Viscous Effects On The Instability Of An Axisymmetric Jet

Download or read book Viscous Effects on the Instability of an Axisymmetric Jet written by National Aeronautics and Space Adm Nasa and published by Independently Published. This book was released on 2018-10-18 with total page 30 pages. Available in PDF, EPUB and Kindle. Book excerpt: The stability characteristics of a laminar, axisymmetric jet, issuing from fully developed Poiseuille flow, are investigated. The jet preferred frequency, as inferred from surveys of u'-spectra, is found to yield a Strouhal number (St) that depends on the Reynolds number (R); St and R are based on the jet diameter (D) and the average velocity (U sub av) at the jet origin. The value of St increases with increasing R in the range 400 less than approximately R less than approximately 4000, attaining an asymptotic value of about 0.45. Flow visualization confirms that the instability is primarily in a helical mode, as predicted by stability analyses. Analyses do predict a similar St versus R variation in approximately the correct St-range. However, the R-range where this is predicted is lower than that found experimentally. Zaman, K. B. M. Q. and Seiner, J. M. Glenn Research Center; Langley Research Center RTOP 505-62-21