Supersonic shear layer characteristics of two fluids with a splitter plate

Supersonic shear layer development affects mixing between the primary and secondary fluids in a supersonic ejector substantially. The splitter plate plays a key role in shear layer development in the near-trailing-edge region. In this paper, supersonic shear layers with various splitter plate thicknesses are calculated and analyzed. Two types of instability modes are found when various splitter plate thicknesses are used. The shock wave strength and absolute unstable region determine the instability modes. Shock waves can limit instability development but an absolute unstable region promotes instability development. Velocity thickness growth rates are found to be the result of the merging process between two or more adjacent vortices in the transition region. The number of vortices that merge depends on the ratio of the vortex shedding and nature frequencies. The velocity thickness growth rates are larger under the local instability mode than under the global instability mode since three vortices merge under the former mode but two vortices merge under the latter. This study may provide a helpful reference for the design of supersonic ejectors. •Two types of instability modes are found when various splitter plate thicknesses are used.•The shock wave strength and absolute unstable region are proved to be the determining factors for instability modes.•Velocity thickness growth rates are the result of merging process between two or more adjacent vortices.