Near-Wall Flow in Turbomachinery Cascades—Results of a German Collaborative Project

David Engelmann,Tobias Schubert,Francesca Di Mare,Jochen Fröhlich,Jordi Ventosa-Molina,Reinhard Niehuis,Björn Koppe,Martin Sinkwitz,Ronald Mailach

doi:10.3390/ijtpp6020009

Abstract

This article provides a summarizing account of the results obtained in the current collaborative work of four research institutes concerning near-wall flow in turbomachinery. Specific questions regarding the influences of boundary layer development on blades and endwalls as well as loss mechanisms due to secondary flow are investigated. These address skewness, periodical distortion, wake interaction and heat transfer, among others. Several test rigs with modifiable configurations are used for the experimental investigations including an axial low speed compressor, an axial high-speed wind tunnel, and an axial low-speed turbine. Approved stationary and time resolving measurements techniques are applied in combination with custom hot-film sensor-arrays. The experiments are complemented by URANS simulations, and one group focusses on turbulence-resolving simulations to elucidate the specific impact of rotation. Juxtaposing and interlacing their results the four groups provide a broad picture of the underlying phenomena, ranging from compressors to turbines, from isothermal to non-adiabatic, and from incompressible to compressible flows.

Highlights

Present goals in the development of turbomachines for flight propulsion are oriented towards a further increase of pressure ratio and efficiency with a simultaneous reduction of the number of blades and stages of compressor and turbine [1]
The first step taken towards the analysis of the secondary flows in the compressor cascade is to assess the effects of the modelling approach
To study the effect of periodic flow perturbation, the conditions of unperturbed T106RUB inflow were compared to two other cases, one with a moderate frequency of perturbation (Sr = 0.43, φ = 2.97) and another one with a high frequency of perturbation (Sr = 1.33, φ = 0.97), whereas Sr was defined with flow quantities at midspan

Summary

Introduction

Present goals in the development of turbomachines for flight propulsion are oriented towards a further increase of pressure ratio and efficiency with a simultaneous reduction of the number of blades and stages of compressor and turbine [1]. For stationary gas turbines used to generate electric power, challenging demands on flexibility and operation under partial load result from the volatile availability of renewable energies [2]. These requirements on both types of systems lead to high aerodynamic loads on the blade rows and to an increase in losses due to secondary flows [3]. The latter occur mainly in regions close to sidewalls and have been the focus of scientific investigations for many years [4,5,6,7,8,9,10].

Methods

Results

Conclusion