V. Sh. Shagapov

Structure of shock waves in a liquid containing gas bubbles

The structure of a stationary shock wave in a liquid containing gas bubbles is investigated theoretically. For the description of such a two-phase mixture the two-velocity two-temperature model with two pressures is used [1], taking into consideration the small-scale frictions, the noncoincidence of the velocities, temperatures, and pressures of the phases, and the oscillations of the bubbles. The existence of shock waves having a discontinuity surface in front as well as of shock waves with continuous structure is shown. It is shown that unlike the two-phase mixtures of gas with drops or particles where the structure of the wave depends mainly on the interphase friction, in two-phase mixtures of a liquid with bubbles the behavior of the wave and its structure depends essentially on the interphase heat transfer. Wave characteristics, such as the wavelength of the pulsations, their damping decrement, do not have a monotonic dependence on the parameters governing the intensity of heat transfer and do not lie between the corresponding values for isothermic and adiabatic regimes of behavior of the bubbles. Shock waves in liquids with gas bubbles were investigated theoretically and experimentally in [3–7]. A detailed review of the work up to 1971 is given in [8].

Dynamics of detonation waves in an annular layer of a round pipe

The dynamics of axisymmetric detonation waves in a round pipe containing an annular near-wall bubble layer with a combustible gaseous mixture are studied. The situations in which within the annular layer there are a pure liquid or a bubbly mixture with an inert (unexplosive) gas are considered.

Two-Dimensional Pressure Waves in a Fluid with Bubbles

The specific features of wave evolution in a fluid with a finite bubble zone are studied. The two-dimensional effects are taken into account. The results for two-dimensional wave evolution in a uniform bubbly fluid are also presented.

Damping of solitons in bubble media

The author considers the problem of damping of solitons in a bubble medium because of viscosity and interphase heat and mass transfer nonequilibrium on the assumption that their evolution is described by successive interchange of steady soliton solutions. The changes in the amplitude of the solitons obtained from analytical expressions are compared with the available experimental data.

Oscillations of a gas-vapor bubble in an acoustic field

It is shown that at large vapor contents, as a result of the combined action of phase transitions and capillary effects, the small radially symmetric oscillations of gas-vapor bubbles in an acoustic field are unstable in amplitude. The critical vapor concentration in the bubble separating regions of qualitatively different bubble behavior in the acoustic field is determined. Expressions are obtained for the decay rate of the radial oscillations of the gas-vapor bubble and the growth rate characterizing the rate of increase of oscillation amplitude in the region of instability. It is shown that adding only a slight amount of gas to the vapor bubble leads to a marked decrease in the growth rate. It is found that in the particular case of a vapor bubble the tine growth rate characterizing the development of the instability is of the same order as the second resonance frequency of the vapor bubble. This may serve to explain why in the case of vapor bubble oscillations the second resonance effect, which has been established in a number of theoretical studies and is widely discussed in the literature, has not yet been experimentally confirmed. The problem of spherically symmetrical processes around gasvapor bubbles was posed in [1], and their small oscillations are investigated in detail in [2–4].

Towards the problem of droplet injection in a vapor with the aim of reducing the pressure

As applied to the analysis of sprinkler systems which inject droplets into a vapor in the case of emergency pressure increases, the process of vapor condensation on a single droplet is considered. For the specification of the intensity of interphase heat and mass transfer, the solution of an unsteady heat conduction problem is used. Approximate formulas describing the laws of the pressure drop in a vapor-droplet system due to the condensation of the vapor phase are obtained.

Motion of a discharge containing water condensate in the bottom layer of the atmosphere

The propagation of a one-off discharge containing water vapor and condensate in the atmosphere is considered in the three-dimensional formulation. The process is accompanied by mixing with the surrounding air and phase transitions. The evolution of the flow, concentration, and temperature fields is studied as a function of the initial discharge parameters (temperature and moisture content) and the surrounding air parameters.

Some characteristics of the propagation of sound in binary bubble media

The effect of the composition and thermophysical properties of binary vapor-liquid bubble systems on the propagation characteristics of small disturbances, the stability of the media and the rate of development of instability is investigated.

Gas solubility effects associated with the propagation of small perturbations in bubbly mixtures

The effect of gas solubility on the oscillation characteristics of bubbles in an acoustic field, the propagation and damping of perturbations in bubbly mixtures and, moreover, the stability of such media is analyzed.

Allowance for nonstationary heat and mass transfer in the propagation of small perturbations in a liquid with bubbles

The propagation of small perturbations in a liquid with vapor-gas bubbles is studied. Heat and mass transfer between the phases is taken into account on the basis of the exact equations of heat conduction and diffusion. The aim of the present investigation is to make more precise the results of an earlier paper [1] of the author and verify the applicability of using fixed coefficients of heat and mass transfer for nonstationary heat and mass transfer between a pulsating bubble and the liquid.