Modelling the Temperature State of Bodies with Internal Heat Sources

This article presents the results of the development of a numerical - analytical method for solving the problem of thermal conductivity in a plate fuel element. An unsteady temperature field inside a fuel element is investigated for a given spatial distribution of heat sources. The heat release rate is given by the quadratic function of the coordinate. Modeling the temperature state of bodies with internal heat sources allows you to study the operation of equipment in transient modes, control heating/cooling modes of elements, determine temperature stresses, etc. It is shown in the work that regardless of the power of internal sources of heat, the temperature state is stabilized at a temperature level that depends on the Pomerantsev number.

Internal Resonance of Hyperelastic Thin-Walled Cylindrical Shells under Harmonic Axial Excitation and Time-Varying Temperature Field

In this paper, the internal resonance characteristics of hyperelastic cylindrical shells under the time-varying temperature field are investigated for the first time, and the evolution of the isolated bubble is carried out. Through the analysis of the influences of temperature on material parameters, the hyperelastic strain energy density function in the unsteady temperature field is presented. The governing equations describing the axisymmetric nonlinear vibration are derived from the nonlinear thin shell theory and the variational principle. With the harmonic balance method and the arc length method, the steady state solutions of shells are obtained, and their stabilities are determined. The influences of the discrete mode number, structural and temperature parameters on the nonlinear behaviors are examined. The role of the parameter variation in evolution behaviors of isolated bubble responses is revealed under the condition of 3:1 internal resonance. The results manifest that both structural and temperature parameters can affect the resonance range of the response curve, and the perturbed temperature has a more significant effect on the stable region of the solution.

TEMPERATUREREGIME OF COAL BED BY UNDERGROUND COAL GASIFICATION IN THE FILTRATION CHANNEL

A mathematical model of the temperature regime of a coal bed during underground coal gasification in a filtration channel for new geotechnologies of Tula State University is developed. It is proposed to describe the unsteady temperature field of the coal seam with the one-dimensional heat conduction equation with the heat sink that depends on the temperature of the coal bed. The equation is solved for semi-infinite space. The results of computational experiments have shown that the temperature front from the fire face moves deep into the coal bed. Consequently, in the process of underground gasification, pre-heating of coal in the gasified block and thermal preparation take place. Quite quickly, after the formation of stable combustion of coal in the fire face, a stationary temperature profile is established.

Full-Annulus URANS Study on the Transportation of Combustion Inhomogeneity in a Four-Stage Cooled Turbine

The inhomogeneity of temperature in a turbine is related to the nonuniform heat release and air injections in combustors, which is commonly measured by thermal couples at the turbine exit. Investigation of temperature inhomogeneity transportation in a multistage gas turbine should help in detecting and quantifying the over-temperature or flameout of combustors using turbine exhaust temperature. Here, the transportation of combustion inhomogeneity inside the four-stage turbine of a 300-MW gas turbine engine was numerically investigated. The computational domain included four turbine stages, consisting of more than 500 blades and vanes. Realistic components (N2, O2, CO2, and H2O) with variable heat capacities were considered for hot gas and cooling air. Coolants were added to the computational domain through more than 19,000 mass and momentum source terms. An unsteady Reynolds averaged Navier–Stokes computational fluid dynamics (URANS CFD) run with over-temperature/flameout at 6 selected combustors out of 24 was carried out. The temperature distributions at rotor–stator interfaces and the turbine outlet were quantified and characterized using Fourier transformations in the space domain. It is found that the transport process from the hot streaks/cold streaks at the inlet to the outlet is relatively stable. The cold and hot fluid is redistributed in time and space due to the stator and rotor blades, and in the region with a large parameter gradient at the inlet, a strong unsteady temperature field and a composition field appear. The distribution of the exhaust-gas composition has a stronger correlation with the inlet temperature distribution and is less susceptible to interactions.