The Effect of the Incidence Angle on the Flow Over a Rotating Disk Subjected to Forced Air Streams

The flow over a stationary and a rotating disk subjected to an outer forced air stream was investigated particular with a look to the effect of incidence angle β. The experiments were carried out with an electrically heated disk placed in a wind tunnel. The measurement of the mean and the local convective heat transfer coefficient enabled a clear study of the flow behavior. The incidence angle β was scanned with high resolution over the entire range, and a large number of crossflow and rotational Reynolds numbers were covered. It was found that a well defined transition incidence angle β existed leading to a symmetry breaking of the flow. The resulting mean heat transfer was in agreement with the phenomenological Landau-de Gennes model in case of small rotational Reynolds numbers. In case of large rotational effects, a different type of transition occurred. Based on the experimental and theoretical results, a discussion of the different phenomena due to the involved flow parameters is given in the paper.