Aerospace Technic and Technology

Thermoacoustic thermal machines (TATM) is a relatively new and non-common type of thermal machines that differs significantly from conventional mechanical systems due to the lack of moving elements, environmental safety, and the ability to operate from external sources of energy. Thermoacoustic engines (TAE) - direct-acting thermal machines that are capable of converting thermal energy into mechanical in the form of powerful acoustic waves. The growing interest to TATM is related to the possibility of using them in energy saving systems since the introduction of energy saving technologies is an effective method for increasing the efficiency of power plants and reducing their harmful effects on the environment. The wide introduction of TATM is hampered by their low specific power, the complexity of the transformation of acoustic oscillations into mechanical work and lack of experience.

The article presents the results of experimental research on the operational characteristics of the thermoacoustic turbogenerator (TATG). The TATG consists of a thermoacoustic engine, which operates in the Brighton thermodynamic cycle and an electric generator. As an actuator of an electric generator, a pulsed bi-directional turbine was used. It is capable of converting the oscillatory motion of the working medium into mechanical energy. In the course of experiments, data were obtained on external characteristics of both TAE and TATG at different load conditions. The interaction of a pulsed bi-directional turbine with a pulsating working medium leads to the appearance of complex radial currents in the resonator that affects the efficiency of the energy conversion processes.

In the work, using CFD simulation, the peculiarities of formation and development of radial currents were studied. Boundary and initial conditions were imposed based on experimental data. The results of CFD experiments allowed us to study the influence of various factors on the intensity of radial currents. It is shown that radial currents exist in the form of quasistationary pulsating structures whose length depends on the amplitude of the oscillatory motion of the pulsating medium and the frequency of acoustic oscillations. The presence of these currents leads to the "desired" flow of input into the rectifying apparatus of the impulse turbine. According to the results of the research, technical solutions are proposed that prevent the formation of such currents.

bidirectional impulse turbine; thermoacoustic; CFD modeling; heat machines

Swift, G. W. Thermoacoustic: A unifying perspective for some engines and refrigerators. American Inst. of Physics, 2002. 300 p.

De Blok K., Low operating temperature integral thermoacoustic devices for solar cooling and waste heat recovery. Paris, Acoustic-2008, Inter. Conf. 2008. pp. 18–24.

Keolian, Robert M. Truck Thermoacoustic Generator and Chiller. Final Report. DOE Project DE-FC26-04NT42113 CPR/IW Project 17057. Applied Research Laboratory. The Pennsylvania State University. 2011. 190 р. DOI: 10.2172/1026487.

De Blok, K., Owczarek, P., Francois, M., Acoustic to electric power conversion. Available at: http://www.aster-thermoacoustics.com/ (accessed 08.02.2019).

Thakker, A., Hourigan, F Modeling and scaling of the impulse turbine for wave power applications. Renewable Energy, 2004, vol. 29, no. 3, pp. 305–317. DOI: 10.1016/S0960-1481(03)00253-2.

De Blok, K. Bi-directional turbines for converting acoustic wave power into electricity. Available at: http://www.aster-thermoacoustics.com/ (accessed 08.02.2019).

Korobko, V. V., Moskovko, O. O., Voronov. I. V. Doslidzhennya osoblyvostej vykorystannya impulsnyx dvonapravlenyx turbin v termoakustychnyx mashynax [Investigation use of feautures of puls bidirectional turbyne in thermoacoustic heat machines]. Naukovyj visnyk KhDMA – Scientific Bulletin of KhDMA, 2016, no. 1 (14), pp. 201-208.

Korobko, V. V., Moskovko, O. O., Mostipanenko, H. B., Serbin, S. I., Doslidzhennya roboty` impul`snoyi dvonapravlenoyi turbiny` v rezonatori termoakustychnogo dvyguna [Investigation of the operation of the pulse bi-directional turbine in the resonator of the thermoacoustic engine]. Aviacijno-kosmicna tehnika i tehnologia - Aerospace technic and technology, 2017, no. 8(143), pp. 19–25.

Kloprogge, T. Turbine design for thermo-acoustic generator : Masters thesis. Aeronautical Engineering, Hogeschool Holland Delft, 2012. 72 p.