Vol 6, No 2 (2020)
- Year: 2020
- Articles: 5
- URL: https://journals.ssau.ru/dynvibro/issue/view/435
Full Issue
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Abstract
For units providing flow control for cryogenic fluids and operating under conditions of a significant change in the temperature range from positive to cryogenic and in a two-phase state of the working fluid, the problem of sealing the closure members of the units (valve pairs) becomes urgent.
Joint sealing is ensured by creating contact pressure in the joint through deforming the roughness peaks obtained by surface treatment of the valve pair.
The mechanical properties of the materials of the contacting valve pairs change significantly under the influence of cryogenic temperatures. First of all, the plastic properties are reduced, therefore, the creation of increased contact pressure is required.
The article presents a methodology for evaluation of changes in the microgeometry of contacting surfaces depending on the specific contact pressure. It also allows one to evaluate the conductivity of microgaps in the viscous and molecular regimes of fluid flow through contacting surfaces. | |
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When creating specialized pumping test stands for hydraulic devices to check their vibration and noise characteristics, the main problem is the choice of pump type. This, in the first place, is connected with the different principle of operation of pumping units and the influence that the working organ exerts on the flow of liquid.
Currently, there is a wide range of pumps, differing in design, with different functional capabilities, supplying the working medium both at the nominal mode, and allowing to regulate supply and pressure parameters in a wide range. They are divided into two main groups: dynamic and voluminous. The choice of the pump for the needs of creating a stand determines its own vibra-tion characteristics of the entire system being created.
Proceeding from the made choice, it is necessary to determine the own charac-teristics of the created stand and, if necessary, to develop and apply a number of additional tools that allow improving the vibrational and noise characteristics of the stand being created.
The article presents the procedure for creating such a stand and describes the solutions that allow to combat the influence of the pump unit during the testing of hydraulics. The work was carried out using two types of pumps: axial-piston and centrifugal pumps. The following solutions were applied in the work: resonators, vibra-holding arrays, expansion tanks and flexible interchanges. The selection of the optimal combination and the correct calculation of the parameters of these means can significantly improve the intrinsic characteristics of the test stand being created and reduce own noise in the part of vibration and hydrodynamic noise. | |