Vol 4, No 2 (2018): 19.06.2018

In the presented article, the experience of the Samara State Technical University on the use of low-frequency cavitation in the technology of washing machine parts and devices is considered.
Based on the results of research conducted by STC "Reliability" of SamSTU, low-frequency cavitation washing plants and technologies have been developed and tested at enterprises with the use of industrial water without heating and detergents as a washing liquid: installation at JSC "Aviaagregat" for cleaning aluminum pipes of the chassis of aircraft when immersed in a cavitating liquid; installation for washing the packages of filter elements of oil systems of gas turbine aircraft engines; installations for jet-cavitation washing of products of complex shape and large dimensions - carrier rocket tanks at JSC "RCC" Progress ", large-sized axle box bearings of railway cars at JSC "Samara Bearing Plant" and in the wagon depots of Kinel and Samara stations of the Kuibyshev Railway, etc. without making constructive changes and reconfiguring their staffing scheme.
Developments have shown that washing parts with low-frequency cavitation is not only more productive than other known methods of washing, but also allows cleaning parts of a complex configuration with internal cavities and blind channels, successfully removing solid abrasive particles, carved in the surface of parts during grinding, etc.
The low-frequency cavitation units for cleaning parts by immersion in washing liquid and jet washing, presented in the article, provide a high level of quality and washing performance at a relatively low cost, which is confirmed by their industrial approbation.

Thermoacoustic engines are devices with external heat input, in which thermal energy is converted into energy of acoustic oscillations. Their main advantages include high energy conversion efficiency (up to 35%), minimal number of moving parts, high reliability, absence of contact seals and operation from a variety of heat sources (hydrocarbon fuels, thermal emissions, nuclear sources, solar radiation, etc.). The main goal of this work is to develop, manufacture and carry out the experimental investigations of the thermoacoustic traveling wave engine with a maximum heat input from the electric heating element up to 1000 W. The thermoacoustic engine includes an inertance tube, three heat exchangers, a regenerator, a thermal buffer tube and an acoustic resonator. Helium acts as the working fluid in the engine at an average pressure of 1.0 to 3.0 MPa. The frequency of acoustic oscillations on the steady-state operating mode of the engine is 96-98 Hz. The regenerator is made in the form of a package of metal screens and is the main element of the engine, in which thermoacoustic energy conversion is carried out. In experimental research the following tasks were solved: - determination of the optimal conditions for the excitation of acoustic oscillations in the internal contour of the thermoacoustic engine; - determination of the minimum onset temperature at which acoustic oscillation are excited; - determination of the dependences of the onset temperature, the frequency and the amplitude of acoustic oscillations from the input thermal power; - determination of the efficiency of the rmoacoustic energy conversion; In experimental studies, an optimal mean helium pressure is determined, which ensures the minimum heat exchanger temperature 436 К (163 °C) required to start the engine. The maximum value of the acoustic power generated by the regenerator was 90 W. At the same time, the efficiency of conversion of thermal energy into acoustic energy reached 22.5% at a heat exchanger-heater temperature of 317 °C. Also during the tests, it was possible to establish the dependences of the onset temperature, the frequency of acoustic oscillations and the amplitude of the acoustic pressure on the supplied thermal power. This type of engine described in this paper can be used in many practical applications.

For the modern steam generator feed water flow control systems and new generation products requirements for vibrating characteristics and hydrodynamic noise are significantly increased. Currently, control devices meet the requirements of regulatory documents on vibration noise characteristics developed in 1980-ies. To solve the problem of compliance with modern requirements previously flat (two dimensional – 2D) statement of problem was widely used. This approach does not give a complete and adequate picture of the physical fields of electro-hydraulic equipment. Therefore, it is necessary to gradually complicate the task and goes into a three-dimensional area. We have done joint work with a number of computational companies that distribute or produce the various types of code for computational fluid dynamics (CFD) in order to determine ways of improving the acoustic quality of our products by the means of three-dimensional mathematical modeling with obtaining physical field parameters. On the basis of received information we made out the subsequent verification of experimental studies of the valve model, which had been previously analyzed in CFD, at the test bench.