Competing 3D Mechanisms in Compressor Flows

Abstract

Even though three-dimensional design is central to all modern compressor design systems, many of these methods still rely, at the their core on a two-dimensional, sectional, view of blade aerodynamics. This paper argues that this view fundamentally limits design by not correctly considering the way in which pressure gradient transverse to the flow direction affects both separation and loss. The first part of the paper details how 3D blade stacking and the transverse pressure gradient fundamentally alters the behaviour of the corner separations and trailing edge separations. By controlling this design parameter it is possible to switch between the two. The transverse pressure gradient is also shown to be responsible for a substantial increase in profile loss. In the second part this understanding is used to explore the uncertainty of the design space by simultaneously varying pitch-chord ratio and 3D stacking. It is shown that the design space is split in half by two different levels of risk.