Modelling of high-enthalpy, high-Mach number flows

Abstract

A review is made of the computational models of high-enthalpy flows developed over the past few years at the von Karman Institute and Université Libre de Bruxelles, for the modelling of high-enthalpy hypersonic (re-)entry flows. Both flows in local thermo-chemical equilibrium (LTE) and flows in thermo-chemical non-equilibrium (TCNEQ) are considered. First, the physico-chemical models are described, i.e. the set of conservation laws, the thermodynamics, transport phenomena and chemical kinetics models. Particular attention is given to the correct modelling of elemental (LTE flows) and species (chemical non-equilibrium—CNEQ—flows) transport. The numerical algorithm, based on a state-of-the-art finite volume discretization, is then briefly described. Finally, selected examples are included to illustrate the capabilities of the developed solver.

Multi-fluid Modeling of Magnetosonic Wave Propagation in the Solar Chromosphere: Effects of Impact Ionization and Radiative Recombination

“…The latter is an open-source platform for high-performance scientific computing 3 featuring advanced computational models/ solvers for tackling re-entry aerothermodynamics (Degrez et al 2009;Lani et al 2013a;Munafo et al 2013;Garicano Mena et al 2015), simulation of experiments in highenthalpy facilities (Knight et al 2012;Zhang et al 2016), ideal magnetohydrodynamics for space weather prediction (Yalim et al 2011;Lani et al 2014), radiation transport by means of ray tracingand Monte Carlo (Santos & Lani 2016) algorithms, etc.…”

Novel Method to Calculate Vibrational Thermal Conduction in Hypersonic Nonequilibrium Flow

“…The vibrational thermal conduction of the mixture can be easily calculated from Eq. (17). However, when the two-temperature model is used, there is only one vibrational energy equation for the vibrational energy of the mixture e vib , and the directly solved variable is e vib rather than the species vibrational energy e vib;s .…”

“…A number of aerothermodynamic codes have adopted the model, including the LAURA code developed by Gnoffo [13] and Cheatwood and Gnoffo [14], the GASP code [15,16], and the computational models and solver for high-enthalpy flows developed at the von Kármán Institute and Universite Libre de Bruxelles [17]. Using this model, Keenan and Candler [18] studied the reentry flowfield over sphere-cone geometries with thermochemical ablation of graphite heat shield; Kaneko et al [19] simulated the flowfield of a nozzle starting process with thermal and chemical nonequilibrium in a high-enthalpy shock tunnel; and MacLean et al [20] studied the thermochemical modeling of the flows over a two-dimensional cylinder and a double cone in the reflected shock tunnel facility at high enthalpy.…”

Multitemperature Dissociation Rate of N2+N2→N2+N+N Calculated Using Selective Sampling Quasi-Classical Trajectory Analysis

“…To incorporate these effects, a reliable description of thermal nonequilibrium is needed in the CFD approach. Here, many models are available [4][5][6][7][8][9][10][11]17,21,23,[27][28][29][30][31][32]. The most comprehensive description will require the solution of a transport equation for the population of molecules in each rovibrational state, which is the equivalent of a spatially inhomogeneous master equation [15,17,[33][34][35].…”

“…For N 2 -O 2 systems under this description, an additional O10 4 transport equations would need to be solved alongside the CFD simulation (one for each rovibrational state), making full-scale simulations intractable. In most practical applications, a state-averaged approach is used [7][8][9]16,23,29,30,40], which invokes a multitemperature description. Here, each internal mode (i.e., vibrations, rotations, and translations) are individually assumed to be at equilibrium, but at different temperatures, leading to mode-specific temperatures denoted as vibrational (T v ), rotational (T r ), and translational (T t ) temperatures.…”