NUMERICAL INVESTIGATION OF AN ANNULAR TRANSONIC COMPRESSOR CASCADE INCLUDING SECONDARY FLOWS

Abstract

Within the frame of the European Project FUTURE, an annular transonic compressor cascade dedicated to aeroelastic experiments was investigated at Ecole Polytechnique Fédérale de Lausanne. As a first part of the experimental investigations and for different inlet flow conditions, the static pressure distribution on the airfoil surface was determined at three different blade spans (20%, 50% and 90%) by static pressure taps located on both blade’s pressure and suction side along the blade chord. Parallel to the measurements, DLR performed numerical flutter simulations to predict the blade aerodynamic stability. For the computational fluid dynamics procedure, the associated steady-state flow field was computed using two different numerical setups. The first one considers the blade channel only and omits the geometrical complexity of the experimental model. The second mesh corresponds to the real test model and includes the cavity under the blade hub, thus enabling the modeling of the secondary flows. For a subsonic and a transonic flow operating condition, the steady-state CFD computations performed with both meshes are compared to the blade surface static pressure distributions measured. The results show that including the cavity in the numerical model is required to determine the steady-state aerodynamic forces active on the blades with reasonable accuracy.