DNS of transition to turbulence in a linear compressor cascade

A series of direct numerical simulations were carried out of the flow through a compressor passage. The behavior of the flow in the presence and absence of free-stream turbulent fluctuations is contrasted. In the former case, both the pressure and suction surface undergo separation due to the adverse pressure gradient in the passage. In the presence of free-stream turbulent fluctuation, the pressure surface boundary layer transitions to turbulence upstream of the laminar separation point and, hence, remains attached. The suction surface, however, undergoes separation independent of the free-stream perturbation. The frequency of shedding, however, and the mechanics of the separation region, are dependent on the turbulence level in the free-stream. Further simulations at higher turbulence intensities are planned.