FLOW CONTROL DOWNSTREAM OF A BACKWARD　FACING STEP

摘要

A simple LEBU-like device aimed at controllingrnthe separated flow field behind a backwardrnfacing step, with special attention on itsrnunsteady properties, is described; the devicernadvantage is that it requires very small designrnmodifications and/or complications. Visualizationsrnof the controlled field are presentedrnalong with wall hot-wire measurements.rnThe latter measurements provided informationrnabout both the mean wall quantities (skinrnfriction) and unsteady properties (wall shearrnstress fluctuations); RMS and spectra of thesernfluctuations are presented, showing how therndistribution of fluctuation energy is influencedrnby the presence of the manipulator. In particular,rnspecific positionings of the device allowedrnto reduce wall unsteadinesses. To summarizernthe outcomes of the work, although thernresearch is in its early stages, the results presentedrnhere prove the viability of this way ofrncontrolling separated flows.