Incidence Effects on Wake-Induced Transition on an Axial Compressor Blade

Boundary-layer transition phenomena on an outlet stator blade of a 1.5-stage axial compressor were observed with a closely packed array of hot-e lm sensors. Synchronized sampling was used to identify periodic features associated with the passage of rotor wakes; ensemble-averaged wall shear stress, unsteadiness, and intermittency are presented. Three e ow cases at different blade incidence are examined to determine the effects of surface pressure distribution on the transition behavior. Wake-induced transitional strips occur in all cases; their nature and the relative strength of associated calming periods and periodic unsteadiness are strongly ine uenced by the blade incidence. A signie cant difference in character between wake-induced transition effects on the suction and pressure surfaces is observed. Periodic phenomena are still evident when transition is initiated within a midchord separation bubble.

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