Numerical predictions of turbulent underexpanded sonic jets using a pressure-based methodology

Abstract

Abstract:The objective of this work is to model underexpanded turbulent sonic jets. A pressure-based computational fluid dynamics methodology has been employed, incorporating extensions to handle high speed flows. A standard two-equation turbulence model is used, with an optional compressibility correction. Comparison with experimental jet centre-line Mach number showed the correct shock cell wavelength but a too rapid decay. The compressibility correction had no effect on the shock cell decay but increased the potential core length to give better agreement with experiment. Calculations for nozzle pressure ratios up to 30 showed the variation of Mach disc location in good agreement with experiment. For nozzle pressure ratios above 6, unsteady solutions were observed, emanating from the intersection of the Mach disc with the shear layer. Experimental work has identified similar large-scale instabilities; the peak mode of the prediction had a Strouhal number of 0.16, close to experimental values.

Experimental measurement and Reynolds-averaged Navier–Stokes modelling of the near-field structure of multi-phase CO2 jet releases

“…In the case of the under-expanded air-jet calculations reported upon in Section 3.2, this resulted in fully-refined axi-symmetric meshes containing in the region of 130,000 nodes at 5 levels of refinement. Comparing this to previous similar studies, a non-uniform axisymmetric grid was reported to provide grid-independent solutions at a resolution of 126,000 nodes (Birkby and Page, 2001); an adaptive technique, again used on an axisymmetric grid, reported similar success using 30,000 nodes (Bartosiewicz et al, 2002); and a full 3-dimensional model of a supersonic jet in a cross-flow was reported to be grid-independent using 1,544,098 cells (Viti and Schetz, 2005). Hence, the required level of refinement used in the present work appears to agree with that noted by previous authors.…”

Exhaust of Underexpanded Jets from Finite Reservoirs

“…The error in the pressure measurement is less than the symbol size. Ashkenas and Sherman (1966) Fit to low pressure data [30], and the simulations of Birkby and Page (▽) [31], and Irie et al (◇) [17]. All data are for underexpanded jets with constant supply pressure.…”

A robust methodology for RANS simulations of highly underexpanded jets

“…In fact, whereas the standard k-model leads to an overestimation of the spreading rate of the shear layer, this compressibility correction leads to an opposite effect accompanied by an underestimation of the level of the axially decaying oscillations of the physical variables within the potential core. Such tendencies have been recently confirmed by Birkby and Page [19]. AbdolHamid and Wilmoth [20] have attempted to consider some non-equilibrium turbulence effects in addition to the compressibility corrections.…”