Direct numerical simulation of an isothermal reacting turbulent wall-jet
2011 (English)In: Physics of fluids, ISSN 1070-6631, E-ISSN 1089-7666, Vol. 23, no 8, 085104- p.Article in journal (Refereed) Published
In the present investigation, Direct Numerical Simulation (DNS) is used to study a binary irreversible and isothermal reaction in a plane turbulent wall-jet. The flow is compressible and a single-step global reaction between an oxidizer and a fuel species is solved. The inlet based Reynolds, Schmidt, and Mach numbers of the wall-jet are Re = 2000, Sc = 0.72, and M = 0.5, respectively, and a constant coflow velocity is applied above the jet. At the inlet, fuel and oxidizer enter the domain separately in a non-premixed manner. The turbulent structures of the velocity field show the common streaky patterns near the wall, while a somewhat patchy or spotty pattern is observed for the scalars and the reaction rate fluctuations in the near-wall region. The reaction mainly occurs in the upper shear layer in thin highly convoluted reaction zones, but it also takes place close to the wall. Analysis of turbulence and reaction statistics confirms the observations in the instantaneous snapshots, regarding the intermittent character of the reaction rate near the wall. A detailed study of the probability density functions of the reacting scalars and comparison to that of the passive scalar throughout the domain reveals the significance of the reaction influence as well as the wall effects on the scalar distributions. The higher order moments of both the velocities and the scalar concentrations are analyzed and show a satisfactory agreement with experiments. The simulations show that the reaction can both enhance and reduce the dissipation of fuel scalar, since there are two competing effects; on the one hand, the reaction causes sharper scalar gradients and thus a higher dissipation rate, on the other hand, the reaction consumes the fuel scalar thereby reducing the scalar dissipation.
Place, publisher, year, edition, pages
2011. Vol. 23, no 8, 085104- p.
boundary layer turbulence, chemically reactive flow, compressible flow, flow simulation, fluctuations, jets, Mach number, numerical analysis, pattern formation, shear turbulence, subsonic flow
Other Materials Engineering
IdentifiersURN: urn:nbn:se:kth:diva-39188DOI: 10.1063/1.3622774ISI: 000294483500032ScopusID: 2-s2.0-80052338449OAI: oai:DiVA.org:kth-39188DiVA: diva2:439518
FunderSwedish Research Council, 621-2007-4232
QC 201109082011-09-082011-09-082015-02-25Bibliographically approved