Investigation of regions of unbounded growth of the particle concentration in disperse flows

Осипцов, А. Н.

doi:10.1007/bf01093900

Cited by 49 publications

(39 citation statements)

References 2 publications

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“…The concentration singularity found for the first and second regimes is integrable (Osiptsov, 1984). It means that the average distance between the particles is still much greater than the particle radius, and the dilute-suspension model remains valid over the entire flow.…”

Section: Particle Trajectories Velocity and Concentration Fieldsmentioning

confidence: 96%

Migration of settling particles in a horizontal viscous flow through a vertical slot with porous walls

Лебедева

Asmolov

2011

International Journal of Multiphase Flow

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Section: Particle Trajectories Velocity and Concentration Fieldsmentioning

confidence: 96%

Migration of settling particles in a horizontal viscous flow through a vertical slot with porous walls

Лебедева

Asmolov

2011

International Journal of Multiphase Flow

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“…An asymptotic analysis of the behavior of the dispersed-phase parameters in the neighborhood of a potential-flow stagnation point [ 16] indicated that in the exact steady-state solution the singularity of n8 has the type n~ ~ 1/y r where r varies over the range 0 < r < 2 -V~ (plane flow) or 0 < r < 3 -~ (axisymmetric flow). The concentration singularity is integrable and hence the mean distance between the particles remains finite and the model of noncolliding particles is still valid [16].…”

Section: Z~ (R Xo)mentioning

confidence: 99%

“…The concentration singularity is integrable and hence the mean distance between the particles remains finite and the model of noncolliding particles is still valid [16]. The analysis and the calculations carried out by Osiptsov and Shapiro [15] We will now determine the near-wail asymptotics of the particle concentration for the nonstationary problem on the symmetry axis.…”

Section: Z~ (R Xo)mentioning

confidence: 99%

Non-stationary effects in hypersonic nonuniform dusty-gas flow past a blunt body

1999

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In the framework of the two-fluid model, a hypersonic flow of a nonuniform dusty gas with low inertial (non-depositing) particles around a blunt body is considered. The particle mass concentration is assumed to be small, so that the effect of particles on the carrier phase is significant only inside the boundary layer where the particles accumulate. Stepshaped and harmonic nonuniformities of the particle concentratinn ahead of the bow shock wave are considered and the corresponding nonstationary distributions of the particle concentration in the shock layer are studied. On the basis of numerical study of nonstationary two-phase boundary layer equations derived by the matched asymptotic expansion method, the effects of free-stream particle concentration nonuniformities on the thermal flux and the friction coefficient in the neighborhood of stagnation point are investigated, in particular, the most "dangerous" nonuniformity periods are found.

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“…The envelope surface of the trajectories of particles reflected from the walls is a caustics with the volume fraction of particles formally tending to infinity. As was shown in [15], though the volume fraction of particles on the caustics proper becomes infinite, the mean volume fraction of particles in an arbitrary vicinity of the caustics of this type is finite. Actually, this means that the mean volume fraction of particles in each cell of the grid used to solve the carrier gas equations numerically is (even formally) a finite quantity.…”

mentioning

confidence: 92%

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

Verevkin

Tsirkunov

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...

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Investigation of regions of unbounded growth of the particle concentration in disperse flows

Cited by 49 publications

References 2 publications

Migration of settling particles in a horizontal viscous flow through a vertical slot with porous walls

Migration of settling particles in a horizontal viscous flow through a vertical slot with porous walls

Non-stationary effects in hypersonic nonuniform dusty-gas flow past a blunt body

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

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