Three-Dimensional Interaction of a Blunt Cone with a Hot Region in a Supersonic Flow in the Presence of Surface Injection

The problem of the interaction of a blunt cone placed at zero incidence in a supersonic flow with a spherical hot region in the incident flow is considered for the case in which the hot region center is displaced relative to the axis of symmetry of the body. Two cases are studied: (1) the interaction of temperature inhomogeneity with an impermeable conical surface and (2) interaction in the presence of intense surface injection localized on the spherical bluntness of the body. It is shown that strong surface injection considerably improves the flow pattern and the aerodynamic characteristics of the body.     

Effect of a Dispersed Admixture on the Flow Pattern and Heat Transfer in a Supersonic Dusty-Gas Flow Around a Cylinder

A mathematical model of two-phase (gas-solid particle) flow which takes into account particle-particle collisions and the feedback effect of the admixture on the gas parameters is proposed. The dispersed phase is described by a kinetic equation of the Boltzmann type and the carrier gas by modified Navier-Stokes equations. Using this model, a supersonic uniform dusty-gas flow past a cylinder is calculated. The fields of the macroparameters of the admixture and the carrier medium are obtained. The dependence of the heat transfer at the stagnation point on the relative particle size and the free-stream admixture concentration is studied in detail. The ranges of these parameters on which particle collisions and the feedback effect of the admixture on the carrier-gas flow are important are found.     

Numerical Simulation of a Supersonic Flow with Transverse Injection of Jets

A plane supersonic flow with symmetric perpendicular injection of jets through slots in the walls is numerically simulated with the use of Navier–Stokes equations. The effect of the jet pressure ratio and Mach number on the flow structure is considered. The angle of inclination of the shock wave and the separationregion length are found as functions of the jet pressure ratio. The influence of the jet pressure ratio on the increase in the lift force arising owing to interaction of the flow with the injected jet is found.     

Determining the Optimal Contour of a Three-Dimensional Supersonic Jet Engine Outlet System

The problem of determining the optimal contour of a two-dimensional jet engine outlet system was solved in [1] using the direct method of the calculus of variations. In this study the method is developed for designing the optimal contour of a three-dimensional outlet system providing maximum thrust in a given direction.     

Direct Monte Carlo Simulation of Transverse Supersonic Rarefied Gas Flow around a Cylinder

Supersonic flow around a cylinder is investigated using the direct simulation Monte Carlo method over a wide rarefaction range: from the Knudsen number Kn = 0.1 to free-molecular flow. The effect of the cylinder temperature on the region of sharp nonequilibrium near the cylinder and the heat flux is studied.     

Calculation of the Flow Pattern and the Heat Fluxes in the Interaction of a Shock Wave with a Cylinder in a Supersonic Flow

The problem of determining the mechanical and thermal action on a cylinder in a supersonic flow with account for the interference between an incident shock and the detached bow shock has been studied extensively, both experimentally and theoretically, in the last few decades [1–12]. A fairly complete survey can be found in monograph [12]. The interest in the problem is mainly due to the fact that in this case the so-called fourth type of shock interaction can occur, leading to a sharp local increase in the mechanical and thermal loads. As for the problem of the interference flow past a cylinder itself, it can serve as a model problem for testing techniques of calculating the separation flow past the controls of hypersonic flight vehicles.In this paper, we attempt to demonstrate the possibility of using a fairly simple approach to the calculation of the above-mentioned flows, including those with a separation zone. The approach is based on a combination of numerical simulation within the framework of the inviscid gas model and subsequent calculation of the heat transfer parameters and does not require an excessive amount of computing power.     

Formation of Supersonic Zones and Local Separation Zones in Transonic Steady-State Flow Past Surface Roughness in the Free Interaction Regime

Within the framework of free interaction theory numerical methods are used to investigate the occurrence of supersonic zones with shocks in the outer inviscid region for flow past roughness in the lower viscous sublayer, with and without the formation of local separation zones.     

Theory of unsteady separation in supersonic flow around a convex corner

A theory of unsteady separation in inviscid supersonic flow around a convex corner is developed. Within the framework of the hypothesis suggested the mechanism of separationless-to-separated flow transition is explained and the forces leading to flow separation are determined as functions of the angle θ and the oncoming flow velocity. The values of the angle θ _k at which the flow is separated from the corner vertex and the stall angle θ _s determining the separated flow direction obtained previously in experiments and by numerical simulation are confirmed.     

