The Thermophysical Experiment Carried out for the Education of the Students Studying for the Master’s Degree to Get Heat Engineering Specialties

Анотація

Thermophysical experiments became a very rare phenomenon due to their expensiveness and rather complicated and time-consuming preparation and carrying out. Very often the teachers tend to prefer the computer simulation of these and those technological processes for the in-depth formation of detailed knowledge in students. The reason for such a preference is evident; this approach provides visual aspects and relatively fast attainment of the goal. A negative side of such a choice is that the future specialists are not able to judge the reliability of these and those experimental relationships between the physical parameters of the processes that are used for the machinery design. To remove this drawback of the teaching and learning process, a small-size aerodynamic tunnel was created and the detailed technique for the running of experiment and experimental data processing was elaborated. The length of the working section of this tunnel was equal to 0.5 m. The rectangular cross-section of the tunnel bore was equal to 0.35´0.15 m². The heat loss was studied at the lower wall of aerodynamic tunnel that was equipped with three heating elements arranged longitudinally to the air stream. The heating elements were the strips made of constantan with the cross-section of 10´0.11 mm² and the thermocouples were fixed to the lower surface. A maximum value of the local Reynolds number was Re_x < 10⁵, i.e. the laminar boundary layer was actually in progress on the entire surface. When processing the obtained experimental data we took into account radiation heat losses and the heat losses caused by thermal conductivity along heating elements. Nevertheless, heat transfer intensity values turned out to be 3 to 4 times higher in comparison to those of the laminar flow mode. The numerical analysis of the thermal state of the experimental plate enabled the determination of the heat losses that were not taken into account earlier. Hence, we managed to achieve actually full coincidence of the experimental values of the intensity of heat transfer that were derived from a reliable similarity equation. The research done is required for the formation of the competence in students that study for the Master’s degree to get their specialty.

Keywords: the heat transfer, the experiment, the aerodynamic tunnel, the rate, heat losses, heating elements, the thermocouple, and the master’s degree.