Showing papers by "Christopher K. W. Tam published in 1985"
TL;DR: In this paper, the effect of turbulence in the mixing layer of the jet is simulated by the addition of turbulent eddy-viscosity terms to the momentum equation, and a comparison of the numerical results with experimental data is given to the mean flow profile and the numerical solution.
Abstract: The present investigation is concerned with the development of an analytical model of the quasi-periodic shock-cell structure of an imperfectly expanded supersonic jet. The investigation represents a part of a program to develop a mathematical theory of broadband shock-associated noise of supersonic jets. Tam and Tanna (1982) have suggested that this type of noise is generated by the weak interaction between the quasi-periodic shock cells and the downstream-propagating large turbulence structures in the mixing layer of the jet. In the model developed in this paper, the effect of turbulence in the mixing layer of the jet is simulated by the addition of turbulent eddy-viscosity terms to the momentum equation. Attention is given to the mean-flow profile and the numerical solution, and a comparison of the numerical results with experimental data.
163 citations
TL;DR: In this paper, a mathematical model of tone-excited jets is developed which consists of two major components: a mathematical description of the process by which the intrinsic instability waves of the jet are excited by the upstream tones; and the modeling of the nonlinear interaction between the mean flow of a jet, the excited large-scale instability waves or turbulence structure, and the fine scale turbulence.
71 citations
TL;DR: In this article, the reduction of shock-associated noise in inverted-velocity-profile coannular jets is quantified and explained by conducting extensive optical and acoustic measurements for a suitable range of outer-stream and inner-stream presure-ratio combinations, and by interpreting the measured noise results with the aid of new theoretical models.
21 citations
TL;DR: In this article, an experimental and theoretical investigation of shock-associated noise of inverted-profile coannular jets is described, and it is theoretically established that this sudden change in the shock structure and hence the decrease in shock associated noise would occur when the primary jet flow is just slightly supersonic regardless of the Mach number and temperature of the fan stream.
10 citations
Journal Article•
TL;DR: In this paper, Tanna et al. investigated the generation of noise by the shock-turbulence interaction with shock cells in an inverted-profile coannular jet with nozzle exit velocity aligned with the jet axis.
1 citations