关于超音速流中运动激波若干问题的研究

研究了在无粘完全气体流中的运动激波 ,讨论了激波运动速度D和来流速度U对激波后气流参数的影响 ,包括对激波后的总焓比值和总压比值以及对流转角的影响。计算结果表明它们不同于通常静止激波下所得到的结果。该内容涉及到超音速射流与障碍物或空腔体相互作用时出现的失稳状态下激波的振动和空腔体底部的反常加热问题。     

Numerical Studies on the Mixing of CH4 and Kerosene Injected into a Supersonic Flow with H2 Pilot Injection

Two-fluid model and divisional computation techniques were used. The multi-species gas fully N-S equations were solved by upwind TVD scheme. Liquid phase equations were solved by NND scheme. The phases-interaction ODE equations were solved by 2nd Runge-Kutta approach. The favorable agreement is obtained between computational results and PLIF experimental results of iodized air injected into a supersonic flow. Then, the numerical studies were carried out on the mixing of CH ₄ and kerosene injected into a supersonic flow with H ₂ pilot injection. The results indicate that the penetration of kerosene approaches maximum when it is injected from the second injector. But the kerosene is less diffused compared with the gas fuels. The free droplet region appears in the flow field. The mixing mechanism of CH ₄ with H ₂ pilot injection is different from that of kerosene. In the staged duct, H ₂ can be entrained into both recirculation zones produced by the step and injectors. But CH ₄ can only be carried into the recirculation between the injectors. Therefore, initiations of H ₂ and CH ₄ can occur in those regions. The staged duct is better in enhancing mixing and initiation with H ₂ pilot flame.     

Tollmien-Schlichting Waves in a Hypersonic Boundary Layer Flow in the Neighborhood of a Cooled Surface

A nonlinear time-dependent model of the development of longwave perturbations in a hypersonic boundary layer flow in the neighborhood of a cooled surface is constructed. The pressure in the flow is assumed to be induced the combined variation of the thicknesses of the near-wall and main parts of the boundary layer. Numerical and analytic solutions are obtained in the linear approximation. It is shown that if the main part of the boundary layer is subsonic as a whole, its action reduces the perturbation damping upstream and the perturbation growth downstream, while a supersonic, as a whole, main part of the boundary layer creates the opposite effects. An analysis of the solutions obtained makes it possible to conclude that the asymptotic model proposed can describe the three-dimensional instability of the Tollmien-Schlichting waves.     

Direct Statistical Simulation of a Supersonic Flow of a Binary Mixture of Rarefied Gases around a Transversely Positioned Cylinder

A supersonic flow of a binary mixture of gases in a wide range of rarefaction (from a flow with a Knudsen number K _n = 0.1 to a free-molecular flow) around a cylinder is studied by means of direct statistical Monte Carlo simulations (DSMC method). The influence of a small fraction of heavy particles in a light gas flow on the region of significant nonequilibrium near the cylinder and on the heat flux is considered.__________Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 46, No. 5, pp. 53–59, September–October, 2005.     

一种新的运动激波--非定常边界层相互干扰现象

本文探讨了一种新的激波－非定常边界层相互干扰现象，这种激波－边界层干扰现象既不同于定常激波－边界层干扰现象，又不同于激波在端面反射后与该激波所诱导的边界层之间的干扰现象，而是运动激波与稀疏波和第一激波所诱导的非这常边界层之间的干扰现象，本文对这种现象用微波动力学理论进行分析，并把这种干扰现象看成激波的绕射现象，同时在稀疏波破膜的双驱动激波管中进行实验观察，最后把理论分析与实验观察进行了比较。     

Evolution of Artificial Perturbations in the Boundary Layer on a Plate and in Its Wake at Supersonic Free-Stream Velocity

The evolution of artificial perturbations in the boundary layer on the flat section of a plate, on the backward-facing wedge behind the rarefaction wave fan, and in the wake is studied experimentally at the Mach number M=2.     

