Experimental and Numerical Investigation of the Flow in a 5-Stage Transonic Compressor Rig

Abstract

The flow in a 5-stage transonic compressor rig was experimentally and numerically investigated. The rig is geometrically scaled from the front part of an existing heavy duty gas turbine compressor with CDA-blading. At several operating points pressures and temperatures were measured in order to get the performance map of the compressor, radial distributions at vane leading edges and static pressures at vanes and casing. In order to identify shock locations and to get information about the rotor-stator interactions and the flow angles, 3D L2F-measurements were done in the first and second rotor at two speeds. A newly developed double periodic measuring L2F-system was employed in order to analyze the results with respect to up- and downstream effects of both rotors. The experimental data were used for the validation and calibration of two steady 3D multistage Navier-Stokes codes with mixing plane models between the blade rows. With STAGE3D, calculations were mainly done for the first 2 transonic stages in order to compare shock locations, velocities, inlet and outlet flow angles with measurements. Furthermore the code was calibrated, which means, that grid sizes and numerical parameters were adjusted to give the best fit to the experiments while having acceptable calculation times. A set of parameters was found, which will be used for the design of new transonic multistage compressors. However not all flow quantities fit well to the measurements. Mass flow and pressures could not be fulfilled at the same time. The other code used was TRACE-S. A procedure for a fast calculation of the whole performance map for all 9 blade rows together was developed and tested. The shape of the calculated speed lines fit well to the measured ones, but the mass flow is predicted too high at off-design conditions. The reason is a too low calculated loss production which is confirmed by the higher calculated radial total pressure distributions.