I have a centrifugal impeller that I am simulating using a rotating region. Because the estmiated blade tip Mach number is greater than 0.3 I am solving using compressible flow. The working fluid is air. I have set the air volumes' material to allow the density to vary according to the ideal-gas euqation of state.
Problem: Within the rotating region the air static temperature is LOWER than the surrounding environment. This is physically unrealistic, since the temperature of a gas increases when it is compressed. As can be seen from the attached image, the temperature change is immediate upon transition from the inlet air volume to the rotating region.
Is there something I am missing about running a rotating region analysis with compressible flow?