Experimental study of the performance and stability of a low pressure axial compressor for a contra-rotating turbofan engine architecture

(eng) The new contra-rotating turbofan architecture leads to a substantial reduction of the pollutants and the noise emission of civil aircrafts. This architecture is based on two shorter fans, rotating in opposite direction at lower speed. Due to the mechanical link between the fan and the low-pressure compressor, its speed is also reduced. In order to keep the pressure ratio constant, without weight increase, the low-pressure compressor stages are designed with an unusually high loading coefficient and flow coefficient, which leads to a reduced stability margin. The purpose of this thesis is to present a complete characterization of the first stage of the low-pressure compressor for the new contrarotating turbofan architecture in terms of global performance, unsteady flow field and instability phenomena. This work will be the basis for future research in this field, considering the low number of publications on the low-pressure compressors and the absence of references concerning the low-pressure compressor of contra-rotating turbofan. The characterization is performed on a half scale model on the VKI R4 test facility. This facility is a closed loop, high speed compressor rig, allowing the investigation of the influence of the Reynolds number on the performance. The effect of a circumferential groove casing treatment on the performance, the stability and the unsteady flow field is studied. The measurements are compared to numerical simulations from various CFD codes using various turbulence models.