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To study the characteristics of the mass transfer of noncondensable gases in the primary loop of the nuclear icebreaker reactors, models of the core and the up-core space were developed using the Relap5 (USA) and Fluent (USA) codes and modeling of interphase mass transfer and transport of the gas phase by the water coolant was performed on these sections. Spatial non-uniformity of the content of undissolved gases, which arises as a result of vapor-gas bubbles concentrating in the vortex structures of the flow and resulting in a significant reduction of their dissolution rate, was revealed. This must be taken into account in the analysis of the operation of the primary loop equipment of nuclear icebreakers (hydrogen absorption in the titanium alloys of steam-generator piping, nodular corrosion of the zirconium cladding of the fuel rods).

A method is proposed for approximate solution of the problem on the hydrodynamics of the evaporating meniscus of a thin liquid film on a heating surface. This method is based on reduction of the initial differential equation for the hydrodynamics of the meniscus. The interaction of the intermolecular, capillary, and viscous forces and the molecular-kinetic effects at the boundary between the meniscus and the adsorbed thin liquid film were analyzed. The analytical solution obtained allows one to determine the geometrical parameters of such a meniscus and the heat flow through it.

The problem on the growth of a vapor bubble in a liquid whose superheating enthalpy exceeds the phase transition heat has been considered. A physical model of the “pressure blocking” in the bubble is presented. The problem for the conditions of the experiment on the effervescence of a butane drop has been solved numerically. An algorithm for constructing an analytical solution of the problem on the bubble growth in a highly superheated liquid is proposed.

An approximate kinetic analysis of the process of intense evaporation has been carried out. The analytical solutions obtained for temperatures, pressures, and mass velocities of vapor agree well with the available numerical and analytical solutions. The evaporation limiting mass velocity has been calculated.

The problem of bubble pulsations in a volume of a quiescent liquid with periodic external pressure fluctuations has been considered in a linear approximation. The incorrectness of the use of a polytropic approximation is shown. An approximate analytical solution for the resonance frequency of pulsations has been obtained.

The derivation of the generalized Rayleigh equation that describes the dynamics of a spherical gas bubble in a tube filled with an ideal liquid is given. Its solution has spherical (the classical Rayleigh equation) and cylindrical (the case of a long tube) asymptotics. An exact analytical solution of the problem on vapor bubble collapse in a long tube has been obtained.

A generalized inertial thermal model for the vapor bubble growth in an infinite volume of uniformly superheated liquid is developed. An approximate analytical solution to the problem is obtained. The solution provides exact asymptotic limiting processes over all defining problem parameters. The physically correct description of experimental data related to vapor bubble growth in the near-spinodal region, which were previously considered as paradoxical, is presented for the first time.

A universal analytical solution of the problem on heat input-controlled growth of a vapor bubble in a large volume of uniformly superheated liquid is obtained for the first time. The derived final formula provides for the desired limiting transitions and agrees well with the numerical results of Scriven for the entire possible range of variation of the determining parameters. It is demonstrated that the radial flow of liquid through the interface intensifies the heat input, which brings about an increase in the rate of bubble growth. The results of analysis lead one to conclude that none of the known particular solutions is capable of correctly describing the dependence of the modulus of the bubble growth rate on Jakob's number and on the density ratio of the phases.

A generalized inertial thermal scheme is developed of vapor bubble growth in an unrestricted volume of superheated liquid. An approximate analytical solution is obtained, which provides for limiting processes in asymptotic curves for all determining parameters of the problem. A physically correct description is obtained for the first time of available “paradoxical” experimental results in vapor bubble growth in the spinodal region.

A pulsation model is suggested for the detachment of a vapor bubble that is growing on a solid wall according to a prescribed law.

This work presents a proof of the inequality that determines the relation between two values of the heat-transfer coefficient averaged by different procedures in processes of heat exchange with periodic intensity.

An approximate analytical solution of the problem of thermohydraulic stability of a homogeneous two-phase flow is obtained with allowance for the effect of the channel-wall thickness.

The process of formation of a droplet in a liquid-filled cavity that is a printing element of a jet printer is studied on the basis of an approach developed earlier.

A previously developed method of analysis of the processes of heat transfer with periodic intensity is generalized to the case of simultaneous fluctuations of the temperatures of the wall and the liquid. A final expression for the dependence of the coefficient of conjugation on the generalized parameter of the problem is obtained.

The limit of the stability of a heat carrier flow against small “density wave”-type perturbations is found. It is shown that stabilization of flow sets in on increase in the volume heat capacity and also in the amplitude of the heat-transfer coefficient fluctuations.

A method for solving a conjugate periodic convective-conductive problem for a "heat-transfer agent-wall" developed earlier system is used for calculation of the effect of the wall parameters on heat transfer under conditions of jet wetting.

A relation for the critical heat flux density in liquid boiling under conditions of natural convection is derived by means of a previously obtained approximate analytical solution of the problem of the hydrodynamics of an evaporating meniscus.

The velocity of the phase drift in a vertical bubble flow is calculated approximately on the basis of a method developed earlier.

Using an approximate method of analysis developed earlier for studying heat-exchange processes occurring with a periodic intensity, the problem of periodic evaporation of a liquid film from the surface of a heat-transfer wall is considered.

On the basis of an approximate analysis of flow in a liquid macrofilm on a heating surface the characteristics of nucleate boiling (surface density of nucleation sites, effect of the thermal conductivity of the wall on the averaged heat transfer) are estimated.

Using an analog of a Rayleigh equation the limiting law of vapor-bubble growth in a tube in coolant boiling in the region of very low pressures is obtained.

Processes of heat transfer with periodically varying intensity on the surface of heated bodies of three typical geometries (plate, cylinder, sphere) are considered. The true heat transfer coefficient, which varies in time by the law of a periodic step function having two free parameters - amplitude and asymmetry, is specified on the heat transfer surface. Resultant relations are obtained for calculating the experimental heat transfer coefficient, which is the quantity measured in a traditional heat transfer experiment and used in applied calculations.

The problem of determining the rate of rise of large gas bubbles in an infinite volume and a vertical tube is considered. In the first case the shape of the bubble is constructed by “gluing together” the front surface immersed in a flow of ideal liquid and the rear surface being formed under the action of gravitational and capillary forces, and in the second case the solution of the Laplace equation is constructed for the velocity potential in the problem of ideal liquid flow in a tube around a semiinfinite cylindrical body with a hemispherical frontal part.

Analysis is made of the growth of a vapor (gas) bubble in a horizontal tube filled with an ideal liquid.

On the basis of model representations developed earlier the author has obtained an analytical solution of the problem of vapor bubble growth on a wall in an underheated liquid.

A simple method for calculation of heat transfer in transient boiling of liquids on a wall with a finite “coefficient of thermal activity≓ is suggested on the basis of model concepts available in the literature and also by an earlier developed method for analysis of processes.