COMPRESSOR BLADE ROW UNSTEADY AERODYNAMIC RESPONSE TO ATTACHED AND SEPARATED FLOW FORCING FUNCTIONS

A series of experiments are performed to investigate the fundamental flow forcing function phenomena generating different blade row gust responses, in particular attached and separated flow forcing functions. Furthermore, unsteady linear theory gust requirements are considered. Two NACA 0024 airfoils are installed in an extensively instrumented axial flow compressor inlet to generate the periodic 2-E unsteady aerodynamic forcing functions to the first stage rotor. These forcing functions are measured with a rotating cross hot-wire, with the resulting rotor blade row unsteady aerodynamic gust response measured with dynamic pressure transducers embedded in the rotor blade over a range of steady loading levels. The rotor blade gust response unsteady aerodynamic data are then correlated with appropriate predictions. These experiments revealed the new result that the forcing function generator fluid dynamics is significant with regard to the resulting unsteady aerodynamic gust response of the downstream airfoil row. Namely, the degree of correlation of the rotor blade unsteady gust response data with linear theory is closely related to the characteristics of the forcing function gust generating the response.