Application of a Multistage Casing Treatment in a High Speed Axial Compressor Test Rig

Abstract

The subject of this paper is the experimental investigation of the overall performance and local aerodynamics of a 2.5 stage axial compressor test rig with a two stage casing treatment. Casing treatments are a well known method to aerodynamically stabilize the near stall compressor aerodynamics. However, in the past, casing treatments have only been applied to high aspect ratio front stages. This investigation puts the focus on the impact of advanced casing treatments applied to both rotors of a high speed compressor test rig. The rotors’ geometric and aerodynamic features are identical to those seen in the rear stages of aircraft engine high pressure compressors. Based on experimental results, we explain the casing treatment’s effect on the local flow phenomena as well as its influence on the compressor operability and performance. In order to clearly quantify the casing treatment’s influence, all measurements are conducted twice: for the rig without casing treatments and for an identical rig with casing treatments. The analysis of experimental data confirms that multistage casing treatments are able to significantly push the surge line towards higher pressure ratios and lower mass flow rates without any significant degradation of the peak efficiency. However, detailed flow analysis and the comparison of the configurations with and without casing treatments reveal that the flow is significantly redistributed by the effect of the casing. The present effort was conducted as part of the EU integrated program for New Aero Engine Core Concepts (NEWAC).