Turbulent boundary-layer modification by streamlined devices
Unsteady aerodynamic theory and the rapid distortion approximation are used to study the modification of turbulent boundary-layer large-eddy structure by streamlined devices. In response to the fluctuations in the flow, the streamlined device will shed vorticity which induces a velocity field that modifies the turbulent boundary layer structure. The fluctuating velocity downstream of thin plate and airfoil-shaped devices is calculated throughout the boundary layer for subsonic flows with two-dimensional and three-dimensional upstream harmonic disturbances. The results show that such devices most effectively suppress the fluctuating vertical velocity for a range of streamwise reduced frequencies. The intensity and the range of maximum suppression depends on the device geometry, loading, its distance to the wall, as well as the upstream disturbance conditions and the Mach number of the flow. It is shown that there is a significant effect of the wall, and it should be included in the analysis. The results also show that the modifications of the boundary layer are more significant if two devices are used, and if the devices have different chord lengths, and wider range of disturbances can be suppressed.
- Research Organization:
- Notre Dame Univ., IN (USA)
- OSTI ID:
- 5293834
- Country of Publication:
- United States
- Language:
- English
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