Statistics of fully turbulent impinging jets

TL;DR

This study uses direct numerical simulations to analyze the statistical properties of fully turbulent impinging jets, examining the effects of Mach number, Reynolds number, and temperature, and evaluating various Reynolds analogies for temperature prediction.

Contribution

It provides new insights into the applicability of different Reynolds analogies and turbulence models for impinging jets based on DNS data.

Findings

Reynolds and Chilton Colburn analogies agree well outside the impinging area.

Generalized Reynolds analogy and Crocco-Busemann relation are unsuitable for temperature estimation.

Linear entropy-density-temperature relation is confirmed for the wall jet.

Abstract

Direct numerical simulations of sub- and supersonic impinging jets with Reynolds numbers of 3300 and 8000 are carried out to analyse their statistical properties. The influence of the parameters Mach number, Reynolds number and ambient temperature on the mean velocity and temperature fields are studied. For the compressible subsonic cold impinging jets into a heated environment, different Reynolds analogies are assesses. It is shown, that the (original) Reynolds analogy as well as the Chilton Colburn analogy are in good agreement with the DNS data outside the impinging area. The generalised Reynolds analogy (GRA) and the Crocco-Busemann relation are not suited for the estimation of the mean temperature field based on the mean velocity field of impinging jets. Furthermore, the prediction of fluctuating temperatures according to the GRA fails. On the contrary, the linear relation between thermodynamic fluctuations of entropy, density and temperature as suggested by Lechner et al. (2001) can be confirmed for the entire wall jet. The turbulent heat flux and Reynolds stress tensor are analysed and brought into coherence with the primary and secondary ring vortices of the wall jet. Budget terms of the Reynolds stress tensor are given as data base for the improvement of turbulence models.