Influence de la répartition de la charge sur les performances d'une turbomachine axiale contrarotative

Abstract

Due to high requirements of energy consumption level, weight and dimension restriction in many industrial fields, compact axial turbomachines are expected. Counter-rotating axial-flow fans may be a solution. The design and optimization of such a system is a scientific and technological challenge, particularly because of very complex phenomena produced by the interaction of highly unsteady flows. Experimental measurements of overall performance, wall pressure fluctuations and velocity have been performed on a reference system. The design method has first been validated, and the effects of the distance between the two rotors and of the rotational speed ratio have been studied. The results show a surprising optimum operating range. We present a set of results comparing the performances of four contra-rotating systems that have been designed for the same operating point. These stages differ in their distribution of load between the rotors, and in the slope of the characteristic of their first rotor. In addition, we explore the effects of these parameters on the robustness of the performance of the stage with respect to the variation of the speed ratio of the two rotors.