The impact of the length-to-depth ratio on aerodynamic surface quantities of a rarefied hypersonic cavity flow

Palharini, Rodrigo Cassineli; Santos, Wilson F. N.

doi:10.1016/j.ast.2019.03.007

Cited by 27 publications

(5 citation statements)

References 41 publications

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“…Figure 1 shows the streamline patterns and dimensionless normal velocity inside the cavity of the current DSMC results and those presented in Ref. [33], where the three dimensionless normal velocity profiles are plotted with the data extracted from the three transversal sections defined by the dimensionless height of y = 0.25H, 0.5H, and 0.75H, respectively. The comparison of streamline patterns inside and around the cavity is displayed by Figs.…”

Section: Validation Of the Dsmc Codementioning

confidence: 88%

“…In order to verify the validity of our DSMC code in simulating hypersonic cavity flow in near space, the cavity with a length-to-depth ratio of 4 and under a freestream Mach number of 25 at the altitude of 70 km is used to carry out the DSMC code, and the detailed flow conditions are listed in Table 1 of Ref. [33]. Figure 1 shows the streamline patterns and dimensionless normal velocity inside the cavity of the current DSMC results and those presented in Ref.…”

Section: Validation Of the Dsmc Codementioning

confidence: 99%

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Investigation of hypersonic flows through a cavity with sweepback angle in near space using the DSMC method*

et al. 2021

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Near space has been paid more and more attentionin recent years due to its military application value. However, flow characteristics of some fundamental configurations (e.g., the cavity) in near space have rarely been investigated due to rarefied gas effects, which make the numerical simulation methods based on continuous flow hypothesis lose validity. In this work, the direct simulation Monte Carlo (DSMC), one of the most successful particle simulation methods in treating rarefied gas dynamics, is employed to explore flow characteristics of a hypersonic cavity with sweepback angle in near space by considering a variety of cases, such as the cavity at a wide range of altitudes 20–60 km, the cavity at freestream Mach numbers of 6–20, and the cavity with a sweepback angle of 30°–90°. By analyzing the simulation results, flow characteristics are obtained and meanwhile some interesting phenomena are also found. The primary recirculation region, which occupies the most area of the cavity, causes pressure and temperature stratification due to rotational motion of fluid inside it, whereas the pressure and temperature in the secondary recirculation region, which is a small vortex and locates at the lower left corner of the cavity, change slightly due to low-speed movement of fluid inside it. With the increase of altitude, both the primary and secondary recirculation regions contract greatly and it causes them to separate. A notable finding is that rotation direction of the secondary recirculation region would be reversed at a higher altitude. The overall effect of increasing the Mach number is that the velocity, pressure, and temperature within the cavity increase uniformly. The maximum pressure nearby the trailing edge of the cavity decreases rapidly as the sweepback angle increases, whereas the influence of sweepback angle on velocity distribution and maximum temperature within the cavity is slight.

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Section: Validation Of the Dsmc Codementioning

confidence: 88%

Section: Validation Of the Dsmc Codementioning

confidence: 99%

Investigation of hypersonic flows through a cavity with sweepback angle in near space using the DSMC method*

et al. 2021

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“…The simulations are performed assuming air as non-reacting rarefied perfect-gas. Several studies 34,35,73–76 have used this assumption where the chemical reactions were not considered. Table 5 lists the flow and simulation parameters.…”

Section: Methodsmentioning

confidence: 99%

“…Palharini et al. 34,35 examined the different length to depth ratios for hypersonic air flow for both 2 D and 3 D cavities using the DSMC method and evaluated the surface properties. Recently Leite et al.…”

Section: Introductionmentioning

confidence: 99%

DSMC simulation of rarefied gas flow over a 2D backward-facing step in the transitional flow regime: Effect of Mach number and wall temperature

Nabapure

2020

Proceedings of the Institution of Mechanical Engineers, Part G:

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Rarefied gas flow over a backward-facing step (BFS) is often encountered in separating flows prevalent in aerodynamic flows, engine flows, condensers, space vehicles, heat transfer systems, and microflows. Direct Simulation Monte Carlo (DSMC) is a powerful tool to investigate such flows. The purpose of this research is to assess the impact of Mach number and wall temperature on the flow and surface properties in the transitional flow regime. The Mach numbers considered are 5, 10, 25, 30, and the ratio of the temperature of the wall to that of freestream considered are 1, 2, 4, 8. The Reynolds number for the cases studied is 8.6, 17.2, 43, and 51.7, respectively. Typically the flow properties near the wall are found to increase with both Mach number and wall temperature owing to compressibility and viscous dissipation effects. The variation in flow properties is more sensitive to Mach number than the wall temperature. The surface properties are found to decrease with Mach number and increase with wall temperature. Moreover, in the wake of the step, the vortex’s recirculation length is reasonably independent of both free stream Mach number and wall temperature, whereas it decreases with Knudsen number.

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“…In contrast to previous studies, we have accounted for the effects of air ducts on a modified Orion CEV capsule and underlying physics in a rarefied hypersonic flow regime. The benchmark model is inspired by [11], but using CFD modelling in our study instead of the Direct Simulation Monte Carlo method. The key underlying physics include shockwaves, heat flux generation, surface temperatures, drag, and the flow pattern of the hypersonic flow.…”

Section: Introductionmentioning

confidence: 99%

Parametric Optimisation of Hypersonic Re-entry Capsules with Air-Duct Systems

Al Qubeissi,

Shaban,

Almohammadi

et al. 2023

Preprint

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This study focuses on the aerodynamic optimization of the re-entry capsule (REC) Orion Crew Exploration Vehicle (CEV) module, evaluating its performance using computational fluid dynamics (CFD). Three different models, namely Baseline, 2-Duct, and 4-Duct, are investigated under a wide range of flow speeds, from supersonic (Ma=1.6) to hypersonic (Ma=6) regimes. Thermofluids aspects, drag coefficient, surface heat flux, and the effectiveness of the modified geometry are assessed using aerodynamic and temperature-based models. The results show that the introduction of ducts in the 2-Duct and 4-Duct models leads to an average decrease in the drag coefficient of approximately 2.1% and 2.9%, respectively, compared to the baseline model, across all Mach numbers. The maximum reduction in drag coefficient is 3.55%, observed at Ma=1.4 using the 4-Duct capsule. However, it is found that the addition of extra ducts to the model increases the maximum heat transfer rate. Specifically, the heat flux is increased by up to 69% for the 4-Duct model at Ma=6, compared to the baseline model. On average, the heat flux is increased by approximately 28.6% for all conditions. The findings indicate that the introduction of ducts in the REC model improves its aerothermodynamic performance by reducing drag but also increases the heat transfer rate on the surface.

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The impact of the length-to-depth ratio on aerodynamic surface quantities of a rarefied hypersonic cavity flow

Cited by 27 publications

References 41 publications

Investigation of hypersonic flows through a cavity with sweepback angle in near space using the DSMC method*

Investigation of hypersonic flows through a cavity with sweepback angle in near space using the DSMC method*

DSMC simulation of rarefied gas flow over a 2D backward-facing step in the transitional flow regime: Effect of Mach number and wall temperature

Parametric Optimisation of Hypersonic Re-entry Capsules with Air-Duct Systems

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