An Euler-Based Throughflow Approach for Centrifugal Compressors – Part B: Experimental Investigations and Validation

For turbomachinery design, manufacturers today need fast tools to predict the performance of an aerodynamic design with good accuracy. However, CFD tools are often cumbersome in terms of computation time and licensing costs for commercial solvers. In this context, a quasi-three-dimensional solver, called tFlow, for centrifugal compressors is presented in Part A of this paper. To validate and calibrate the model, an experimental test rig is developed and presented in this paper. The setup consists of a single-stage centrifugal compressor with a shrouded impeller providing a pressure ratio up to 1.85. On the pressure side, the diffuser is followed by a volute and a throttle to capture the whole speed characteristic between surge and choke. Thermodynamic data, such as pressure and temperature upstream and downstream of the compressor, are recorded as well as torque and rotational speed at the shaft coupling. In addition, the test rig can also be used to investigate the effects of wet compression. For this purpose, a spray nozzle can be installed in front of the impeller’s bell mouth. In order to investigate the influence of temperatures on evaporation rates, a preheater in front of the compressor section is installed to heat the air up to temperatures of 80 °C. In this paper, dry results are shown for inlet temperatures of 22, 30, 40 and 50 °C. To compare the characteristics at different preheated conditions, reduced rotational speed and air mass flow rate are kept constant. These resulting performance maps are in good agreement between each case. The numerical results of Part A are validated by the experimental data herein.