Direct Numerical Simulation Of Turbulent Multispecies Channel Flow With Wall Ablation

Abstract

The design of solid rocket motors requires the prediction of changes induced by the ablation process occurring at the nozzle throat. The present study aims at understanding the effects of ablation on the turbulent boundary layer performing direct numerical simulations in a channel flow configuration. An ablation boundary condition for arbitrary chemical composition and pyrolysis scheme is developed and presented in this paper. Then, two DNS of a seven species reacting flow are performed: a) with inert walls; b) with ablated walls. Generated data are compared and analyzed looking at first order statistics. It is shown that the classical law of the wall for velocity and temperature are not appropriate to represent the numerical result. The chemical equilibrium assumption is shown to be valid in the inert case and a wall function consistent with this assumption is in fair agreement with the results.

DNS of a Periodic Channel Flow with Isothermal Ablative Wall

“…3-b) it is clear that the profiles do not collapse for τ s < τ d . This plot also illustrates the significant changes of atomic composition arising inside the ablative wall TBL which explains that contrary to the inert wall case the equilibrium state is not only dependent on the temperature profile when ablation occurs [6]. This is presented in Fig.…”

“…Another simulation led under the same operating conditions but with inert walls will constitute a reference case. Results of the preliminary study [6] have been improved thanks to an ensemble average procedure giving more details on mass/momentum/energy conservations.…”

“…A full description of the boundary condition is given in Ref. [6]. It is based on the mass budget of the species k at the solid surface:…”

Unsteady coupling of Navier–Stokes and radiative heat transfer solvers applied to an anisothermal multicomponent turbulent channel flow

“…Periodic boundary conditions are applied, in the Navier-Stokes solver, in the streamwise ðxÞ and spanwise ðzÞ directions. Moreover, the streamwise flow is enforced by adding a space/time constant source term to the momentum conservation equation, while a volume source term that warms the fluid is added to the energy conservation equation to sustain the bulk temperature, T b ¼ 2000 K, as presented in [6]. Finally, a no-slip isothermal boundary condition is used at the wall with a constant temperature of T w ¼ 1750 K.…”

Multiscale Study of Reactive Dense Fluidized Bed for FCC Regenerator

“…The pressure P ¼ 2 bar is imposed at the outlet of the network corresponding to the pressure of the gas in FCC regenerators. The heterogeneous reactions are taken into account using a dedicated boundary condition where the normal mass flux at the gas-particle interface is computed using the previous kinetics [14]. In order to obtain a stationary solution of the problem, the carbon quantity transported by the particle is assumed to remain constant and the coke mass fraction is chosen equal to 1%.…”