INSIGHT INTO THE FLOW CHARACTERISTICS DOWNSTREAM OF MICRO VORTEX GENERATORS

Date

2023-9-08

Author

Akpolat, Muhiddin Tuğrul

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This study investigates the wake characteristics of Micro Vortex Generators (MVGs) in a subsonic flow regime. First, the wakes generated by three ramp-type MVGs with different height-to-boundary layer thickness ratios (h/δ) are characterized experimentally using a two-dimensional two-component particle image velocimetry technique. The experimental results are complemented with three-dimensional numerical simulations for five different h/δ ratios ranging from 0.18 to 0.54. The effect of the device height, or the h/δ ratio, is investigated in terms of velocity components, vorticity distributions, turbulence properties, and various decay parameters, such as maximum streamwise velocity deficit and maximum upwash velocity, using five different device heights employing the experimental and numerical results. The self-similarity of the ramp-type MVG wake in terms of streamwise and wall-normal velocity components is investigated. The wake flow properties are then compared to similar types of MVGs operating in the supersonic regime available from the literature. The experimental and numerical results reveal general operating principles and wake decay characteristics in the low subsonic flow regime, which display similar characteristics to MVGs of similar h/δ values operating at supersonic conditions. It is shown that the vortex strength, and thus mixing and wake decay characteristics, depend on the effective device Reynolds number regardless of the Mach number. A wake model is suggested by using the self-similarity of the ramp-type MVGs and the wake decay parameters. Using the detailed investigation of the decay parameters for the modeling efforts, a method to designate the limit between MVGs and conventional (δ-scale) vortex generators is suggested based on the wake deficit decay characteristics. The model is then used to reconstruct wakes of ramp-type MVGs in supersonic flow regimes from the literature.

Subject Keywords

Micro Vortex Generators, Flow Control, Experimental Aerodynamics, Computational Fluid Dynamics

URI

https://hdl.handle.net/11511/105371

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Graduate School of Natural and Applied Sciences, Thesis