Conjugate Problem Of Heat Exchange Research Articles

Validation of RANS Turbulence Models for the Conjugate Heat Exchange Problem

This paper addresses problems of mathematical modeling of heat exchange processes in the pre-nozzle volume of a solid propellant rocket engine with a charge with starlike cross-section and a recessed hinged nozzle. Methods of mathematical modeling are used to solve the quasi-stationary spatial conjugate problem of heat exchange. An analysis is made of the influence of RANS turbulence models on the flow structure in the flow channels of the engine and on the computed heat flow distributions over the surface of the recessed nozzle. Methods of mathematical modeling are used to solve the quasi-stationary spatial conjugate problem of heat exchange. Results of validation of RANS turbulence models are presented using well-known experimental data. A comparison of numerical and experimental distributions of the heat-transfer coefficient over the inlet surface of the recessed nozzle for the engine with a cylindrical channel charge is made for a primary choice of turbulence models providing a qualitative agreement between calculated and experimental data. By analyzing the results of numerical modeling of the conjugate problem of heat exchange in the combustion chamber of the solid propellant engine with a starlike channel, it is shown that the SST $k-\omega$ turbulence model provides local heat-transfer coefficient distributions that are particularly close to the experimental data.

Numerical Simulation of Intrachamber Processes in the Power Plant

This paper considers the issues of numerical modeling of nonstationary spatial gas dynamics in the pre-nozzle volume of the combustion chamber of a power plant with a cylindrical slot channel at the power plant of the mass supply surface. The numerical simulation for spatial objects is based on the solution conjugate problem of heat exchange by the control volume method in the open integrated platform for numerical simulation of continuum mechanics problems (openFoam). The calculation results for gas-dynamic and thermal processes in the power plant with a four-nozzle cover are presented. The analysis of gas-dynamic parameters and thermal flows near the nozzle cover, depending on the canal geometry, is given. The topological features of the flow structure and thermophysical parameters near the nozzle cap were studied. For the first time, the transformation of topological features of the flow structure in the pre-nozzle volume at changes in the mass channel’s geometry is revealed, described, and analyzed. The dependence of the Nusselt number in the central point of stagnation on the time of the power plants operation is revealed.

Problem of conjugate heat transfer between main gas pipeline and frozen ground

Mathematical model of non-isothermal gas flow within the framework of tube hydraulics including change of tube cross-section due to hydrate formation and the dependence of coefficient of heat transfer between gas and hydrate layer on varying flow area is proposed. The corresponding conjugate problem of heat exchange between imperfect gas in the pipeline and the environment is reduced to the solution of differential equations describing non-isothermal flow of gas in pipes and heat transfer equations in ground with the corresponding conjugation conditions. In the quasi-stationary mathematical model of hydrate formation (dissociation), the dependence of gas-hydrate transition temperature on gas pressure is taken into account. Some decisions taken in the design of the first section of the main gas pipeline «Power of Siberia» have been analyzed. It has been shown that if gas is not sufficiently dried, outlet pressure may drop below the technological limit in about 6-7 hours. At the same time, for completely dry gas ,it is possible to reduce the cost of thermal insulation of the pipeline at least two fold.

Alternative to mathematical models of gas production: numerical experiment

Computational experiment for comparison of quasi-one dimensional and two dimensional mathematical statements of the conjugate problem of heat exchange between gas producing well and the rocks has been carried out. The problem consists of solution of differential equations describing non-isothermal gas flow in the well and the heat conduction equation for surrounding rocks. The dependence of the coefficient of heat exchange of the gas with the hydrate layer on the time-varying flow area is taken into account in a quasi-stationary mathematical model of hydrates formation (dissociation) in gas well. The results of computational experiment correspond to two cases of production of wet and dry gas at the Otradninsky gas-condensate field.

Modeling the Formation of Hydrates in gas Wells in Their Thermal Interaction With Rocks

Consideration is given to a conjugate problem of heat exchange between the imperfect gas in a well and the environment (rocks). This problem is reduced to solution of differential equations describing nonisothermal gas fl ow in the well and the propagation of heat in the rocks. The dependence of the coeffi cient of heat exchange of the gas with the hydrate layer on the time-varying fl ow area is taken account of in aquasistationary mathematical model of formation (dissociation) of hydrates in the gas well. It is shown that in the conjugate formulation of the problem, the time of formation of hydrate plugs grows substantially in contrast to the case where the rock temperature is assumed to be constant.

Flip-chip structure transient thermal model

This paper describes new approach to transient thermal characterization of widely used flip-chip structures. The thermal model is based on the formalization of conjugate problem of heat exchange in the die and the substrate. Accepted provision on linearity of the decision function along the z coordinate allowed building the method characterized by simple programming and temperature calculation in any construction point regardless of previous values and partitioning mesh. The utilization of the mathematical model is illustrated by the example of thermal simulation in the test structure and approved by comparison with the results obtained by thermal–electrical technique.

Nonsteady conjugate heat exchange during liquid flow in coaxial channels

The article deals with conjugate nonsteady heat exchange in coaxial channels during stabilized flow of a viscous incompressible liquid. The problem of the velocity profiles of the liquid is solved by methods of integral transformations. The conjugate problem of heat exchange in coaxial channels is solved by the finite-element method.

Conjugate problem of heat exchange in steam condensation inside a horizontal cylinder

The conjugate problem of heat exchange is solved for the case of condensation of slowly moving saturated steam in a horizontal tube without the formation of a draining stream in its lower part.

Study of hydrodynamics and conjugate heat exchange on the stabilization section in the flow of a heat carrier in a bundle of finned tubes

A conjugate problem of heat exchange and hydrodynamics in a channel of complex shape is numerically solved.

The difference method of solving the conjugate problem of heat exchange during gas flow in a thick-walled channel between communicating vessels

An algorithm is developed for the numerical solution of a nonlinear system of differential equations describing the processes of gasdynamics and heat exchange during the transfer of gas from vessel to vessel through a flat, annular, or cylindrical channel with walls of finite thickness.