Parametric study of injector radial penetration on stalling characteristics of a transonic fan

This paper reports on a numerical investigation of the radial penetration of injectors in a high-speed axial fan. Four annular injectors with different radial heights were placed over the casing and choke to stall unsteady computations were performed for each case. Results reveal that as long as the blade is “wall-stall” (i.e., stall is initiated from the tip), range extension is mostly due to injecting into the tip of the blade. If the injector is located close enough to the blade, however, increasing the radial penetration of the injector can provide considerable range extension by changing the rotor stalling mode from “wall-stall” to “blade-stall”. The rotor with zero tip clearance has been also studied in the current work. Results show that endwall injection can desensitize the compressor to the detrimental effects of the tip clearance.