Effect of a Recirculating Type Casing Treatment on a Highly Loaded Axial Compressor Rotor

Motoyuki Kawase,Aldo Rona

doi:10.3390/ijtpp4010005

Abstract

The tip leakage flow over the blades of an axial compressor rotor adversely affects the axial rotor efficiency and can determine the onset of tip leakage stall. The performance of a new casing treatment concept in the shape of an axisymmetric recirculation channel is explored by steady Reynolds-Averaged Navier–Stokes (RANS) realizable k-ε modelling on the NASA Rotor 37 test case. The modelling exposed a number of attractive features. The casing treatment increased the stall margin at no penalty to the rotor isentropic efficiency over the rotor operating line. A recirculation in the casing channel self-activated and self-adjusted with the rotor loading to provide more passive flow control at higher rotor loading conditions. The nozzle-shaped recirculation channel outflow opposed the tip leakage jet, re-located the casing surface flow interface further downstream, and reduced the rotor blade tip incidence angle. This combination of features makes the new casing treatment particularly attractive for applications to high thrust-to-weight ratio engines, typical of high-performance jet aircraft.

Highlights

IntroductionExtending the envelope of stable operations allows designers to increase the Stall Margin (SM)
Extending the envelope of stable operations allows designers to increase the Stall Margin (SM)between the normal operating line of the compressor and the compressor surge line
The aim of this paper is to explore this by studying the flow a design, if adopted industry-wide, is high

Summary

Introduction

Extending the envelope of stable operations allows designers to increase the Stall Margin (SM). Between the normal operating line of the compressor and the compressor surge line. It allows operating the compressor at a higher pressure ratio without reducing the stall margin, to benefit the engine thermal cycle. There is, a significant amount of research and commercial interest in finding a way of widening the stable operating envelope of axial compressors that avoids introducing any isentropic efficiency penalty and that increases the compressor stage pressure rise. The potential outcome is a compressor capable of a higher stage pressure rise, resulting in a lower engine weight and in a lower engine cross-section.

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Conclusion