Experimental Characterization of Two Low Aspect Ratio Stages With Scaling Effect for Small Core High Speed Axial Compressor

Abstract

Abstract Due to the increase of the overall pressure ratio, forthcoming aircraft engine designs will exhibit smaller core dimensions, compared to the state of the art. For the high-pressure compressor, this imposes the use of blade rows with aspect ratios well below unity. To assess the validity of current design tools for novel designs, two different stages representative of the last stage of a high-pressure axial compressor have been experimentally characterized at the von Karman Institute for Fluid Dynamics. They both share an identical design methodology, same blade count and rotor tip speed but different aspect ratio, yet well below unity. The current paper proposes a comparison between the stages in terms of overall performance and rotor and stator flow fields, at different Reynolds numbers, and for different operating points. The tip-gap influence has also been assessed by comparing scaled and realistic relative tip gap sizes for the low aspect ratio stage. This study aims at providing an identification of the phenomena driving the performance degradation associated with the reduction of the aspect ratio. This description also paves the way for improvement in existing design tools through a better modelling of the critical physics in this design space.