Blade Row Interaction in Axial Compressors, Part II: Unsteady Behaviour of Boundary Layer, Pressure Distribution and Excited Pressure Force of Compressor Blades

R. Mailach, K. Vogeler

abstract:

The aim of this two-part lecture is to give a detailed insight into aerodynamic blade row interaction effects in axial compressors. The lecture notes are organised as following:

In part I a literature survey and an introduction into blade row interactions in axial compressors are given. The results presented in this lecture are from the Dresden Low-Speed Research Compressor. This four-stage compressor will shortly be introduced in part I. Subsequently the measurement techniques and the data postprocessing are explained. Following selected results of the flow field measurements between the blade rows are discussed. Furthermore the steady and periodical unsteady flow field within the rotor blade passages at midspan and near rotor blade tip is considered in detail.

In part II important aspects of the influence of the periodical unsteady flow field on the compressor blades will be discussed. The unsteady boundary layer development is mainly influenced by the incoming wakes. Results for a selected blade row and different operating conditions will be presented. The time-resolved profile pressure distributions are strongly affected by the wakes and the potential flow field of the blades. This will be discussed for several rotor and stator blade rows. Subsequently exemplary results concerning the influence of blade row clocking on the unsteady profile pressures will be considered. Finally, the excitation of unsteady blade forces as a result of the blade row interactions will be regarded. At the end of part II a summary of the main results discussed in this two-part lecture is given.

reference:

Von Karman Institute for Fluid Dynamics (VKI), Lecture Series “Advances in Axial Compressor Aerodynamics”, Rhode-Saint-Genèse, Belgium, May 15-18, 2006.