A gas turbine engine in which the angle of the
inlet guide vanes can be changed to meet the requirements of the engine-operating conditions. These are normally in front of the first stage of an axial compressor and sometimes in the subsequent stages as well. Normally, they are closed during engine starting and low RPM, but they open progressively as the RPM is increased. At low RPM, the angle of attack of the low-pressure blades is kept moderate to avoid stalling. Variable-
inlet guide vanes are not common in front of the turbine. See
inlet guide vanes.