Testing of the Fluent Package in Calculation of Supersonic Flow in a Step Channel

Nonstationary supersonic flow of a nonviscous gas in a step channel with Mach number M = 3 is calculated using the FLUENT package. The accuracy of predictions is analyzed on different types of grids, including those with dynamic local adaptation, and on numerical schemes of different approximation orders.     

Simulation of a DC Discharge in a Transverse Supersonic Gas Flow

This study is devoted to the investigation of a dc discharge in a transverse gas flow. It is shown that the discharge may exist in several forms depending on the gas flow velocity. The standard stationary discharge similar to a discharge in still gas is realized if the displacement rate of the plasma boundary exceeds the gas flow velocity. The displacement rate of the plasma boundary in a diffusion model is defined by the relation V _f = 2 , where D _a is the ambipolar diffusion coefficient, and _i is the frontal ionization frequency. Otherwise, the discharge assumes the form of two plasma wakes formed by the cathode and anode, respectively. The surface of the plasma wakes is oriented at an angle to the flow velocity C _s (sin = V _f /C _s ). If sin is smaller than the ratio of the discharge sustaining voltage in the stationary regime U _st to the breakdown voltage U _bk , the discharge transforms into the pulse–periodic form, when the formation of a structure of the cathode and anode plasma wakes is interrupted by a new gas breakdown. A numerical simulation of the discharge properties is performed. The numerical simulation results are compared to the experimental ones.     

Supersonic Flow of Viscous Gas in a Flat Channel at High Values of the Reynolds Number

Based on numerical analysis of two-dimensional Reynolds equations using the differential model of turbulence, the structure of flow field and aerodynamic characteristics of a flat channel with variable cross section at the inlet Mach number of four is investigated in the range of Reynolds numbers Re = 10⁵–10⁷. According to the calculation results, the interaction between a shock and a laminar boundary layer results in the emergence of a closed separation zone. During interaction with a turbulent boundary layer, two flow schemes are possible, depending on the intensity of incident shock, namely, without and with separation. The extrapolation of calculation data to nonviscous flow (limiting transition Re ) shows that the classical scheme of regular reflection of the shock from a flat surface corresponds to interaction without separation. Corresponding to interaction with separation is the flow scheme with formation of a small closed separation zone in which a subsonic circulation flow takes place.     

新型超音速压气机内气固两相流场CFD模拟分析

为预测和预防压气机叶轮磨损，基于多相流理论对超音速压气机内的三维气固两相流场进行数值模拟。在分析中将压气机内的流场按可压缩气体处理，同时考虑温度对颗粒运动轨迹的影响。模拟结果表明，叶片出口端部前缘，温度达到最大，颗粒的运动速度也达到最大值。由此判明叶轮磨损最严重处位于叶片端部。     

对撞超声速射流场的数值模拟研究

为了探讨对撞式气流粉碎机内部的对撞超声速射流流场结构对粉碎过程的影响,本文中通过数值模拟的方法,对该流场结构进行了研究。通过建立不同的模型,对射流出口与对称平面的距离对粉碎过程的影响,以及射流外围的流动情况进行了分析,为高效气流粉碎机的设计提供了参考依据。     

Stabilization of Supersonic Combustion of Propane in an Expanding Aerodynamic Channel with the Use of Low-Temperature Plasma

High Temperature - Under the conditions of a nonstationary pulsating longitudinal-transverse discharge produced in a supersonic cold (T = 175 K) air flow, the combustion of a propane–air...     

Simulation of Thermionic Thermal Protection in a Supersonic Air Flow around a Spherically Blunted Cone

High Temperature - A mathematical model of a thermionic thermal protection system has been developed to study the characteristics of heat and mass transfer in a spatial, high-enthalpy air flow...     

Mathematical Simulation of the Supersonic Gas Flow Over a Wedge with an Attached Shock Wave and High-Temperature Effects

Journal of Engineering Physics and Thermophysics - The development of a supersonic gas flow over a wedge in the process of interaction of a plane shock wave with the wedge was mathematically...     

Effect of the Temperature Drop between the Isothermic Walls of a Channel on the Structure of Supersonic Flow and on the Aerodynamic Properties

The results of numerical analysis of the two-dimensional Navier–Stokes equations are used to investigate a supersonic flow of a perfect gas in a symmetric plane channel of variable cross section at the Mach number of M= 4 at the inlet for the Reynolds numbers in the range Re = 10³–10⁶. The top and bottom channel walls are assumed to be isothermic with different values of the temperature factor. It is shown that the asymmetry of the boundary conditions for temperature leads to the asymmetry of the entire flow field.     

竖直通道内降膜流动数值模拟

降膜蒸发是一种高效的传热技术,平均液膜厚度是考察降膜蒸发传热性能的一个重要影响因素。本文基于VOF算法,建立了水和空气沿二维竖直通道降膜流动的CFD模型,模拟研究了液膜速度、工质种类、同向和逆向气流对平均液膜厚度的影响。结果表明：提高液膜速度会增大平均液膜厚度;气相工质对液膜厚度影响不大,而液相工质对液膜厚度影响较大,液膜厚度随液相黏度增大而增大;同向气流对入口段和发展段的液膜厚度影响不大,稳定段液膜厚度会随着同向气流速度的增大而减小;平均液膜厚度随逆向气流速度增大而降低,当逆向气流速度达到2.5 m/s后,气流速度对液膜厚度的影响减小。     

矩形换热通道流动与强化换热特性数值模拟研究

采用切应力输运湍流模型(SST k-ω)分别对光滑矩形通道、连续肋矩形通道和间断肋矩形通道在五种典型工况下的流动换热进行了三维数值模拟研究。结果表明,基于SST k-ω湍流模型的光滑矩形通道流动阻力和换热系数模拟结果与经验公式计算结果可以较好符合,验证了本文所采用的数学模型的预测能力。在本文所研究的雷诺数(Re=8000~15000)范围内,连续肋和间断肋通道阻力较光滑通道都相应增加,连续肋片通道较光滑通道阻力增加2倍以上,间断肋片通道较光滑矩形通道阻力增加4.8倍以上,且随Re的增大而增加,同时,连续肋换热能力较光滑通道提升1.1倍以上,而间断肋较光滑通道换热能力提升约1.7倍以上。通过采用综合热学性能参数,对强化传热和阻力减小这两个因素进行评估,分析表明间断肋的综合热学性能明显优于连续肋。     

超音速流中结构非线性二元机翼的复杂响应研究

基于活塞理论计算作用在二元机翼上的气动力，采用拉格朗日方程建立系统的运动微分方程。通过平衡点的Jacobi矩阵的特征方程求出了系统的Hopf分叉点，研究了带有立方非线性俯仰刚度二自由度机翼系统在典型参数下的稳定极限环颤振和混沌响应。结果表明，在超过一定的流体速度后，系统平衡点的个数及稳定性均发生了变化；随着流速的增大，在积分初始值较小时，系统出现混沌等极为复杂的响应。