Краткое описание

The wall pressure fluctuations in a pipe behind a cylindrical insertion with eccentricity are studied. Sharp increase of the pressure in a finite region immediately downstream of the insertion, as well as the presence of a pronounced pressure maximum upstream of the point of re-attachment of the separated flow are found. The approximate estimates both for the distance from an axisymmetric insertion to the point of maximal pressure and the pressure magnitude at this point are obtained. The study of the wall pressure power spectrum reveals low-frequency maxima. These are the main distinguishing features of the spectrum under investigation compared to the wall pressure fluctuation spectrum in a fully-developed turbulent pipe flow. These maxima are found to be determined by the appropriate large-scale vortices in the regions of separated and reattached flows, and their frequencies are close to the characteristic frequencies of the vortices formation. The study of the effect of the insertion's eccentricity on the wall pressure statistical characteristics shows that the frequency spectrum is more sensitive to the changes in the eccentricity compared to the root-mean-square pressure.