A detailed investigation of the three-dimensional flow was carried out in a low-speed rear axial compressor stage with an aspect ratio of 1. Experimental data were obtained for both an inlet velocity profile with thin endwall boundary layer thickness and a distorted inlet velocity profile with a high turbulence intensity level. The distortion was produced by a specially designed screen. The flow mechanism in the rotor and stator blade rows is analyzed for these two velocity profiles at the design flow coefficient.

A detailed investigation of three-dimensional flow was carried out in a low speed axial compressor stage with aspect ratio of 2. Data were obtained over a range of flow coefficient. The origin of large high loss regions in each blade row was found by means of a diffusion factor. The loss coefficient of rotor and stator blade rows was established on the basis of both rotating and stationary pressure probes. The predicted rotor and stator loss coefficient was compared with experiment.

An aerodynamic investigation of the influence of outlet stator part (vaneless diffuser and return channel) surface roughness on aerodynamic performance of a very low flow coefficient centrifugal stage has been carried out. The stage with design inlet flow coefficient 0.007 was tested within the range of stage Mach number Mu2=0.5–1.1. Then the surface quality of outlet stator part was improved and the tests have been repeated. Aerodynamic performance and losses in both vaneless diffuser and return channel with de-swirl vanes were investigated. The values of isentropic head coefficient increased while those of loss coefficient decreased nearly in the whole range of characteristics in the stage with improved surface quality. The detailed pressure recovery in vaneless diffuser in vicinity of design point measured and calculated by the performance prediction method is compared and discussed. The nonsteady flow phenomena were also investigated. The change of dynamic stability limit by improving of surface quality was observed.

No abstract

A detailed investigation of three-dimensional flow was carried out in a low speed rear axial compressor stage with the change of the stator blade row setting. The stator blade stagger change was in the range of (−14) – (23) degree. Measurements were performed by means of both stationary and rotating pressure probes at seven working points. The origin of large regions of separated flow in blade rows at positive incidence angles was analysed with the use of the spanwise diffusion factor distribution. These areas in the rotor and stator rows originated as the diffusion factor exceeded the critial value D = 0.6 within (1/4 – 1/3) of the blade height near one end-wall. The rotating stall in compressor stage arised when large regions of separated flow occured simultaneously in both rotor and stator blade rows.