稀薄大气密度涨落对高空超高速飞行器气动性能的影响

地球周围的大气环境特性,随高度的上升,显著变化。对于本文关心的高度100km附近高超声速飞行器气动特性而言,稀薄大气密度涨落影响是一个重要的问题。按照大气层划分,高度100 km属于热层。热层的下界高度约86 km,上界高度与太阳活动有关,在太阳宁静期约为200 km,太阳活动期约500 km。热层下接中间层(高度50～86 km),上连电离层(高度80～1000 km),大气研究已知,中间层主要受重力波和湍流影响,电离层主要受太阳活动和地磁效应影响。高度100 km附近空域,处在热层下界,重力波、湍流、太阳活动和地磁效应等均有影响,理论上需要Navier-Stokes方程和Maxwell方程..

Comparison of the simulated and LIDAR measured atmospheric density and temperature in transitional flow regime

The understanding of the atmosphere in the transitional flow regime is quite limited,due to the limited accuracy of measurement data.In the proposed paper,the atmospheric density and temperature at around 100 km altitude are analyzed,by using numerical simulation,empirical model,satellite data an..

Mass flow rate and pressure distribution of three dimensional micro-channel gas flows

The theoretical solutions to the pressure distribution and mass flow rate of gas flows through three dimensional micro-channels with different cross-section shapes are obtained.Compared to the measured data of micro-channel experiments in Ref.[1],the solutions show that the side walls of the rect..

有限长度的过渡领域微槽道流动(—分析预测和试验的比较)(英文)

在连续介质和滑流区有限长度槽道内的稳定气流,通过整体质量守恒规律得到了沿槽道轴向的压力分布和质量流率的分析表达式。在过渡领域区,也提供了槽道流动压力分布的严格的动理学理论解。在Poiseuille流动的质量流率动理学理论解给定的情况下,压力分布的控制方程被证实是被前一作者从轴承润滑问题移植到解微槽道问题的退化Reynolds方程。同时得到了质量流率分析表达式,它们和现有试验数据的比较相符很好

有限长度的过渡领域三维微槽道流动

微槽道是微机电系统的重要装置,各种微管道中的气体流动特性是微机电系统设计和优化中的重要问题之一。Sharipov的综述文章系统的介绍了关于微管道流动的计算。当时的模型基本上以二维流动为主,一类是将垂直流向的截面简化,将其看作无限宽的矩形截面或轴对称的圆截面,考察流向的压力分布和质量流量;另一类以常压力梯度假设下的微管道作为基本问题,考察各种截面形状Poiseuille流动速度分布和质量流量。沈青先生通过质量守恒规律和无限宽的矩形截面的Poiseulle流动质量流率拟合公式得到了沿槽道轴向的压力分布和质量流率的分析表达式,提供了流动压力分布的严格的动理学理论解。本文通过整体质量守恒规律和不同形状..

非圆管截面poiseuille流动的统计模拟

本文用直接模拟Monte Carlo(DSMC)方法和信息保存(IP)方法模拟了矩形,六边形和半圆形截面的过渡领域Poiseuille流动。DSM方法和IP方法结果相互之间较好的符合,而IP方法的计算效率比DSMC方法的计算效率高得多。由这两种方法得到的质量流率与Hasegawa和Sone等人的BGK模型结果相符。通过用这两种方法对于不同宽高比矩形截面的计算,给出了侧壁面对质量流率和沿中心线的速度分布的影响

GAS FLOWS THROUGH MICRO-PIPES WITH DIFFERENT CROSS-SECTION SHAPES

不同形状微尺度管道（圆形、六边形、半圆形、不同宽高比的矩形）中的气体流动特性是微机电系统设计最为关心的问题之一．文中利用信息保存（IP）方法和直接模拟Monte Carlo（DSMC）方法进行研究，给出两种方法的计算结果相互符合，并与其它研究者的BGK模型方程计算结果进行了比较．对于微尺度管道中关心的低Mach数流动，IP方法的统计收敛效率明显优于DSMC方法,通过拟合IP和DSMC结果，给出了圆形、六边形、半圆形、不同宽高比的矩形截面情况下无量纲质量流率与等效Knudsen数的关系

Multiple-temperature kinetic model for continuum and near continuum flows

A gas-kinetic model with multiple translational temperature for the continuum and near continuum flow simulations is proposed. The main purpose for this work is to derive the generalized Navier-Stokes equations with multiple temperature. It is well recognized that for increasingly rarefied flowfields, the predictions from continuum formulation, such as the Navier-Stokes equations lose accuracy. These inaccuracies may be partially due to the single temperature assumption in the standard Navier-Stokes equations. Here, based on an extended Bhatnagar-Gross-Krook (BGK) model with multiple translational temperature, the numerical scheme for its corresponding Navier-Stokes equations is also constructed. In the current approach, the energy exchange between x, y, and z directions is modeled through the particle collision, and individual energy equation in different direction is obtained. The kinetic model, newly constructed is an enlarged system in comparison with Holway's ellipsoid statistical BGK model (ES-BGK). The detailed difference is presented in this paper. In the newly derived "Navier-Stokes" equations from the current model, all viscous terms are replaced by the temperature relaxation terms. The relation between the stress and strain in the standard Navier-Stokes equations is recovered only in the limiting case when the flow is close to the equilibrium, such as small temperature differences in different directions. In order to validate the generalized Navier-Stokes equations, we apply them to the study of Couette and Poiseuille flows with a wide range of Knudsen numbers. In the continuum flow regime, the standard Navier-Stokes solutions are precisely recovered. In the near continuum flow regime, the simulation results are compared with the direct simulation Monte Carlo solutions. The anomalous phenomena in the pressure and temperature distributions from the standard Navier-Stokes equations in the Poiseuille flow case at Kn=0.1 are well resolved by the generalized Navier-Stokes equations. This paper clearly shows that many thermal nonequilibrium phenomena in the near continuum flow regime can be well captured by modifying some assumptions in the standard Navier-Stokes equations

不同形状微管道中的气体流动

不同形状微尺度管道（圆形、六边形、半圆形、不同宽高比的矩形）中的气体流动特性是微机电系统设计最为关心的问题之一．文中利用信息保存（IP）方法和直接模拟Monte Carlo（DSMC）方法进行研究，给出两种方法的计算结果相互符合，并与其它研究者的BGK模型方程计算结果进行了比较．对于微尺度管道中关心的低Mach数流动，IP方法的统计收敛效率明显优于DSMC方法,通过拟合IP和DSMC结果，给出了圆形、六边形、半圆形、不同宽高比的矩形截面情况下无量纲质量流率与等效Knudsen数的关系