Numerical simulation for the hypersonic flow structure and thermal environment of non-rectangular cavities in the rarefied slip regime
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摘要:
为了量化高超声速飞行器表面防热瓦缝隙的局部压力和热载荷，采用直接模拟Monte Carlo (direct simulation Monte Carlo, DSMC) 方法模拟了稀薄滑移流区的防热瓦缝隙流动，考虑3类缝隙外形，即标准矩形缝隙、前部较浅缝隙和后部较浅缝隙，获得缝隙底部形状变化对缝隙内部流动特征、缝隙表面压力和热环境的影响规律。结果表明：缝隙底部形状的变化几乎不影响缝隙顶部及其附近的流场，包括流线样式、涡核位置、分离/再附处的密度分布，从而对缝隙下游侧面顶部表面压力和热流的影响也可以忽略。然而，相对于标准矩形缝隙，缝隙前部或后部变浅都会导致其底面热流变大，尤其是缝隙后部变浅甚至会使得底面的峰值热流增大近100倍。防热瓦缝隙底面一般直接就是飞行器表面，在航天器防热设计中，应特别注意这类缝隙后部较浅情况下的底面压力和热载荷。
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关键词:
- 稀薄流 /
- 滑移流 /
- 高超声速 /
- 凹腔 /
- 直接模拟Monte Carlo (DSMC)
Abstract:In order to quantify the local high pressure and heat loads due to cavities or imperfections on the surface of hypersonic vehicles, the direct simulation Monte Carlo (DSMC) was utilized to simulate the rarefied hypersonic flows over cavities in the slip regime. Three kinds of cavities were taken into account: the standard rectangular cavity, the shallower-front cavity, and the shallower-back cavity, for the purpose of gaining the effects of cavity-floor shape on flow characteristics inside the cavity, surface pressure and heat transfer to the cavity surfaces. Results showed that the cavity-floor shape had little influence on flow characteristics, including the streamline pattern, vortex-core position and density distribution, inside the upper part of cavities. Therefore, the surface pressure and heat transfer to the upper part of the aft wall of the cavity was kept unchanged when the front or back part of the cavity floor became shallower. However, in comparison with the standard rectangular cavity, both the shallower-front and shallower-back cavities suffered more severe heat loads on the cavity floor. Especially, the peak value of heat transfer to the cavity floor in the case of shallower-back cavity was 100 times larger than the corresponding value in the standard rectangular cavity. In the design of spacecraft, the cavity floor is exactly taken as the spacecraft surface, so much attention should be paid to the pressure and heat loads on the cavity floor in case of shallower-back cavity.
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Key words:
- rarefied gas flows /
- slip regime /
- hypersonic flows /
- cavity /
- direct simulation Monte Carlo (DSMC)
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图 1 缝隙绕流、计算域和边界条件示意图
Figure 1. Schematic drawing of flows past cavities, computational domain and boundary condition
图 2 非矩形缝隙示意图 （L=3 mm、 D=6 mm）
Figure 2. Schematic drawing of four non-rectangular cavities （L=3 mm, D=6 mm）
图 4 后部较浅缝隙 （DAW=2 mm） 的3套网格
Figure 4. Three sets of grids for the case of the shallower-back cavity （DAW=2 mm）
图 5 后部较浅缝隙 （DAW=2 mm） 算例中网格尺寸与分子平均自由程之比等值线
Figure 5. Contours of the ratio of grid size to local mean free path in the shallower-back cavity （DAW=2 mm）
图 6 后部较浅缝隙 （DAW=2 mm） 算例中时间步长与平均碰撞时间之比等值线
Figure 6. Contours of the ratio of time step to local mean collison time in the shallower-back cavity （DAW=2 mm）
图 7 不同网格/时间步长给出的后部较浅缝隙 （DAW=2 mm） 底面表面压力系数和表面传热系数分布
Figure 7. Distributions of surface pressure coefficients and surface heat transfer coefficients over the cavity floor of the shallower-back cavity （DAW=2 mm） for the three grids and time steps
图 8 不同形状的缝隙内部无量纲密度ρ/ρ∞等值线及流场结构
Figure 8. Contours of the dimensionless density and streamline traces for different cavities
