A computational study of direct simulation of high speed mixing layers without and with chemical heat release

Sekar, Balu; Mukunda, H. S.

doi:10.1016/s0082-0784(06)80320-6

Cited by 18 publications

(12 citation statements)

References 3 publications

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“…The code used in the present calculations is the SPARK2D combustion code developed at the NASA LaRC by Drummond and Carpenter 4 and has already been used in Sekar and Mukunda 6 and Mukunda. 21 It uses a 4th order compact MacCormack scheme with second order temporal accuracy.…”

Section: The Code and Computational Detailsmentioning

confidence: 99%

“…Supersonic reacting flows have been explored experimentally [1][2][3] and computationally [4][5][6][7] and in the recent times on the modeling aspects. [8][9][10] Two experimental studies which have been explored computationally are the experiments of Burrows and Kurkov 1 and of Evans et al 11 In the former case, H 2 comes off as a wall-jet with the free stream consisting of high temperature vitiated air.…”

Section: Introductionmentioning

confidence: 99%

“…Exploration of the thermo-fluid behavior on supersonic mixing layers has been made by Sekar and Mukunda 6 and Vuillermoz et al, 7 modeling aspects have been treated by Zheng and Bray, [8][9][10] and a summary of these aspects is available in Bray. 10…”

Section: Introductionmentioning

confidence: 99%

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A thermo-chemical exploration of a two-dimensional reacting supersonic mixing layer

et al. 1997

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The hypervelocity two-dimensional reacting supersonic mixing layer experiments of Erdos et al. with a H 2 /air stream have been simulated with model free fine grid calculations on a N-S solver with full and single step chemistry. Response of the flow to fluctuations in the inflow stream is utilized to examine chemistry fluid flow interactions. A favourable comparison of the computation with experimentally measured wall static pressure and heat transfer data along with flow picture forms the basis for further analysis. Insight into the mean flow thermal and reaction properties is provided from the examination of large scale structures in the flow in which the hydrogen stream is at 103 K flowing at 2.4 km/s (M ϭ3.09) and the air stream is at 2400 K flowing at 3.8 km/s (M ϭ3.99). The chemistry-flow interaction is dominated by large stream kinetic energy and affects the mean properties including the temperature profiles across the mixing layer. Single step chemistry, in comparison to full chemistry, is inadequate to describe ignition and early combustion processes, but seems reasonable for describing mixing and combustion downstream. Fast chemistry approximation coupled with mixture fraction based on hydrogen element seems to predict H 2 mean profiles well; but this is shown to be due to the insensitivity of Y H 2 to progress of the reaction. This approximation under-predicts Y O 2 though the general shape of the profile is maintained. Mixture fraction variable approach is shown to be inadequate for the prediction of the H 2 O mass fraction because of the effect of non-normal diffusion. Finite chemistry conditions are shown to prevail throughout the domain of the mixing layer. It appears that use of mixture fraction approach may be inadequate to compute high speed reacting turbulent flows.

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Section: The Code and Computational Detailsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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A thermo-chemical exploration of a two-dimensional reacting supersonic mixing layer

et al. 1997

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“…al. 24 In their study of chemically reacting mixing layers, they compared the performance of various combustion models. In particular they found that the resu lts obtained with a 7-species, 7-step reaction mechanism, very similar to the one used in the present study, were nearly identical to t hose obtained with a more complete 9-species, 18-step model at various inflow conditions.…”

Section: Combustion and Turbulence Modelmentioning

confidence: 99%

Numerical study of shock-wave/boundary layer interactions in premixed hydrogen-air hypersonic flows

Yungster

1991

29th Aerospace Sciences Meeting

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A computational study of shock wave/boundary layer interactions involving premixed combustible gases, and the resulting combustion processes is presented. The analysis is carried out using a new fully implicit, total variation diminishing (TVD) code developed for solving the fully coupled Reynolds-averaged Navier-Stokes equations and species continuity equations in an efficient manner. To accelerate the convergence of the basic iterative procedure, this code is combined with vector extrapolation methods. The chemical nonequilibrium processes are simulated by means of a finite-rate chemistry model for hydrogen-air combustion. Several validation test cases are presented and the results compared with experimental data or with other computational results. The code is then applied to study shock wave/boundary layer interactions in a ram accelerator configuration. Results indicate a new combustion mechanism in which a shock wave induces combustion in the boundary layer, which then propagates outwards and downstream. At higher Mach numbers, spontaneous ignition in part of the boundary layer is observed, which eventually extends along the entire boundary layer at still higher values of the Mach number.

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“…Most of the previous works, which have studied the entrainment process in reacting turbulent shear flows, have focused on the effect of heat release on the overall growth rate of the shear layer (Hermanson & Dimotakis 1989;McMurtry et al 1989;Sekar & Mukunda 1991;Miller et al 1995;Livescu et al 2002;Pantano et al 2003;Mahle et al 2007;Mathew et al 2008;OBrien et al 2014). While all of these works have reported a reduction in growth rate due to the effects of heat release, none have quantified the mass that enters the shear layer.…”

Section: Introductionmentioning

confidence: 99%

The effect of heat release on the entrainment in a turbulent mixing layer

Jahanbakhshi

Madnia

2018

J. Fluid Mech.

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Direct numerical simulations of a temporally evolving compressible reacting mixing layer have been performed to study the entrainment of the irrotational flow into the turbulent region across the turbulent/non-turbulent interface (TNTI). In order to study the effects of heat release and interaction of the flame with the TNTI on turbulence several cases with different heat release levels, $Q$, and stoichiometric mixture fractions are chosen for the simulations with the highest opted value for $Q$ corresponding to hydrogen combustion in air. The combustion is mimicked by a one-step irreversible global reaction, and infinitely fast chemistry approximation is used to compute the species mass fractions. Entrainment is studied via two mechanisms: nibbling, considered as the vorticity transport across the TNTI, and engulfment, the drawing of the pockets of the outside irrotational fluid into the turbulent region. As the level of heat release increases, the total entrained mass flow rate into the mixing layer decreases. In a reacting mixing layer by increasing the heat release rate, the mass flow rate due to nibbling is shown to decrease mostly due to a reduction of the local entrainment velocity, while the surface area of the TNTI does not change significantly. It is also observed that nibbling is a viscous dominated mechanism in non-reacting flows, whereas it is mostly carried out by inviscid terms in reacting flows with high level of heat release. The contribution of the engulfment to entrainment is small for the non-reacting mixing layers, while mass flow rate due to engulfment can constitute close to 40 % of the total entrainment in reacting cases. This increase is primarily related to a decrease of entrained mass flow rate due to nibbling, while the entrained mass flow rate due to engulfment does not change significantly in reacting cases. It is shown that the total entrained mass flow rate in reacting and non-reacting compressible mixing layers can be estimated from an expression containing the convective Mach number and the density change due to heat release.

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A computational study of direct simulation of high speed mixing layers without and with chemical heat release

Cited by 18 publications

References 3 publications

A thermo-chemical exploration of a two-dimensional reacting supersonic mixing layer

A thermo-chemical exploration of a two-dimensional reacting supersonic mixing layer

Numerical study of shock-wave/boundary layer interactions in premixed hydrogen-air hypersonic flows

The effect of heat release on the entrainment in a turbulent mixing layer

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