstream shock motion and the separation layer. However, frequency variation modifies temporal synchronization between blade passages; unlike phase variation, it does not influence blade stability significantly. The experimental results demonstrate that variations in incidence, reduced frequency, and phase synchronization determine the stability limits and flutter characteristics of turbomachinery blade rows.