CFD Simulations of the TP400 IPC With Enhanced Casing Treatment in Off-Design Operating Conditions

The TP400 intermediate pressure compressor (see Figure 1) is characterized by its extremely wide aerodynamic operating range with strong requirements concerning efficiency and surge margin. Both goals could have been achieved by the proper introduction of variable stator vanes. However, the resulting weight penalty due to the necessary control and actuator system is not accepted — thus this conventional design is rejected and a sophisticated Casing Treatment developed by MTU is introduced. While the underlying multipoint design process is in general expensive and complex the chosen Casing Treatment design (enhanced axial skewed slots [17]) requires the introduction of time accurate 3D CFD simulations in the standard design chain. This ambitious goal leads to the demand for enhanced 3D aerodynamic design tool capabilities like accurate flow prediction in fully turbulent and transitional flow regimes due to different operating conditions as well as the resolution of different geometry features outside the main flow path. In the present paper the effect of different numerical resolution of the “real” geometry as well as the “real” behavior of the flow e.g. steady simulation versus time accurate simulations is discussed. The differences are analyzed and compared to rig-measurements.Copyright © 2009 by ASME