Turbulence Measurements in Axisymmetric Jets of Air and Helium

Download or read book Turbulence Measurements in Axisymmetric Jets of Air and Helium written by N. R. Panchapakesan and published by . This book was released on 1991 with total page 226 pages. Available in PDF, EPUB and Kindle. Book excerpt: A turbulent round jet of air discharging into quiescent air was studied experimentally. X-wire hot-wire probes mounted on a moving shuttle were used to eliminate rectification errors due to flow reversals in the intermittent region of the jet. Moments of velocity fluctuatuions up to fourth order were measured to characterize turbulent transport in the jet and to evaluate current models for triple moments that occur in the Reynolds stress equations. Fourth moments were very well described in terms of second moments by the quasi-gaussian approximation across the entire jet including the intermittent region. Profiles of third moments were found to be significantly different from earlier measurements. The Basic triple moment model that inlcluded turbulent production and models for the dissipations and the return to isotropy part of the pressure correlations was found to be unsatisfactory. When mean-strain production and a model for rapid pressure correlations were also included, predictions were satisfactory in the fully turbulent region.