图 9 不同形状缝隙的底面表面压力系数和表面传热系数分布
Figure 9. Distributions of surface pressure and surface heat transfer coefficients over the cavity floor for different cavities
图 10 不同形状缝隙的下游侧面表面压力系数和表面传热系数分布
Figure 10. Distributions of surface pressure and surface heat transfer coefficients over the aft wall for different cavities
表 1 自由来流条件参数
Table 1. Freestream parameters
参数 数值 海拔高度H/km 60 来流速度u∞/（m/s） 7900.63 来流温度T∞/K 247.021 来流压力p∞/Pa 21.96 来流密度ρ∞/10−4 （kg/m3） 3.095 
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表 2 验证算例来流条件
Table 2. Freestream parameters for validation cases
参数 数值 H/km 70 u∞/（m/s） 7456.00 T∞/K 220.0 p∞/Pa 5.53 ρ∞/10−5 （kg/m3） 8.753
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表 3 确认算例的网格和时间步长条件
Table 3. Grid sizes and time steps in verification cases
算例 网格数量 时间步长/10−9 s 1 265515 7.0 2 522420 5.0 3 1026051 3.5
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表 4 不同形状缝隙对应的涡核位置
Table 4. Positons of vortex core for different cavities
缝隙形状 涡核位置/（mm, mm） 标准矩形 （0.103760886, −1.295302695） DFW=4 mm （0.098350767, −1.298841339） DFW=2 mm （0.119020723, −1.236596170） DAW=4 mm （0.098017992, −1.296382456） DAW=2 mm （0.087573748, −1.229323613）
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[1] PALHARINI R C,SCANLON T J,WHITE C. Chemically reacting hypersonic flows over 3D cavities: flowfield structure characterisation[J]. Computers and Fluids,2018,165: 173-187. doi: 10.1016/j.compfluid.2018.01.029 [2] NESTLER D E,SAYDAH A R,AUXER W L. Heat transfer to steps and cavities in hypersonic turbulent flow[J]. AIAA Journal,1969,7(7): 1368-1370. doi: 10.2514/3.5351 [3] EVERHART J L,GREENE F A,PALMER G E,et al. Turbulent supersonic/hypersonic heating correlations for open and closed cavities[J]. Journal of Spacecraft and Rockets,2010,47(4): 545-553. doi: 10.2514/1.46877 [4] LAWSON S J,BARAKOS G N. Review of numerical simulations for high-speed,turbulent cavity flows[J]. Progress in Aerospace Sciences,2011,47(3): 186-216. doi: 10.1016/j.paerosci.2010.11.002 [5] CHAPMAN D. A theoretical analysis of heat transfer in regions of separated flow: NACA,Technical Note TN 3792 [R]. Washington DC: National Advisory Committee for Aeronautics,1956 [6] NICOLL K M. A study of laminar hypersonic cavity flows[J]. AIAA Journal,1964,2(9): 1535-1541. doi: 10.2514/3.2626 [7] JACKSON A P,HILLIER R,SOLTANI S. Experimental and computational study of laminar cavity flows at hypersonic speeds[J]. Journal of Fluid Mechanics,2001,427: 329-358. doi: 10.1017/S0022112000002433 [8] 邱波,张昊元,国义军,等. 高超声速飞行器表面横缝旋涡结构及气动热环境数值模拟[J]. 航空学报,2015,36(11): 3515-3521. QIU Bo,ZHANG Haoyuan,GUO Yijun,et al. Numerical investigation for vortexes and aerodynamic heating environment on transverse gap on hypersonic vehicle surface[J]. Acta Aeronautica et Astronautica Sinica,2015,36(11): 3515-3521. (in ChineseQIU Bo, ZHANG Haoyuan, GUO Yijun, et al. Numerical investigation for vortexes and aerodynamic heating environment on transverse gap on hypersonic vehicle surface[J]. Acta Aeronautica et Astronautica Sinica, 2015, 36(11): 3515-3521. (in Chinese) [9] PALHARINI R C,SCANLON T J,REESE J M. Aerothermodynamic comparison of two- and three-dimensional rarefied hypersonic cavity flows[J]. Journal of Spacecraft and Rockets,2014,51(5): 1619-1630. doi: 10.2514/1.A32746 [10] PALHARINI R C,SANTOS W F N. The impact of the length-to-depth ratio on aerodynamic surface quantities of a rarefied hypersonic cavity flow[J]. Aerospace Science and Technology,2019,88: 110-125. doi: 10.1016/j.ast.2019.03.007 [11] PAOLICCHI L T L C,SANTOS W F N. Length-to-depth ratio effects on aerodynamic surface quantities of a hypersonic gap flow[J]. AIAA Journal,2018,56(2): 780-792. doi: 10.2514/1.J055826 [12] 靳旭红,黄飞,程晓丽,等. 