Flow Nonuniformity in Shock Tubes Operating at Maximum Test Times

A numerical calculation is presented for the flow in a low-pressure shock tube. The evolution of the hot flow quantities due to mutual interaction between the boundary layer and inviscid hot flow are taken into account. A better knowledge of the unsteady evolution of this hot flow is so obtained, including the distribution of all parameters at the limiting regime. The computational results, with Argon as a driven gas, are in agreement with the different experimental results at usual measurement stations. Nomenclature= sound velocity = shock tube diameter = enthalpy = separation distance between shock and contact surface = maximum separation distance = mass loss term = shock Mach number = pressure = Prandtl number = shock tube radius = perfect gas constant = entropy = temperature = axial flow velocity = flow velocity = shock velocity = U S -(7= flow velocity in a shock-fixed coordinate system = radial flow velocity = laboratory coordinate system = density ratio across the shock = ratio of specific heats = boundary-layer thickness = displacement thickness T TH = density displacement thickness • = density = viscosity = test time = maximum test time = test time in ideal shock tube theory Subscripts c = conditions at the contact surface e = conditions in the inviscid hot flow / = conditions from ideal shock tube theory £ = conditions at the limiting regime S = conditions immediately behind the shock wave W = conditions at the wall 1 = conditions in the undisturbed flow ahead of the shock

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“…20 As for temperature and pressure, their distributions are very close and the maximum discrepancy is of the order of 4% for M s =2.4.…”

Section: Flow Variables At the Limiting Regimementioning

confidence: 84%

Interaction between the Unsteady Boundary Layer and Inviscid Hot Flow in a Shock Tube

Zeitoun

Imbert

1979

AIAA Journal

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“…During a significant part of the sphere motion, in the small-size shock tube, the sphere moves close to the contact surface. It is known that flow parameters in this region may exceed, up to 10 15%, the values reached immediately behind the shock wave front due to mass losses which take place through the wall boundary layer (Mirels 1966). This mass loss in the post shock flow causes the shock wave and the contact surface to approach a limiting separation distance called: "the maximum test time" 50 40 i,,,llll,l~q,lllll,…”

Section: Photo-electric Measurements In a Small-size Shock Tubementioning

confidence: 99%

“…x/D (Mirels 1964(Mirels , 1966. In order to avoid complicated calculations needed for correcting the flow properties due to this mass losses we adopted a simpler alternative.…”

Section: Photo-electric Measurements In a Small-size Shock Tubementioning

confidence: 99%

Acceleration of a sphere behind planar shock waves

Britan

Elperin

Igra

et al. 1995

Experiments in Fluids

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Experiments in Fluids zo (1995) 84 90 ~' Springer-Verlag 1995 planar shock waves 84 Abstract The paper presents the results of an investigation on the motion of a spherical particle in a shock tube flow. A shock tube facility was used for studying the acceleration of a sphere by an incident shock wave. Using different optical methods and performing experiments in two different shock tubes, the trajectory and velocity of a spherical particle were measured. Based upon these results and simple one-dimensional calculations, the drag coefficient of a sphere and shading effect of sphere interaction with a shock tube flow were studied. 1

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“…In addition, non-ideal effects, such as boundary layers, reduce the test time further and introduce disturbances that limit the uniformity of the test gas. 3,9,12 III. Computational setup A second-order, finite volume unstructured, compressible RANS solver was used for the unsteady flow computation.…”

Section: Introduction To the Stanford Expansion Tube Facilitymentioning

confidence: 99%

A Study of Expansion Tube Gas Flow Conditions for Scramjet Combustor Model Testing

Gamba

Adams

Iaccarino

2012

42nd AIAA Fluid Dynamics Conference and Exhibit

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The current work summarizes the efforts on the characterization of the unsteady gas flow process inside an expansion tube facility. The work is a combined numerical/experimental effort. Axisymmetric, viscous, unsteady RANS simulations of the operation of an expansion tube have been performed. Additionally, measurements of observable quantities have been carried out to validate the simulations and to gain detailed physical insight into the operation of the facility. Here, a comparison of transient wall static pressure, shock Mach numbers and stagnation point pressures at the tube outlet have been selected for comparison. The transient test gas flow is then analyzed on grounds of the results of the numerical simulation. Nomenclature wVector of conserved variables R Residual value vector ∆t Physical time step V Cell volume t * Pseudo-time Z m Mass mixture fraction n Time step number

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Flow Nonuniformity in Shock Tubes Operating at Maximum Test Times

Cited by 114 publications

References 5 publications

Interaction between the Unsteady Boundary Layer and Inviscid Hot Flow in a Shock Tube

Interaction between the Unsteady Boundary Layer and Inviscid Hot Flow in a Shock Tube

Acceleration of a sphere behind planar shock waves

A Study of Expansion Tube Gas Flow Conditions for Scramjet Combustor Model Testing

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