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首页> 外文会议>AIAA international space planes and hypersonic systems and technologies conference >Numerical Simulation for the Effects of Angles of Attack on Two- and Three-Dimensional Rarefied Hypersonic Cavity Flows Using the Direct Simulation Monte Carlo Method
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Numerical Simulation for the Effects of Angles of Attack on Two- and Three-Dimensional Rarefied Hypersonic Cavity Flows Using the Direct Simulation Monte Carlo Method

机译：使用直接模拟蒙特卡罗方法数值模拟攻角对二维和三维稀疏高超声速腔流的影响

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A fundamental prerequisite for the re-entry of aerospace vehicles is a reliable thermal protection system. For simplicity, in the thermal load computations, it is assumed that vehicles have a smooth surface. However, discontinuities or imperfections usually exist due to some inevitable reasons. To operate safely, it is necessary to predict the flow-field structure and consequently undesired thermal loads. The present work investigates rarefied hypersonic flows over a flat plate with two-dimensional and three-dimensional (3-D) cavities by employing the direct simulation Monte Carlo (DSMC) method, focusing on the effect of angles of attack (AOAs) and the 3-D property on flow structure inside the cavity and aerodynamic surface quantities. It was found that only one primary recirculation structure was formed inside the cavity at low AOAs, while a second vortex system was produced just beneath the primary one when the angle of attack is increased to 30. As AOAs grow, more high-speed gas molecules coming from the main stream are able to penetrate deeper into the cavity, not only augmenting densities inside the cavity and making the "dead-water" region shrink, but also leading to a remarkable increase in heat flux and pressure over the cavity surfaces. The assumption of two-dimensionalities would overestimate heat transfer to and pressure on the cavity surfaces. In the 3-D cavity configuration, the two additional surfaces play a role of a frictional wall and an energy sink, serving to not only block the entry of gas molecules coming from the main stream into the cavity, causing a reduction in the density inside the cavity, but also lighten the burden of heat loads of all the three cavity surfaces, resulting in a decrease in heat flux and pressure over them.
机译：再入航空航天器的基本前提是可靠的热保护系统。为了简单起见，在热负荷计算中，假定车辆具有光滑的表面。但是，由于某些不可避免的原因，通常会出现不连续或不完美的情况。为了安全运行，必须预测流场结构，并因此预测不希望的热负荷。本工作通过采用直接模拟蒙特卡洛（DSMC）方法研究二维和三维（3-D）腔的平板上稀有高超音速流动，重点研究迎角（AOA）和入射角的影响。腔体内流动结构的3维特性和空气动力学表面量。发现在低AOAs时，腔体内仅形成一个主要的再循环结构，而当迎角增加到30时，在主要的正下方形成了第二个涡旋系统。随着AOAs的增长，更多的高速气体分子来自主流的气体能够更深地渗透到空腔中，不仅增加了空腔内部的密度并使“死水”区域缩小，而且导致空腔表面的热通量和压力显着增加。二维的假设会高估向模腔表面的传热和模腔表面的压力。在3-D腔体配置中，这两个附加表面起着摩擦壁和能量吸收器的作用，不仅用于阻止来自主流的气体分子进入腔体，从而导致内部密度降低空腔，但也减轻了所有三个空腔表面的热负荷，从而降低了它们的热通量和压力。

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