Effect of Tip Injection on an Axial Compressor using Airflow Recirculation - Numerical Investigations

Abstract

International audienceIn this paper the results of a numerical analysis concerning the impact of a passive flow control technique on a 1.5-stage axial compressor are presented. In order to examine the effects occurring due to the application of discrete tip blowing in the rotor domain, unsteady flow simulations are conducted. In low speed axial compressors the rotor blade tip area is critical concerning the effect of flow separation because of low momentum fluid in the endwall boundary layer and the rotor tip leakage vortex. These flow effects cause a loss in efficiency and are furthermore responsible for a cutback in the compressor working range. As a potential method to increase the working range the impact of recirculation ducts in the rotor casing is investigated in this study. Due to the static pressure gradient over the rotor passage fluid flows through the recirculation ducts, reenergizing the boundary layer at the leading edge of the rotor tip. Their design and positioning take the limited available space in aeroengines into account. This survey focuses on the impact of the tip blowing jet on the rotor performance, in particular the interaction of the recirculated mass flow and the tip leakage vortex will be discussed