Rarefied gas effects on hypersonic flow over a transpiration-cooled flat plate

Appar, Ahilan; Bajpai, Aasheesh; Sivakumar, Udhaya K.; Naspoori, Srujan K.; Kumar, Rakesh

doi:10.1063/5.0131259

Cited by 4 publications

(1 citation statement)

References 36 publications

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“…Commonly used materials for the solid wall include layered plates, sintered particle porous materials [7] and sintered wire mesh porous structures [8]. When the coolant is a single-phase fluid without phase change within the porous wall, such as using various gases as the coolant, it is referred to as single-phase transpiration cooling, which is the focus of current transpiration cooling technologies [9][10][11][12]. When the coolant absorbs heat that undergoes phase change within the porous wall, such as using water as the coolant, it is termed as phase-change transpiration cooling, which performs great potential due to the large phase-change latent heat of the coolant for active thermal protection [13].…”

Section: Introductionmentioning

confidence: 99%

A modified local thermal non-equilibrium model of transient phase-change transpiration cooling for hypersonic thermal protection

Jin,

Zhao,

Yao

et al. 2024

Adv. Aerodyn.

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Aiming to efficiently simulate the transient process of transpiration cooling with phase change and reveal the convection mechanism between fluid and porous media particles in a continuum scale, a new two-phase mixture model is developed by incorporating the local thermal non-equilibrium effect. Considering the low-pressure and high overload working conditions of hypersonic flying, the heat and mass transfer induced by capillary and inertial body forces are analyzed for sub-cooled, saturated and super-heated states of water coolant under varying saturation pressures. After the validation of the model, transient simulations for different external factors, including spatially-varied heat flux, coolant mass flux, time-dependent external pressure and aircraft acceleration are conducted. The results show that the vapor blockage patterns at the outlet are highly dependent on the injection mass flux value and the external pressure, and the reduced saturation temperature at low external pressure leads to early boiling off and vapor blockage. The motion of flying has a large influence on the cooling effect, as the inertial force could change the flow pattern of the fluid inside significantly. The comparison of the results from 2-D and 3-D simulations suggests that 3-D simulation shall be conducted for practical application of transpiration cooling, as the thermal protection efficiency may be overestimated by the 2-D results due to the assumption of an infinite width length of the porous plate.

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Section: Introductionmentioning

confidence: 99%

A modified local thermal non-equilibrium model of transient phase-change transpiration cooling for hypersonic thermal protection

Jin,

Zhao,

Yao

et al. 2024

Adv. Aerodyn.

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Numerical study of gas–surface interface effects due to transpiration in a hypersonic flow over a blunt body

Appar,

Bajpai,

Kumar

2024

Physics of Fluids

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This paper investigates the impact of transpiration on a hypersonic flow over a cylinder, considering different degrees of rarefaction. The study analyzes the interaction between freestream argon gas flow at Mach 5 and transpiring argon gas at the fluid–solid interface at a velocity of 10 m/s. Freestream Knudsen numbers considered are 0.002, 0.01, 0.05, and 0.25, spanning from a continuum to rarefied regime. Flow simulations utilize the open-source direct simulation Monte Carlo solver, Stochastic PArallel Rarefied-gas Time-accurate Analyzer. The influence of transpiration on flow and surface properties is examined by comparing non-transpiration and transpiration cases. At all regimes, transpiration increases the normal shock stand-off distance, while a comparison of flow properties along the stagnation line reveals a reduction in the velocity and an increase in the post-shock temperature with transpiration. Surface heat flux comparison indicates that transpiring gas reduces heat flux on the cylinder's upstream-facing front surface at all Knudsen numbers. However, at Kn∞ = 0.25, a shift occurs, and surface heat flux starts increasing locally from the top/bottom point on the cylinder surface through the rear face of the cylinder. Furthermore, a test for the validity of the continuum-based blowing correction correlation function reveals the failure of the empirical model, even in the continuum regime at Kn∞ = 0.002, casting doubt on its applicability to vehicles with curvilinear blunt-body shapes. Additionally, a sensitivity analysis demonstrates that transpiring gas with a number density an order of magnitude higher than the freestream reduces stagnation peak heat flux by nearly 30%, while transpiring gas with a temperature two times higher than the freestream shows a ∼13% reduction.

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Transport cross sections and collision integrals for N(4S)–O(3P) and N(4S)–O(1D) interactions in high-temperature air plasmas

Ding,

Qin,

Liu

2024

Physics of Fluids

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Collisions between nitrogen (N) and oxygen (O) play a crucial role in determining transport coefficients in high-temperature atmospheres of Earth and planetary. In this study, the momentum transfer, viscosity, third-moment, and fourth-moment transport cross sections for the N(4S)–O(3P) and N(4S)–O(1D) interactions are reported in the collision energy range of 10−6–10 Hartree based on the classical and semiclassical methods. The new and accurate potential energy curves for N–O interactions, which are used to provide the input for calculations of the cross sections, are calculated based on the state-of-the-art ab initio method. The classical and semiclassical collision integrals are provided at 300–50 000 K, and the results support the calculation of transport coefficients in a third-order approximation. In particular, the collision data for the N(4S)–O(1D) interaction based on ab initio points are reported for the first time. The calculated transport cross sections and collision integrals are helpful for studies of modeling the high-temperature air plasmas.

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Rarefied gas effects on hypersonic flow over a transpiration-cooled flat plate

Cited by 4 publications

References 36 publications

A modified local thermal non-equilibrium model of transient phase-change transpiration cooling for hypersonic thermal protection

A modified local thermal non-equilibrium model of transient phase-change transpiration cooling for hypersonic thermal protection

Numerical study of gas–surface interface effects due to transpiration in a hypersonic flow over a blunt body

Transport cross sections and collision integrals for N(4S)–O(3P) and N(4S)–O(1D) interactions in high-temperature air plasmas

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