Investigation of a Gas Flow with Solid Particles in a Supersonic Nozzle

A two-phase flow with high Reynolds numbers in the subsonic, transonic, and supersonic parts of the nozzle is considered within the framework of the Prandtl model, i.e., the flow is divided into an inviscid core and a thin boundary layer. Mutual influence of the gas and solid particles is taken into account. The Euler equations are solved for the gas in the flow core, and the boundary-layer equations are used in the near-wall region. The particle motion in the inviscid region is described by the Lagrangian approach, and trajectories and temperatures of particle packets are tracked. The behavior of particles in the boundary layer is described by the Euler equations for volume-averaged parameters of particles. The computed particle-velocity distributions are compared with experiments in a plane nozzle. It is noted that particles inserted in the subsonic part of the nozzle are focused at the nozzle centerline, which leads to substantial flow deceleration in the supersonic part of the nozzle. The effect of various boundary conditions for the flow of particles in the inviscid region is considered. For an axisymmetric nozzle, the influence of the contour of the subsonic part of the nozzle, the loading ratio, and the particle diameter on the particle-flow parameters in the inviscid region and in the boundary layer is studied. __________ Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 46, No. 6, pp. 65–77, November–December, 2005.     

Evolution of the Flow Field around a Circular Cylinder and a Sphere upon Instantaneous Start with a Supersonic Velocity

Evolution of the flow field around a circular cylinder and a sphere instantaneously starting with a constant supersonic velocity (M = 5 and Re = 10⁵) from the state at rest is studied by means of numerical integration of unsteady twodimensional Navier–Stokes equations.     

Models of the Interaction between a Laminar Boundary Layer and a Transonic Flow

Possible regimes of viscous-inviscid interaction at transonic external flow velocities are investigated. It is shown that different flow regimes can exist depending on the relation between such parameters as the disturbance amplitude and the Mach and Reynolds numbers. Corresponding mathematical models are formulated and the solutions of some problems describing linear regimes of disturbance development are obtained. The models developed make it possible to describe all the possible interaction regimes.     

Study of the Effect of the Depth of the Cavity of a Braking Device on the Aerodynamic Drag of a Model in Transonic and Supersonic Flow

The flowfield and the aerodynamic drag of a model consisting of a pair of bodies (leading body a cylinder and trailing body a hollow cylinder) connected by a cylindrical bar along the axis of symmetry is experimentally investigated at Mach numbers ranging from 0.6 to 1.7. In the course of the experiments, the trailing body cavity depth and the connecting bar length were varied.__________Translated from Izvestiya Rossiiskoi Academii Nauk, Mekhanika Zhidkosti i Gaza, No. 2, 2005, pp. 186–192.Original Russian Text Copyright © 2005 by Pilyugin and Khlebnikov.     

湍流的诱导及其对瓦斯爆炸过程中火焰和爆炸波的作用

在实验的基础上,研究了管内瓦斯爆炸过程中湍流的诱导及其对瓦斯爆炸过程中火焰和爆炸波的影响作用.研究结果表明,管道面积突变对瓦斯爆炸过程中湍流的产生具有重要影响.管道面积突变(变大、变小)时,产生附加湍流,并使下游火焰气流的湍流度增加,瓦斯爆炸过程中火焰的传播速度迅速提高,并可诱导激波的产生.在80×80mm等截面直管中(瓦斯浓度为理论上最猛烈的爆炸浓度9.5%),瓦斯爆炸最大火焰传播速度为40.8m/s,管内各点均为压力波信号,当管道加装一Φ300mm圆管形成面积突扩11倍和突缩11倍两断面后,面积突扩处(L/D=22)火焰速度增大5.05倍,达到64.4m/s,面积突缩处(L/D=28)火焰速度为156.0m/s, 增大4.55倍,并在L/D=48倍处形成激波(超压1.6976atm、波速416.7m/s),在L/D=98倍处,激波强度最大.在面积突变管内加装加速环可使瓦斯爆炸过程中湍流度加剧,火焰的传播速度更高,激波生成的位置(L/D=28)、最强点位置(L/D=70)均前移,激波强度增大.研究结果对指导现场如何防治瓦斯爆炸,减轻瓦斯爆炸的威力具有一定的指导意义.     

Distinctive Features of the Lateral Flow for a Convergent Air-Intake with a Convergent Nose Compression Surface

The results of numerical and experimental studies of a model configuration of a hypersonic vehicle realizing the principle of compression convergence of the entire jet captured by an air-intake from the oncoming stream are presented. The external flow past a convergent air-intake integrated with a transversely-concave nose compression surface is investigated over the freestream Mach number range from 2 to 6. The salient features of the flow pattern near air-intakes with sidewalls of different length are established and the influence of a limitation on the lateral flow near the external compression wedge on the flow rate characteristics of the air-intake is established. The numerical calculations are performed within the framework of the inviscid gas model using higher-order TVD schemes; the calculated and experimental results are compared.