Inlet Guide Vanes (IGVs) are used to deliver a defined preswirl for the following rotor and can be used to adjust the stage’s aerodynamic performance. Using Variable Inlet Guide Vanes (VIGVs) the preswirl can be varied in a wide range in order to control the compressor’s operating point. Figure 1 shows a VIGV as applied in multishaft compressors. These machines are used for compression of gases in several industrial fields like fertilizer industry, oil and gas or power generation ([12], [13]). They provide a pressure ratio up to 150 and in most applications they run with a constant shaft speed. Hence, these compressors are adjusted basically by VIGVs (see [3]). Vanes with symmetric profiles are often found as their stagger angle can be changed in both positive and negative direction without preference of one of the turning directions. Disadvantages of symmetric VIGVs are high losses at relatively small turning angles and eventually a high sensitivity for stall occurrence ([5], [9]). In order to reduce the losses and to optimize the blade performance, it is essential to know details of the flow on the vane (e.g. the presence of a laminar or turbulent boundary layer, flow separation, transition etc.). Experimental investigations with a VIGV linear cascade have been conducted at the Institute of Jet Propulsion at the Universität der Bundeswehr München. The effects of varying stagger angle and Reynolds number on the profile losses are investigated and the detailed analysis is supported by measurements inside the boundary layers on the vane surface. For this reason a Preston probe was used to determine the near wall flow and to perform traverses along the boundary layer.    «

Inlet Guide Vanes (IGVs) are used to deliver a defined preswirl for the following rotor and can be used to adjust the stage’s aerodynamic performance. Using Variable Inlet Guide Vanes (VIGVs) the preswirl can be varied in a wide range in order to control the compressor’s operating point. Figure 1 shows a VIGV as applied in multishaft compressors. These machines are used for compression of gases in several industrial fields like fertilizer industry, oil and gas or power genera...    »