A. F. Polyakov

Effect of particle concentration on fluctuating velocity of the disperse phase for turbulent pipe flow

We present the results of an experimental investigation of the fluctuation velocity distributions of solid particles when they move in the downward gas turbulent pipe flow. The glass particles (Stk L ≃ 1) having an average diameter of 50 μm were used as a disperse phase. The average particle mass concentration varied within the range of M = 0 to 1.2. The results obtained showed the particle fluctuation velocity to be strongly dependent on their mass loading. There has been observed an influence of the particle concentration on the significant increasing of their axial fluctuation velocity in the pipe wall region

Numerical simulation of temperature stratification in an accumulation-type solar water-heating installation

Numerical study of nonstationary three-dimensional laminar convection is performed in the model of the main element of a solar water-heating installation of the accumulation type in the process of a daily cycle of heat supply. Three-dimensional velocity fields and peculiarities of temperature distributions in the tubular element of installation that are connected with formation of temperature stratification are analyzed at different angles of the element inclination to the horizon.

Free convection and heat transfer in a near-supercritical fluid in a horizontal square cavity with lateral heating

The problem of natural convection and heat transfer of water is solved numerically under a pressure of 23 MPa near the critical isochore, in a square cavity with lateral heating. It is shown that natural convection under near-supercritical state of the liquid is implemented in microchannels and under conditions of microgravity. The data on heat transfer are generalized.

An experimental investigation of the behavior of solid particles during their motion in smooth and dimpled pipes

Results are given of LDA measurements of averaged and fluctuation velocities of glass particles during their deposition in smooth and dimpled narrow pipes. Experiments reveal a decrease in the axial component of averaged velocity of particles and a significant increase in fluctuation velocities of particles during their motion in a pipe with dimples.

Experimental study of fluctuations of particle velocity in a turbulent flow of air in a pipe

The distribution of longitudinal and normal components of the fluctuation velocity of particles in their motion in a downward turbulent airflow in a pipe is obtained. The effect of the concentration of particles on the intensity of fluctuations of their velocity is studied. A high rise of the longitudinal fluctuation of the velocity of particles in the pipe wall region with an increase in their concentration is revealed.

A steady viscous-thermogravitational flow of capillary liquid and heat transfer in a vertical cavity under asymmetric heat conditions

The problem of joint forced and free laminar convection and heat transfer for liquid with a variable viscosity under a linear temperature distribution between surfaces of a vertical two-dimensional channel is solved analytically. The dependences obtained manifest a strong difference (upon a relatively small variation in viscosity) of the distributions of velocity, friction drag coefficient, and heat transfer from the case of the full Boussinesq approximation while solving problems of mixed convection.

Generalization of experimental data on heat transfer in permeable shells made of porous reticular materials

Heat transfer from six samples of porous reticular material to cooling gas (air) at small Reynolds numbers is experimentally studied. The specific features pertinent to heat transfer essentially affected by longitudinal heat conductivity along gas flow are analyzed. The experimental results are generalized in the form of dimensionless empirical relations.

Heat transfer in envelopes made of porous network materials

Presented here are results of combined laboratory and numerical experiments on heat transfer in envelope porous network materials. It is shown that the discrepancies between the relationship for internal heat transfer and the experimental data on volumetric heat transfer at small Reynolds numbers are associated with the effect of heat conductivity along the cooling gas flow on the temperature field.

Laser Doppler Anemometer Measurement of Large-Particle Relative Concentrations

A standard laser Doppler anemometer can be used to measure the relative concentration of large particles in two ways: from the signal entry frequency and from the photomultiplier current. Test measurements on particle distributions are reported.

Numerical realization of viscous-thermogravity regimes in microchannels and under the microgravity conditions at near-critical liquid properties

Numerical investigation is performed of 3D laminar flow in tubes at supercritical liquid pressures within the near-critical parameter ranges with account for the buoyancy forces. Water is taken as the working medium. Thermophysical properties are presented in the form of interpolation dependencies. Data are obtained on the influence of strongly variable physical properties on the laminar flow in microchannels and under microgravity conditions. Peculiarities are analyzed of the single-phase liquid flows in the vertical and horizontal tubes at the near-critical parameters as compared to the data for constant physical properties.