Evolution of rotor wake in swirling flow

Basman E1-Hadidi I and Hafiz Atassi 2University of Notre Dame, Notre Dame, IN 46556andEdmane Envia _ and Gary Podboy 4NASA Glenn Research Center, Cleveland, OH 44135AbstractA theory is presented for modeling the evolution of rotor wakes as a function of axial distancein swirling mean flows. The theory, which extends an earlier work to include arbitrary radial dis-tributions of mean swirl, indicates that swirl can significantly alter the wake structure of the rotorespecially at large downstream distances (i.e., for moderate to large rotor-stator spacings). Usingmeasured wakes of a representative scale model fan stage to define the mean swirl and initial wakeperturbations, the theory is used to predict the subsequent evolution of the wakes. The results in-dicate the sensitivity of the wake evolution to the intial profile and the need to have complete andconsistent initial definition of both velocity and pressure perturbations.