Numerical simulation of axisymmetric turbulent jets

Abstract

The flow in axisymmetric turbulent jets is numerically simulated with the use of a semi-empirical second-order turbulence model including differential transport equations for the normal Reynolds stresses. Calculated results are demonstrated to agree with experimental data.Introduction. The dynamics of a circular turbulent jet, which is the classical problem of experimental, theoretical, and computational fluid dynamics, has been studied in many papers (see [1][2][3][4][5][6][7][8][9][10][11][12][13][14] and the references therein). The flow in circular turbulent jets at significant distances from the sources was studied in experiments [1,8]. The experiments [1] were performed at a Reynolds number Re = U jet D/ν = 10 5 determined on the basis of the jet velocity U jet and nozzle diameter D with x/D = 30-100; the experiments [8] were performed at Re = 1.1 · 10 4 and x/D = 30-160. The experiments [1,8] were performed by different techniques, and the examined jets exhibit differences in a number characteristic parameters. Possibly, this is the reason for different interpretations of the data obtained. Amielh et al. [9] performed experiments to study the flow dynamics in the near field of turbulent jets of gases with different densities (non-self-similar regimes) in a co-flow, and the data obtained were compared with the results [1,8]. Laboratory measurements were performed at Re = 2.1 · 10 4 and x/D = 0-30. Gharbi et al. [10] reported results of numerical simulations of circular turbulent jets obtained by using a model including transport equations for all components of the Reynolds stress tensor and dissipation rate of the turbulent kinetic energy. The calculated results are shown to be consistent with the experimental data [9]. Piquet [11] performed a detailed analysis of data obtained in experimental and theoretical (including numerical) studies of such flows. Ilyushin and Krasinsky [14] performed a numerical study of a free circular turbulent submerged jet by the large eddy simulation (LES) method; the conditions of experiments [12,13] were modeled, the calculated and measured characteristics of turbulence were compared, and the influence of the model constants and parameters of the numerical algorithm on the accuracy of calculations was analyzed.Though various turbulent jet flows have been studied in much detail, some issues have not be addressed. In particular, numerical models of axisymmetric jet flows are not complete. Numerical simulations performed in [10,14] were compared with experimental data in the near field of the jet. Piquet [11] reviewed the results of numerical analyses of the flow under the test conditions [1, 2] performed with the use of several semi-empirical models of turbulence. As far as we are aware, no numerical simulations of the flow in the far field were performed on the basis of the experimental data [8], which are the most complete ones. There is no unified mathematical model that would allow both the near field (x/D 30) and the far field (x/D 30) to be calculated. The present paper is...