Combination interaction of Taylor–Goertler vortices in a curved shear layer of a supersonic jet

Abstract

-Web page: http://www.itam.nsc.ru/ The importance of the study of the turbulent mixing processes in a shear layer of the supersonic jet is caused by an extensive use of jets in practice. The brief review of experimental research of an origin formation and development of streamwise vortex structures in a mixing layer of a supersonic jet is presented. It has been experimentally established that the initial section of the shear layer of a supersonic nonisobaric jet exhausting from an axisymmetric nozzle has a three-dimensional structure. The presence of these vortex structures is interpreted as a three-dimensional structure of the turbulent flow [1,2]. Main goal of this paper consist in a finding of the conditions for control of the process of the generation streamwise vortex structures in the supersonic jet shear layer. Results of measurement of distribution of Pitot pressure in supersonic nonisobaric jet both in radial and in azimuthal directions are submitted. Azimuthal heterogeneity, corresponding to streamwise vortices in a shear layer, is analyzed with use as Fourier analysis and with application of wavelet analysis. Influence of the shear layer curvature on development process of streamwise vortices is discussed in [3]. For more carefully investigation of this question it was selected two jets with identical gasdynamic parameters but with different curvatures in initial section of the jet shear layer. Supersonic jets were issued from the convergent nozzle (Ma=1.0) and convergent-divergent Laval nozzle (Ma=2.0). Both nozzles were manufactured with polished inner surfaces. Jets were issued to the embient ambient air. The radius of the nozzle exit was equal R a =15 mm. The experiments have been performed in the special jet insert for hypersonic aerodynamic wind tunnel T-326 of ITAM SB RAS with cold air. Experimental data were obtained for nozzle pressure ratio Npr=Po/Pc=5.0 (here Po is stagnation pressure, Pc -ambient pressure in test chamber). Results of the turbulent flow visualization and jets schemes are presented in Fig.1.

Free underexpanded jets in a quiescent medium: A review

“…Thus, the only papers providing quantitative results for the length of the potential core [30,156] [30,65,59,135,[157][158][159][160][161][162][163][164][165][166][167][168][169][170][171][172][173][174]149,122,61,94] yet some numerical papers are also available [37,59,122,[175][176][177][178][179][180][181]. These structures play a major and significant role in the behavior of the jet, especially in its spreading rate and the associated decay, because of their interaction with the various shock waves [134,38,158,156,164,52,149,178,166,171]<...>…”

“…Furthermore, the counter-rotating vortices modify the azimuthal distributions of the characteristic variables, which appear to have a petal-like structure. Hence, one may observe local maxima and minima exhibiting sinuous type variation, whose spatially modulated magnitude increases with the distance from the exit plane as the eddies grow in size [30,157,65,152,167,94,171,174,181]. Apparently, the maxima of density and of convective speed coincide together [184].…”

Identification of Instability Modes of Transition in Underexpanded Jets

“…Even though many previous studies have made some measurement of turbulence-using, for instance, hotwire anemometry 9,10 -very few studies of supersonic free jets discuss turbulent flow structures. Notable exceptions include the free-jet studies of streamwise vortices in the outer shear layer of underexpanded jets by Krothapalli et al 11 and Zapryagaev et al 12 Krothapalli et al successfully visualized cross-sectional slices through the flow using Mie scattering off of moisture in the ambient air that condensed when mixed with the cold fluid of the jet. In the study by Zapryagaev et al, the presence of these vortical flow structures was inferred from Fourier spectral analysis of pitot pressure surveys, being the most likely explanation for the measured azimuthal pressure variations.…”

“…Peters and Phares 18 report on such jets with a turbulent mixing layer along the jet boundary of the 9 barrel shock. Krothapalli et al 11 and Zapryagaev et al 12 report streamwise vortices in the curved outer shear layer, which they attribute to a Taylor-Görtler instability, usually associated with flow along curved walls (described in Turbulent Flows, Pope 6 ).…”

Дифференциальные Характеристики Поля Течения Перерасширенной Газовой Струи В Окрестности Кромки Сопла

“…Несмотря на применение идеализированной математической модели (рассматривается невязкое течение совершенного газа), полученные теоретические результаты выдерживают сравнение с экспериментальными данными [1,2] и могут быть использованы для анализа ряда физических свойств сверхзвуковой струи:…”