Numerical and Experimental Study on Bleed Impact on Intermediate Compressor Duct Performance

Abstract

In this study, a comparison is done between an in-house experimental test rig at GKN Aerospace and simulations done using an in-house CFD solver at Chalmers University of Technology. The geometry represents an intermediate compressor duct of an aircraft engine. The main focus is on comparing the flow field at different operating conditions. Those conditions are controlled by extracted massflow through a bleed pipe, upstream of the intermediate compressor duct. The work presented in this paper is done using a RANS solver with the Spalart All-maras turbulence model. The CFD simulations compare well with measured data, for the lower bleed fraction, especially in terms of pressure coefficients in the intermediate compressor duct and at downstream locations. There are strong local effects due to instabilities in the bleed pipe for the higher bleed fraction, which caused the fluctuations in the pressure coefficient and resulted in degraded convergence. The difference in the flow field is also visible when comparing the operating points, where stronger total pressure wakes are noticed in the results for the lower bleed case.