Superorbital expansion tube operation: Estimates of Flow conditions via numerical simulation

Jacobs, Peter A.; Silvester, Todd; Morgan, Richard G.; Scott, Marcia S.; Gollan, Rowan; McIntyre, Timothy J.

doi:10.2514/6.2005-694

Cited by 21 publications

(10 citation statements)

References 10 publications

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“…Second, the LENS-XX facility is unique in that it employs a moderately heated hydrogen driver and emission comes only from the shock layer. Other high enthalpy facilities use piston driven, arc heated, or combustion drivers [6][7][8] which are often as hot as the shock-layer gas itself so a spectrometer at the stagnation point of a model will be unable to distinguish between the emission that it sees from the shock layer and that from the driver. Third, the large size of the facility provides a very large inviscid core flow to test models either in the 60-cm (24") tube test section or the larger 240-cm (96") test section.…”

Section: A Lens-mentioning

confidence: 99%

High Enthalpy Studies of Capsule Heating in an Expansion Tunnel Facility

Dufrene

MacLean

Holden

2012

43rd AIAA Thermophysics Conference

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Measurements were made on an Orion heat shield model to demonstrate the capability of the new LENS-XX expansion tunnel facility to make high quality measurements of heat transfer distributions at flow velocities from 3 km/s (h 0 = 5 MJ/kg) to 8.4 km/s (h 0 = 36 MJ/kg). Thirty-nine heat transfer gauges, including both thin-film and thermocouple instruments, as well as four pressure gauges, and high-speed Schlieren were used to assess the aerothermal environment on the capsule heat shield. Only results from laminar boundary layer runs are reported. A major finding of this test series is that the highenthalpy, low-density flows displayed surface heating behavior that is observed to be consistent with some finite-rate recombination process occurring on the surface of the model. It is too early to speculate on the nature of the mechanism, but the response of the gages on the surface seems generally repeatable and consistent for a range of conditions. This result is an important milestone in developing and proving a capability to make measurements in a ground test environment and extrapolate them to flight for conditions with extreme non-equilibrium effects. Additionally, no significant, isolated stagnation point augmentation ("bump") was observed in the tests in this facility. Cases at higher Reynolds number seemed to show the greatest amount of overall increase in heating on the windward side of the model, which may in part be due to small-scale particulate.

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Section: A Lens-mentioning

confidence: 99%

High Enthalpy Studies of Capsule Heating in an Expansion Tunnel Facility

Dufrene

MacLean

Holden

2012

43rd AIAA Thermophysics Conference

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“…Finite rate chemistry computational fluid dynamics (CFD) simulation results of the facility [48] were shown to overestimate the freestream Mach number and other flow properties, due to an oversimplification of the driver and other flow processes , and are not included in this paper. Estimates of the freestream conditions shown in Table 1 were obtained from a modified JUMP analysis.…”

Section: Flow Conditionsmentioning

confidence: 99%

Skin-Friction Measurements and Flow Establishment Within a Long Duct at Superorbital Speeds

Silvester

Morgan

2008

AIAA Journal

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The successful operation of an acceleration-compensated skin-friction transducer in test times and at total enthalpies offered by the X3 superorbital expansion tube was demonstrated. Localized measurements of skin friction and heat flux along the centerline of an inner wall of a 1-m-long rectangular diverging duct were reported. The laminar measurements were obtained in air with a freestream Mach number of 10 and stagnation enthalpy of 40 MJ=kg. Steady heat flux and skin-friction levels confirmed the establishment of quasi-steady flow periods of 350 s along the length of the duct. Experimental results were shown to be in excellent agreement with computational fluid dynamics estimates. The measured Reynolds analogy factor was shown to be slightly higher than theoretical flat-plate predictions and computational fluid dynamics estimates, though agreement was to within experimental uncertainty. Estimates of the gas-phase and surface Damköhler numbers suggested that although the boundary layer was likely to be chemically frozen, recombination at the surface may be occurring. The experimental data and computational fluid dynamics results for a thermochemical nonequilibrium gas and catalytic and noncatalytic walls indicated that the effects of gas-phase and surface chemical reactions were negligible. Nomenclatureof the density-viscosity product evaluated at the wall k R = specific recombination rate coefficient, m 6 =mol s k w = surface reaction rate, m=s L = length of duct (1 m) P = static pressure, Pa Pr = Prandtl number < = universal gas constant, 8:31451 J=mol K Re x = Reynolds number Sc = Schmidt number T = static temperature, K t = time, s u = velocity, m=s V = voltage, V x = distance from the leading edge, m = dynamic viscosity coefficient, Pa s = density, kg=m 3 = characteristic time, s w = measured wall shear stress, Pa g = gas-phase recombination Damköhler number s = surface recombination Damköhler number ! = temperature exponent Subscripts acc = acceleration component d = diffusion e = boundary-layer edge value P = pressure component r = reaction s = surface reaction sf = shear force component w = wall value 1 = measuring element piezoceramic 2 = acceleration element piezoceramic 1 = freestream conditions (expansion-tube exit conditions)

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“…Jacobs [15] first used perfect gas model and laminar flow simulation to study the test flow properties of X-2 and further included the finite-rate chemical kinetics and strong viscous effects in the expansion tube for the simulation of SET X-3 [16]. The turbulent boundary layer in the expansion tube was simulated [17] in conjunction with the HYPULSE facility.…”

Section: Introductionmentioning

confidence: 99%

On the numerical technique for the simulation of hypervelocity test flows

Hu¹,

Wang²,

Jiang³

et al. 2015

Computers & Fluids

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a b s t r a c tA shock-expansion tube (SET) is one of the major ground test facilities to generate really high-enthalpy and hypervelocity test flows. However, the strong shock wave may give rise to chemically non-equilibrium characteristic flow feature in a SET. In addition, the test time duration of a SET is extremely short which leads to difficulties in measurements and flow diagnostics. It is therefore appropriate to consider employing CFD approach, coupled with available experimental data, to determine the characteristic of the test flow in a SET. The dispersion-controlled dissipative scheme (DCD) is used for our simulation of chemically non-equilibrium flows associated with a SET. In this paper, the several numerical issues which occur in the computational investigation of the test flow in our SET facility are discussed. A new flux splitting algorithm based on local characteristics is worked out for the DCD scheme to mitigate any spurious oscillations. With the mentioned updated DCD scheme, the computed results compare well with the experimental data provided for validation.

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Superorbital expansion tube operation: Estimates of Flow conditions via numerical simulation

Cited by 21 publications

References 10 publications

High Enthalpy Studies of Capsule Heating in an Expansion Tunnel Facility

High Enthalpy Studies of Capsule Heating in an Expansion Tunnel Facility

Skin-Friction Measurements and Flow Establishment Within a Long Duct at Superorbital Speeds

On the numerical technique for the simulation of hypervelocity test flows

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