Numerical Simulation of Shock Tubes Using Shock Tracking in an Overset Formulation

Collen, Peter L.; McGilvray, Matthew; Mare, Luca di

doi:10.2514/1.j059829

Cited by 9 publications

(11 citation statements)

References 26 publications

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“…The deviation of the experimental data from the LASTA prediction is thought to be caused by formation of a vortical mixing region at the contact surface between the driver and test gas. Axisymmetric simulations by Satchell et al (2021) has shown that greater rates of SSV lead to increased deformation of this interface region. This results in vortices which can be on the order of the tube diameter.…”

Section: The Lasta Radiance Resultsmentioning

confidence: 99%

“…Axisymmetric simulations by Satchell et al. (2021) has shown that greater rates of SSV lead to increased deformation of this interface region. This results in vortices which can be on the order of the tube diameter.…”

Section: Spatial Radiance Variationmentioning

confidence: 99%

“…Depending on the magnitude of the deceleration, this could also be affected by vortices at the interface (Satchell et al. 2021) that cause a departure from both the nominal test condition and the prediction of the LASTA code.…”

Section: Shock Deceleration Effects On Test Slug Morphologymentioning

confidence: 99%

“…This may also suggest why certain past experiments have appeared to achieve radiance levels closer to equilibrium than might be expected: less of the shock history is visible, and so the maximum level of radiance observed is far below that which would be expected given the shock speed even a metre further upstream. Depending on the magnitude of the deceleration, this could also be affected by vortices at the interface (Satchell et al 2021) that cause a departure from both the nominal test condition and the prediction of the LASTA code.…”

Section: Effect Of Shock Deceleration Ratementioning

confidence: 99%

See 3 more Smart Citations

The influence of shock speed variation on radiation and thermochemistry experiments in shock tubes

Collen¹,

Mare²,

Mare³

et al. 2022

J. Fluid Mech.

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Shock tubes are a crucial source of experimental data for the aerothermodynamic modelling of atmospheric entry vehicles. Notably, many chemical-kinetic and radiative models are validated directly against optical measurements from these facilities. Typically, the incident shock speed at the location of the experimental measurement is taken to be representative of the test slug; however, the shock velocity can vary substantially upstream of this location. These variations have been long posited as a source of disagreement with computational predictions, although a definitive link has proved elusive. This work describes a series of experiments which aim to isolate and confirm the importance of the shock deceleration effect. This is achieved by generating different shock trajectories and comparing the post-shock trends in atomic oxygen emission and electron density. These trends are shown to be directly linked to the upstream shock speed variations using a recently developed numerical tool (LASTA). The close agreement of the comparisons confirms the importance of shock speed variation for shock tube experiments; these findings have direct and potentially critical relevance for all such studies, both past and present.

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Section: The Lasta Radiance Resultsmentioning

confidence: 99%

Section: Spatial Radiance Variationmentioning

confidence: 99%

Section: Shock Deceleration Effects On Test Slug Morphologymentioning

confidence: 99%

Section: Effect Of Shock Deceleration Ratementioning

confidence: 99%

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The influence of shock speed variation on radiation and thermochemistry experiments in shock tubes

Collen¹,

Mare²,

Mare³

et al. 2022

J. Fluid Mech.

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“…This is due to having a finite driver section length, change in volume if a free piston driver is used or transient heating processes if a deflagration, detonation or arc heating driver are used [2]. Additionally, the diaphragm rupture is not an instantaneous process and can introduce a rapid acceleration of the shock and subsequent deceleration, substantially influencing shock tube performance [3,4]. Thermochemistry also plays a role in the variation of shock speed [5,6].…”

Section: Introductionmentioning

confidence: 99%

Analytical Method of Evaluating Nonuniformities in Shock Tube Flows: Theory and Development

McGilvray

Mare

2022

AIAA Journal

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Shock tube experiments are a cornerstone of investigations into the hypersonic flight environment. However, the actual flow through the basic shock tube has not been well characterised in the literature, and nonuniformities arising in the test gases are not well understood. This work produces a quasi-one-dimensional analytical methodology for predicting the nonuniformities in the post-shock test gas based exclusively on the experimentally measured history of shock speed down the tube. Wave effects extracted from shock speed variations are shown to provide all information necessary in order to reconstruct the test slug from any particular experiment. Accurate representation of flow dynamics is initially checked against Argon test cases following accelerating and decelerating shock trajectories, each with a tube-end Mach number of 6.5 and a fill pressure of 66.66 Pa in a tube of 100 mm diameter. Agreement between the method and results from a viscous, axisymmetric Navier-Stokes solution is found to within 1% in pressure and temperature.

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Numerical investigation of the reflection of unsteady decelerating incident shock waves

Wang,

Han,

Liu

et al. 2024

Physics of Fluids

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The incident shock attenuation phenomenon in shock tube has received widespread interest because of its inevitable influence on experimental gas properties. However, few studies have investigated the cascading effects of the resulting nonuniformity on shock reflection in shock tunnels before the nozzle. This paper describes a numerical study on the unsteady reflection of a decelerating incident shock driven by a decelerating piston, as a simplification of the complex nonideal factors. The initial decay and uniform parameter distributions are generated based on the non-inertial frame. The results indicate that the existence of the nonuniform area forces the reflected shock wave region to undergo a transition process of attenuation and then stability. The final values of the gas parameters in zone 5 will, therefore, deviate from those given by the traditional relation for an ideal shock tube, which are only dependent on the terminal shock Mach number. This affects the determination of the total temperature T5, which is difficult to measure directly. We discuss the reconstruction of the nonuniform region with the attenuation trajectory of the incident shock wave and find that there is no one-to-one correspondence between this trajectory and the resulting nonuniformity, which introduces additional uncertainties to the predictions. Thus, an analogy method is developed through the multilevel block building algorithm, allowing the total temperature T5 to be determined using the total pressure p5 considering the effect of nonuniformity. Further assessments verify the applicability of this method in cases with multidimensional and viscous interactions.

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Numerical Simulation of Shock Tubes Using Shock Tracking in an Overset Formulation

Cited by 9 publications

References 26 publications

The influence of shock speed variation on radiation and thermochemistry experiments in shock tubes

The influence of shock speed variation on radiation and thermochemistry experiments in shock tubes

Analytical Method of Evaluating Nonuniformities in Shock Tube Flows: Theory and Development

Numerical investigation of the reflection of unsteady decelerating incident shock waves

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