Semiempirical model of impact interaction of a disperse impurity particle with a surface in a gas suspension flow

Progress in Propulsion Physics

Romanyuk

Panfilov

2011

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Time-dependent two-dimensional (2D) §ow of dusty gas through a set of two cascades of airfoils (blades) has been studied numerically. The ¦rst cascade was assumed to move (rotor) and the second one to be immovable (stator). Such a §ow can be considered, in some sense, as a §ow in the inlet stage of a turbomachine, for example, in the inlet compressor of an aircraft turbojet engine. Dust particle concentration was assumed to be very low, so that the interparticle collisions and the e¨ect of the dispersed phase on the carrier gas were negligible. Flow of the carrier gas was described by full Navier Stokes equations. In calculations of particle motion, the particles were considered as solid spheres. The particle drag force, transverse Magnus force, and damping torque were taken into account in the model of gas particle interaction. The impact interaction of particles with blades was considered as frictional and partly elastic. The e¨ects of particle size distribution and particle scattering in the course of particle blade collisions were investigated. Flow ¦elds of the carrier gas and §ow patterns of the particle phase were obtained and discussed.

Section: Results For the Particle Phasementioning

confidence: 99%

Section: Results For the Particle Phasementioning

confidence: 99%

Section: Modeling Of Particle-phase Flowmentioning

confidence: 99%

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Effects of particle mixing and scattering in the dusty gas flow through moving and stationary cascades of airfoils

Progress in Propulsion Physics

Romanyuk

Panfilov

2011

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“…If a particle crosses the exit cross section of the test section, it is excluded from further consideration. If a particle collides with the walls of the tunnel or the model, its rebound is considered as frictional and not completely elastic, and the semiempirical particle wall collision model developed in [14] is used for calculating the parameters of a particle just after its rebound. This model is based on the laws of mechanics and the experimental data [15] for the restitution coe©cients of the normal and tangential to the wall velocity components of the particle gravity center.…”

Section: Mathematical Model Of the Two-phase Flowmentioning

confidence: 99%

Numerical analysis of dusty gas flow in a hypersonic shock tunnel

Progress in Flight Physics

Verevkin

2013

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The results of a computational simulation of an unsteady two-phase gas particle §ow in a hypersonic shock tunnel with a convergent-divergent nozzle are described. In calculations, the con¦guration of the tunnel and the initial gas and particles£ parameters were taken the same as in experiments carried out at the Central AeroHydroDynamic Institute (TsAGI) (Russia). The designed Mach number at the nozzle exit is M = 6.01. Particles are injected into the high-pressure chamber of the shock tube just before the diaphragm opening. The carrier gas §ow is described by the Euler equations which are solved by a ¦nite-volume method of the second order. The particle-phase motion is simulated using the Lagrangian method. Developing in time a two-phase §ow is investigated from the instant of opening the diaphragm between the high-and low-pressure chambers of the shock tube to the end of the quasi-steady-state §ow over a model in the test section. Flow properties of both phases are discussed with emphasis on the problems that can appear in experiments.

“…If the particle collides with the walls of the shock-tunnel channel, nozzle, test section, or model, it is assumed to rebound. The parameters of the reflected particle at the rebound instant are determined by a semi-empirical model of particle-wall impact interaction [10], which yields the following relations for the normal-to-wall and tangential-to-wall components of the velocity vector of the center of mass of the particle v + pn and v + pτ and its angular velocity ω + p :…”

mentioning

confidence: 99%

Flow of a dispersed phase in the Laval nozzle and in the test section of a two-phase hypersonic shock tunnel

Verevkin

2008

J Appl Mech Tech Phy

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An unsteady gas-particle flow in a hypersonic shock tunnel is studied numerically. The study is performed in the period from the instant when the diaphragm between the high-pressure and lowpressure chambers is opened until the end of the transition to a quasi-steady flow in the test section. The dispersed phase concentration is extremely low, and the collisions between the particles and their effect on the carrier gas flow are ignored. The particle size is varied. The time evolution of the particle concentration in the test section is obtained. Patterns of the quasi-steady flow of the dispersed phase in the throat of the Laval nozzle and the flow around a model (sphere) are presented. Particle concentration and particle velocity lag profiles at the test-section entrance are obtained. The particle-phase flow structure and the time needed for it to reach a quasi-steady regime are found to depend substantially on the particle size.Key words: shock tunnel, Laval nozzle, two-phase gas-particle flow, flow around a body, numerical simulations.Introduction. Shock tunnels have been used for experimental research of aerodynamics and physical gasdynamics problems for more than half a century [1]. Comparatively recently, such shock tunnels have been used to study hypersonic dusty-gas flows. The results of research performed in a UT-1M experimental setup at the Central Hydroaerodynamic Institute (TsAGI) are the most well-known ones. A hypersonic two-phase shock tunnel is a classical shock tunnel with an attached hypersonic contoured nozzle generating a high-velocity flow in the test section connected at the end with a vacuum chamber. For a two-phase flow to be produced in the test section, dispersed particles are injected into the high-pressure chamber at the instant of wind-tunnel start-up; these particles are then entrained by the gas flow. The structure of the unsteady gas flow developing in such a shock tunnel after diaphragm opening was studied in detail in [3]. First, a strong shock wave is formed, which moves toward the nozzle. When this wave is reflected from the nozzle walls, transverse shock waves are formed. These waves interact with each other and with the nozzle walls both regularly and irregularly with formation of triple (Mach) configurations. As a result, two intense near-axis vortices come into being and develop in the nozzle throat; later on, these vortices are entrained downstream. At the initial stage, however, these vortices exert a significant effect on the behavior of the particle phase, in particular, on the motion of fine particles. Because of different inertial properties, fine and coarse particles behave differently in an unsteady flow in the nozzle and test section. Coarse particles lag behind the carrier gas, collide with the walls of the converging part of the Laval nozzle, and are reflected from the walls. This results in redistribution of particles in the transverse direction, and the two-phase flow in the test section may become substantially nonuniform. Moreover, because of the lag of the par...