The aim of the article is improvement of numerical cavitation models for simulation of an effect of cavitation stabilization of fluid mass flow. The methods of development of a new dynamic component for a numerical model of cavitation mass transfer is presented in the paper. Application of the new method resulted in a new dynamic component for numerical model of cavitation mass transfer, which takes into account fluid viscosity in Reley-Plesset equation. Relying on the methods being considered fundamentally new hydroautomatic devices such as cavitation mass flow stabilizers and flow dividers could be designed. The new dynamic component has become the basis for the new numerical model of cavitation mass transfer. The effect of cavitation stabilization of fluid mass flow was simulated by this dynamic component. The numerical model was verified by experimental researches of the effect of cavitation stabilization of fluid mass flow in a jet element "pipe-pipe". The results of simulation showed that the new numerical model of cavitation mass transfer can simulate the jet pipes with the difference between results of simulation and experiment not exceeding 2,5% and visualizing a cavitation zone more adequate.
The problems of braking and positioning of hydraulic actuators are an integral part of output speed control in hydro-pneumatic actuators. This article is focused on a hydraulic braking of driven elements of machines and mechanisms which is carried out by devices known as brake valves (counterbalance, load control, over-centre valves). Brake valves are used to exclude overrunning speed under passing loads when the external load direction coincides with the direction of movement (rotation) of the hydraulic actuator. They provide a constant pressure in pressure line and prevent cavitation. In this article the design and operation of brake valves are analyzed. The need for brake valves in hydraulic machines with hydraulic actuators under a passing load is proved. As a result of theoretical research a mathematical model of dynamics of hydraulic actuator with a brake valve has been developed. This model unlike others takes into account the design of main and control spools of the brake valve. The problem of logging-running unit braking is solved by the use of the hydraulic brake valve as a part of hydraulic logging system.
There is a need to ensure a high level of safety of the aircraft's flight, in particular with regard to the redundancy of the hydraulic system. However, the introduction of additional hydraulic circuits entails, in addition to the advantages and many disadvantages, such as increasing the complexity and weight of the hydraulic system. One of the compromises in this situation was the installation of a power transfer unit. In this article, schematic solutions and peculiarities of operation of power transfer units, cases of their use are considered. An analysis of the current problems and possibilities of improving such aggregates is presented. Possible directions of further development of power transmission units have been identified. In particular, the directions for increasing pressure, reducing the gas content of the liquid, using pump power regulators, reducing gaps, reducing noise and temperatures, and introducing an intelligent component are highlighted. Possibilities for installation of power regulators, their various circuit solutions and operating principles are described. The characteristics of regulators , the operation of which is based on the principle of load sensitivity, the possibility of using these regulators to optimize the operation of the power transfer unit, and, therefore, increase the accuracy, stability, controllability of the entire hydraulic system of the aircraft are presented.
Determination of critical temperatures A c1 and A c3 in steels alloying system H2G2S2MF using the dilatometric method and the method of testing quenching.
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