Effects of a Large Eddy Breakup Device on the Fluctuating Wall Pressure Field (Data Bank Contribution)

Abstract

Wall pressure spectra and mean velocity profiles were measured with and without a large eddy breakup device (LEBU) located upstream in high Rθ turbulent boundary layers. Changes of the order of 5 percent occurred in the mean wall shear stress. The wall pressure spectra of the manipulated flow did not show the existence of any highly energized coherent structures, but rather moderate changes occurring over broad frequency ranges. Reductions in the wall pressure autospectra occurred at lower frequencies associated with turbulence activity in the outer layer and the outer portion of the log law layer. Increases occurred at higher frequencies associated with the inner portion of the log law layer. The changes in the wall pressure coherence levels were similar, but generally more complex with greater spatial persistence. The changes in both the autospectra and coherence indicate a conversion of energy from lower to higher convective wavenumbers.