稀薄流区高超声速飞行器表面缝隙流动结构及气动热环境的分子模拟[J]. 航空动力学报,2019,34(1): 201-209. JIN Xuhong,HUANG Fei,CHENG Xiaoli,et al. Monte Carlo simulation for the flow-field structure and aerodynamic heating due to cavities on hypersonic vehicle surfaces in the rarefied flow regime[J]. Journal of Aerospace Power,2019,34(1): 201-209. (in ChineseJIN Xuhong, HUANG Fei, CHENG Xiaoli, et al. Monte Carlo simulation for the flow-field structure and aerodynamic heating due to cavities on hypersonic vehicle surfaces in the rarefied flow regime[J]. Journal of Aerospace Power, 2019, 34(1): 201-209. (in Chinese) [13] 靳旭红,黄飞,程晓丽,等. Maxwell气固相互作用模型对稀薄高超声速凹腔绕流流动特征和热环境的影响[J]. 航空学报,2021,42(3): 124118. JIN Xuhong,HUANG Fei,CHENG Xiaoli,et al. Effect of Maxwell gas-surface interaction models on flow characteristics and thermodynamic properties of rarefied hypersonic cavity flows[J]. Acta Aeronautica et Astronautica Sinica,2021,42(3): 124118. (in ChineseJIN Xuhong, HUANG Fei, CHENG Xiaoli, et al. Effect of Maxwell gas-surface interaction models on flow characteristics and thermodynamic properties of rarefied hypersonic cavity flows[J]. Acta Aeronautica et Astronautica Sinica, 2021, 42(3): 124118. (in Chinese) [14] JIN Xuhong,WANG Bing,CHENG Xiaoli,et al. Effects of corner rounding on aerothermodynamic properties in rarefied hypersonic flows over an open cavity[J]. Aerospace Science and Technology,2021,110: 106498. doi: 10.1016/j.ast.2021.106498 [15] JIN Xuhong,HUANG Fei,MIAO Wenbo,et al. Effects of the boundary-layer thickness at the cavity entrance on rarefied hypersonic flows over a rectangular cavity[J]. Physics of Fluids,2021,33(3): 036116. doi: 10.1063/5.0045056 [16] GUO Guangming,LUO Qin. Flowfield structure characteristics of the hypersonic flow over a cavity: from the continuum to the transition flow regimes[J]. Acta Astronautica,2019,161: 87-100. doi: 10.1016/j.actaastro.2019.05.023 [17] MORGENSTERN A Jr,CHOKANI N. Hypersonic flow past open cavities[J]. AIAA Journal,1994,32(12): 2387-2393. doi: 10.2514/3.12304 [18] BIRD G A. Approach to translational equilibrium in a rigid sphere gas[J]. Physics of Fluids,1963,6(10): 1518-1519. doi: 10.1063/1.1710976 [19] WAGNER W. A convergence proof for Bird’s direct simulation Monte Carlo method for the Boltzmann equation[J]. Journal of Statistical Physics,1992,66: 1011-1044. doi: 10.1007/BF01055714 [20] BIRD G A. Molecular gas dynamics and the direct simulation of gas flows[M]. Oxford,UK: Clarendon Press,1994. [21] BIRD G A. Monte Carlo simulation of gas flows[J]. Annual Review of Fluid Mechanics,1978,10: 11-31. doi: 10.1146/annurev.fl.10.010178.000303 [22] JIN Xuhong,CHENG Xiaoli,WANG Qiang,et al. Numerical simulation for rarefied hypersonic flows over non-rectangular deep cavities[J]. Physics of Fluids,2022,34(8): 086108. doi: 10.1063/5.0102685 [23] BORGNAKKE C,LARSEN P S. Statistical collision model for Monte Carlo simulation of polyatomic gas mixture[J]. Journal of Computational Physics,1975,18(4): 405-420. doi: 10.1016/0021-9991(75)90094-7 -
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