In this paper, the influence of a chemical kinetic model in hypersonic flow past blunt bodies is examined. Slow and fast chemical kinetic models are investigated to identify the reliable model for applications with a wide range of Mach numbers. Solutions from the Gardiner reaction-rate set, the Moss reaction-rate set, the Park rate set of 1993, and the Dunn and Kang reaction rate are compared. High-temperature, equilibrium-constant curve fits proposed by Gupta are also examined. The new Hansen's formulation for the rate controlling temperature for the dissociation reaction is compared with Park's approach. Particular attention has been devoted to backward reaction rates, because the methods of calculation affect the flowfield structure. Sample hypersonic flowfields, typical of spacecraft reentry conditions in which reactions play an important role, are presented and compared with results from experiments and other computational fluid dynamics simulations. The differences are discussed and evaluated. Nomenclature A r = constant for forward reaction rate for reaction r A i;r , a i;r = coefficient for equilibrium constant for reaction r K eq;r = equilibrium constant for reaction r K f;r , K b;r = forward and backward reaction-rate coefficient M i = molecular weight of species i r = reaction r T = translational-rotational temperature T a = geometrically averaged temperature T v m = vibrational temperature of molecule m Z = coupling factor for vibration dissociation coupling process i;r = stoichiometric coefficient for reactant i in r i;r = stoichiometric coefficient for product i in r r = characteristic temperature of reaction r = total density i = density of species i ! i = mass production rate for species i
This paper presents a new flux splitting scheme for the Euler equations. The proposed scheme termed TV-HLL is obtained by following the Toro-Vazquez splitting (Toro and Vázquez-Cendón, 2012) and using the HLL algorithm with modified wave speeds for the pressure system. Here, the intercell velocity for the advection system is taken as the arithmetic mean. The resulting scheme is more accurate when compared to the Toro-Vazquez schemes and also enjoys the property of recognition of contact discontinuities and shear waves. Accuracy, efficiency, and other essential features of the proposed scheme are evaluated by analyzing shock propagation behaviours for both the steady and unsteady compressible flows. The accuracy of the scheme is shown in 1D test cases designed by Toro.
PurposeTo compute the Navier‐Stokes equations of a non‐equilibrium weakly ionized air flow. This can help to have a better description of the flow‐field and the wall heat transfer in hypersonic conditions.Design/methodology/approachThe numerical approach is based on a multi block finite volume method and using a Riemann's solver based on a MUSCL‐TVD algorithm. In the flux splitting procedure the modified speed of sound, due to the electronic mode, is implemented.FindingsA good description of the shock standoff distance, of the wall heat fluxes and of the peak of electron density number in the shock layer.Research limitations/implicationsThe radiative effects are not included in this paper. For the very high Mach numbers, this can modify the shock layer parameters.Practical implicationsThe knowledge of the wall heat transfer in the re‐entry body problems.Originality/valueThe building of a robust numerical code in order to well describe hypersonic air flow in high Mach numbers.
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