Radial profile of moments of instantaneous axial velocity of a fully pulsed axisymmetric jet

Radial distribution of the first and higher moments of instantaneous axial velocity of a fully pulsed round jet were investigated along 80 diameters downstream from the jet exit. Response of the unsteady flow to the varying Reynolds and Strouhal numbers thus allowing a series of distinct pulses were sampled using a single wire hot-wire anemometer. It was found that the first moments, as compared to steady jet phenomena, do not maintain self-similarities over the flow domain but their shapes remain unchanged. At a lower Reynolds and Strouhal number, widening radial profiles of the first moment are obtained. Transverse profiles of the third and fourth turbulence moments explain the nature of random process in the mechanically excited jet. Their values were found to remarkably depart from the Gaussian values and to be significantly higher than those of the steady jet across the observed jet widths hence yielding more intense-highly irregular motions and more spreading jet. For all the tested cases, it was demonstrated that the direct effects of the controlled parameters on the flow field become stronger in the outer region than in the inner conterpart of the jet width.