L. I. Zaichik

Hydrodynamics and heat transfer of turbulent gas suspension flows in tubes—1. Hydrodynamics

Abstract By the method of averaging over the ensemble of turbulent flow realizations, the averaged motion and mass balance equations for a solid phase and a flow as a whole are derived. Closed expressions for the second single-point moments of fluctuations of the solid and carrier characteristics are obtained in terms of correlations of the carrier phase velocity fluctuations in a non-homogeneous turbulent flow. Based on these expressions, a set of equations is written for the second single-point moments of the carrier phase velocity fluctuations in the presence of particles. Hydrodynamic analysis is presented for turbulent gas suspension flows in tubes. Comparison with experimental data shows a satisfactory description of the processes of momentum transfer by a particle-laden flow.

Hydrodynamics and heat transfer of turbulent gas suspension flows in tubes—2. Heat transfer

Abstract By the method of averaging over the ensemble of turbulent flow realizations, averaged heat transfer equations for a solid phase and a flow as a whole are derived. Closed expressions for the second single-point moments of the solid and carrier phase velocity and temperature fluctuations in terms of the second moments of the carrier phase velocity and temperature fluctuations in a non-uniform turbulent flow are found. Based on these expressions, a set of equations is written for the second single-point moments of the liquid phase velocity and temperature fluctuations in the presence of particles. Heat transfer calculations are carried out for turbulent flow of gas suspension in circular tubes. The effect of the relationship between the thermal and physical properties of the particle material and gas on the thermal characteristics of a two-phase flow is investigated. The predicted Nusselt numbers for a dusty flow agree satisfactorily with the experimental data.

Heat transfer in laminar plane channel flow with uniform suction or injection

Abstract Consideration is given to heat transfer in a developed laminar incompressible flow with constant physical properties in a two-dimensional channel with porous walls having constant temperature. Several asymptotic solutions of the energy equation for small and large wall Peclet numbers and large Prandtl numbers are obtained. The computed results of the local Nusselt number distribution in both the thermal stabilization and channel entrance regions are generalized for all Prandtl numbers by a single relation in the form of the relative heat transfer law.

Influence of particles on the turbulent heat-transfer intensity

The influence of particles on the intensity of turbulent heat transfer by a gas-suspension is investigated on the basis of a system of equations of the second single-point moments of the carrier phase velocity and temperature fluctuations.

Stability of the free-convection boundary layer on a vertical permeable plate

The hydrodynamic stability of flow in a free-convection boundary layer on a permeable plate is numerically investigated. The effect of the plate nonisothermicity and the injection blowing intensity on the critical parameters is determined.

Flow stability in a plane-parallel channel with one permeable wall

We have calculated the characteristics of neutral flow stability in a plane-parallel channel with injection or suction through a permeable wall.

Heat exchange in tubes with permeable walls in the presence of internal heat sources

Solutions are obtained for the energy equation for fluid flow in tubes with uniform injection of suction and heat sources in the stream.

Flow and heat transfer of finely dispersed turbulent flows in channels

Equations for the second moments of the velocity and temperature fluctuations are used to study the effect of particles on the rate of turbulent momentum and heat transfer in the flow of a gas suspension in circular pipes.

Effect of variability of physical properties on heat transfer in the turbulent pipe flow of gases

The effect of variability of physical properties on heat transfer in the turbulent flow of different gases is studied on the basis of the limiting heat-transfer law.

Stability of the laminar boundary layer with strong blowing

The authors present a method of calculating nonsimilarity laminar boundary layer flow over a permeable flat plate with uniform blowing.