Reynolds Number Effects in Cascades and Axial Flow Compressors

Abstract

A series of tests on guide vane and compressor cascades is reported. The Reynolds number was varied in the guide vane cascade tests, and the Reynolds number and the cascade aspect ratio were varied in the compressor cascade tests. The substantial laminar separation observed in the compressor cascades at high aspect ratio (and low Reynolds number) was suppressed in the cascade tests at low aspect ratio, 2:1. Effects of Reynolds number variation on the performance of a single stage axial flow compressor are also given, and compared with predictions of performance using the cascade tests. Calculations of laminar separation points agree quite well with the experimental observations. It appears that transition due to laminar boundary layer instability is unlikely to occur on compressor blades, in the normal operating range of Reynolds number.

Effect of Reynolds Number on Separation Bubbles on Controlled-Diffusion Compressor Blades in Cascade

“…The separation region had moved forward with a. decreasing Reynolds number and the separation bubble had also affected the minimum suction peak by reducing its magnitude. Both these observations were consistent with earlier separation bubble studies as reported by Rhoden (1965), Horlock et. al.…”

“…The design-point Reynolds number, based on chord, for stator 67B was almost one million at sea level, and this was estimated to decrease to 200,000 at 15,000 m. Three Reynolds numbers (namely 640,000, 380,000 and 210,000) were tested with ten • stator 6M blades in cascade in the Naval Postgraduate School, Low-Speed Cascade Wind Tunnel. Many earlier cascade wind tunnel tests have been conducted to study the effect of Reynolds number on blade element performance, most notably those by Rhoden (1956), Horlock et. al.…”

Utilization of Cascade Data in Axial-Flow Compressor Design and Analysis: A Critical Review

“…Some selected examples are briefly outlined in the following paragraphs to illustrate the pattern of current (17). Cascade Reynolds number work has been carried out at length in several laboratories (37,38), Miniaturization of axial-flow compressors for space and vehicular gas turbine units has increased the need for valid methods of estimating the effects of low Reynolds number. It is interactivity.…”