The flow in multistage axial flow compressors isparticularly complex in nature because of the proximity ofmoving bladerows, the growth of end-wall boundary layers andthe presence of tip and seal leakages and secondary flow.The problems associated with these phenomena are at theirmost acute in the latter, subsonic stages of the corecompressor, where Reynolds numbers are modest and theblading has low aspect ratio. Indeed, much of theinefficiency of axial stages is believed to be associatedwith the interaction between blading and end-wall flows.The fact that the end-wall flow phenomena result inconditions local to the blade which are quite differentfrom those over the major part of the annulus wasappreciated by many of the earliest workers in the axialturbomachinery field. However, experiments on bladingdesigns aimed specifically at attacking the end-loss havebeen sparse.This thesis includes results from tests of conventionaland end-bent blading in a four-stage, low-speed, axialcompressor, built specifically for the task, at a scalewhere high spatial measurement resolution could be readilyachieved within the flowpath. Two basic design styles areconsidered: a zero a0 stage with DCA aerofoils and alow-reaction controlled-diffusion design with cantileveredstators.The data gives insight into the flow phenomena present in'buried' stages and has resulted in a much clearerunderstanding of the behaviour of end-bent blading. A3D Navier-Stokes solver was calibrated on the twolow-reaction stators and was found to give good agreementwith most aspects of the experimental results. An improveddesign procedure is suggested based on the incorporationof end-bends into the throughflow and iterative use of the3D Navier-Stokes solver.
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