High Speed Testing and Numerical Validation of an Aggressive Intermediate Compressor Duct

Abstract

An experimental and numerical investigation of the flow in an s-shaped compressor duct is presented in this paper. The experimental test was conducted in the compressor test facility at STARCS in Bromma, Sweden. The duct was designed based on geometrical properties of corresponding low-speed tests performed at the Universities of Cambridge and Loughborough in the UK in the EU research project AIDA. For the high-speed test, the geometry was scaled to fit the downstream compressor, keeping the non-dimensional characteristics of the duct as similar to the low-speed configurations as possible. Extensive CFD calculations were performed to assist the set-up of the test and to predict the duct performance in detail. The duct was equipped with static pressure taps on hub and shroud as well as on the strut. The duct inlet and exit flowfields were scanned using a miniature five-hole pressure probe that provided total pressure, velocities and flow angles. Two different duct surface finishes were tested at two different compressor operational points. Using the five-hole probe results, the duct loss could be estimated and compared to that of the CFD. For the CFD analysis a surface roughness model was used to account for the different surface finishes of the duct. The results show that using the surface roughness model makes it possible to account for the increase in loss due to a rougher flow surface. The absolute loss values are however under-predicted by approximately 10% in the CFD compared to the experiments.