Numerical Simulations of Shock Propagation Under Strong Nonequilibrium Conditions

Chandel, Durgesh; Nompelis, Ioannis; Candler, Graham V.

doi:10.2514/1.t5882

Cited by 6 publications

(1 citation statement)

References 27 publications

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“…The exception may be if an advanced optical technique such as tuneable diode laser absorption spectroscopy [4] or coherent anti-stokes Raman spectroscopy [5] is used, but these techniques are complex, difficult to set up and generally cannot be done simultaneously with the experiments, which means an individual freestream estimate for each shot cannot be obtained. Full-facility time-accurate Navier-Stokes simulations are sometimes used to characterize these test conditions [6][7][8]; however, an obvious disadvantage is that an individual calibration for each run is impractical due to the computational time required. This is unless a perfectly steady flow is assumed and only the nozzle flow is simulated to ease the computational burden [9,10], in which case the result would not be time-resolved.…”

Section: Introductionmentioning

confidence: 99%

Characterization of reflected shock tunnel air conditions using a simple method

Olivier

Wen

et al. 2022

Physics of Fluids

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A new method to characterize air test conditions in hypersonic impulse facilities is introduced. It is a hybrid experimental-computational rebuilding method which uses the Fay-Riddell correlation with corrections based on thermochemical nonequilibrium computational fluid dynamic results. Its benefits include simplicity and time-resolution, and, using this method, a unique characterization can be made for each individual experimental run. Simplicity is achieved by avoiding the use of any optical techniques and overly expensive numerical computations while still maintaining accuracy. Without making any assumptions to relate the reservoir conditions to the nozzle exit conditions, the work done characterizing four test conditions in a reflected shock tunnel is presented. In this type of facility, shock compression is used to produce an appropriate reservoir which is then expanded through a nozzle to produce hypersonic flow. Particular focus is given to the nozzle exit total enthalpy where a comparison is made with the reservoir enthalpy obtained using the measured shock speed and pressure in the shock tube. Good agreement is observed in all cases providing validation of the new approach. Additionally, static pressure measurements showed clearly that conditions III and IV have a thermochemical state which likely froze shortly after the nozzle throat. Also, the nozzle flow is shown to be almost isentropic. Due to the simplicity of the current method, it can be easily implemented in existing facilities to provide an additional independent estimate alongside existing results.

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Section: Introductionmentioning

confidence: 99%

Characterization of reflected shock tunnel air conditions using a simple method

Olivier

Wen

et al. 2022

Physics of Fluids

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Influence of Vibration–Dissociation Coupling and Number of Reactions in Hypersonic Nonequilibrium Flows

Kane

Peetala

2022

Journal of Fluids Engineering

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During the atmospheric cruising of a hypersonic vehicle, the flow field between the shock wave and vehicle surface is characterized by thermal and chemical non-equilibrium. Therefore an understanding of nonequilibrium flows is essential for the efficient design of a hypersonic vehicle. The present numerical study is carried on the various canonical configuration to study the thermochemical non-equilibrium effects in hypersonic flows. The influence of vibration-dissociation (V-D) coupling method and reaction model on shock standoff distance (SSD), vibrational relaxation of gases and surface properties has been investigated. A finite volume method-based solver using open source platform openFOAM has been developed to analyse the thermochemical non-equilibrium effects in the hypersonic flow field. It has been observed that thermal and chemical non-equilibrium flow assumptions significantly affect SSD and hence these assumptions are necessary to study the cases with a higher degree of non-equilibrium. The vibrational relaxation of diatomic gases in air is influenced by the number of reactions. While the V-D coupling method used to calculate reaction rate constants has a negligible impact on the vibrational relaxation process. Moreover, the V-D coupling method and number of reactions have a negligible effect on surface pressure. But in the case of surface heat flux, the 11 reaction model predicts higher peak values than the 17 reaction model.

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