Passive control of pressure fluctuations generated by separated flow

摘要

Measurements of wall-pressure fluctuations have been made in the flow behind a backward-facing step, with a permeable reattachment surface. Different configurations are tried, the most successful producing a reduction in peak rms pressure fluctuation of about 13 and a reduction in drag of about 9. Spectra show that most of the attenuation occurs at low frequencies, and in particular, the "flapping" frequency (n approximate to 0.1) is effectively removed. The main reason for this appears to be that the permeable surface inhibits the upstream convection of disturbances produced at reattachment. Structural modifications to the pressure-fluctuation field appear to be confined to the region upstream of mean reattachment. References: 25