Ventilated cavity flow over a backward-facing step

9th International Symposium on Cavitation

Pearce, B.W.^1 ; Brandner, P.A.^1 ; Foster, S.J.^2

Australian Maritime College, University of Tasmania, Launceston

TAS

7250, Australia^1

Incat Crowther, Sydney

NSW

2084, Australia^2

关键词: Backward facing step;    Boundary layer thickness;    Cavitation tunnels;    Momentum thickness;    Natural boundary;    Turbulent boundary layers;    Ventilated cavities;    Ventilation rate;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/656/1/012164/pdf
DOI  :  10.1088/1742-6596/656/1/012164

来源: IOP

【 摘 要 】

Ventilated cavities detaching from a backward facing step (BFS) are investigated for a range of upstream boundary layer thicknesses in a cavitation tunnel. The upstream turbulent boundary layer thickness is varied by artificial thickening of the test section natural boundary layer using an array of transversely injected jets. Momentum thickness Reynolds numbers from 6.6 to 44 x 103were tested giving boundary layer thickness to step height ratios from 1.25 to 3.8. A range of cavity lengths were obtained by variation of the ventilation flow rate for several freestream Reynolds numbers. Cavity length to step height ratios from 20 to 80 were achieved. Cavity length was found to be linearly dependent on ventilation rate and to decrease with increasing boundary layer thickness and/or Reynolds number. This result may have implications in the practical optimization of these flows which occur in applications such as drag reduction on marine hull forms.