EXCITATION OF HARMONIC TEMPERATURE WAVES IN A SOLID SAMPLE OF MATERIAL WITH CONVECTIVE HEATING

Abstract

The article discusses the method and means of exciting harmonic temperature waves in a solid sample material during convective heating, it is typical for the working conditions of heat-stressed assemblies and parts in power plants systems. A supersonic jet of combustion products is used as a heat transfer agent. The scheme of power supply feed and control of the mode of operation of the gas generator is considered, which makes it possible to reliably regulate the modes of its operation and to obtain stable values of the heat transfer agent temperature. For determining the temperature of the heat transfer agent, the method of accounting for losses in the combustion chamber with using pulse coefficients is considered. To create a variable thermal effect, the property of the supersonic (barrel) section was used, consisting of the substantial non-uniformity of the distribution of gas-dynamic parameters along its length. The movement of the sample relative to the jet must be carried out at a variable speed. For determining this pattern, we analyzed the coordinates of the shock-wave structure in order to transform its linear coordinates into phase ones. The property of the logarithmic spiral is used. It is established that the growth coefficient of the logarithmic spiral for the first barrels from the nozzle exit varies slightly. The scheme of the device for the excitation of the temperature wave in the sample. The sample is placed on the worktable, which reciprocates relative to the jet (the section of the first half of the second barrel is used). The worktable drive carried out by a cam rotating at a constant speed. The cam profile is carried out along sections of the spiral branches (right and left), in this case, the pressure of the gas jet on the working surface changes according to a harmonic law. The heat transfer coefficient is proportional to the pressure. To determine the thermophysical characteristics of the material in the experiment, it is sufficient to measure the phase shift between the temperature oscillations of the second surface in the sample and the heat flow oscillations (gas pressure on the obstacle). The accuracy of such measurements is higher than when measuring parameters with continuous heating of the sample

Keywords

• сверхзвуковая струя
• генератор струи
• ударно-волновая структура, конвективный нагрев
• возбуждение температурных волн в образце материала