hydraulic processes
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Author(s):  
Robert Santa

Abstract The presence of the lubricant POE 68 in the refrigeration system changes the thermophysical properties of the refrigerant, which significantly affects the heat transfer and the hydraulic processes. The purpose of this research is to investigate the thermodynamic properties of the R152a, R125, R134a and R123 refrigerant and POE 68 lubricant mixtures at different temperatures from 233,15 to 313,15 K. There have been investigated the values of the densities and kinematic viscosities of the mixtures at different concentrations (100%, 90%, 80%). Finally, it was found that, the density and kinematic viscosity of the R123/POE 68 mixture were most affected by the change of the concentration.


2021 ◽  
Vol 2088 (1) ◽  
pp. 012031
Author(s):  
Hossein Abdi ◽  
O I Melikhov ◽  
V I Melikhov

Abstract Experiments on two-phase flow across an in-line tube bundle are analyzed with the STEG code, which has been developed for modeling thermal-hydraulic processes in a horizontal steam generator (SG). An adiabatic, vertical two-phase flows of air-water across horizontal in-line, 5 x 20 rod bundles, with a pitch-to-diameter ratio P/D=1.3 are considered, the mass velocity is varied in the range 27 - 818 kg/m2s. The calculated values of void fraction in the tube bundle are compared with the experimental ones measured by a gamma densitometer. A reasonable agreement between the calculations and the experimental data is obtained.


2021 ◽  
Author(s):  
Da-Peng Zhu ◽  
Jia-Mei-Hui Zhang ◽  
Lei He

Abstract The problem of seepage erosion is widespread in occurrence, but is rarely recognized as one of landslide causes. This paper describes and explains one event of slope erosion in Jianghan plain and is focused on the role of seepage erosion. The laboratory test is performed to reconstruct the hydraulic processes leading to slope failure with the application of different hydraulic loads. The observation and measurement reveal that slope alteration experienced three stages under seepage, and hydraulic gradient played a key role during seepage erosion phase. Using these results, a CFD-DEM model is developed to investigate how the seepage-induced soil particle migration would affect the slope evolution. The geotechnical properties control the failure processes and cause a significant change to the toe erosion and loosened zone. Although the instability of slope is mainly attributed to seepage gradient force, the occurrence of seepage erosion affects the failure mode. This work provides new guidance for hydrodynamic landslide prevention.


Water ◽  
2021 ◽  
Vol 13 (17) ◽  
pp. 2317
Author(s):  
Enrique Peña ◽  
Jose Anta

Laboratory experiments and field works play a crucial role in hydraulic research, development, and design as many hydraulic processes elude analytical formulation or, at least for the time being, are not readily nor accurately reproducible with numerical simulations [...]


2021 ◽  
Vol 1035 (1) ◽  
pp. 012036
Author(s):  
A A Sataev ◽  
V V Andreev ◽  
A V Duntsev ◽  
D I Novikov ◽  
A A Berezin

2021 ◽  
Vol 7 (1) ◽  
pp. 48-55
Author(s):  
Vladyslav Lysiak ◽  
◽  
Mykhailo Oliinyk

The contemporary state of the modelling of the pump station’s electric drive in a complex with its centrifugal hydraulic load has been analysed. It was found that most studies focus either on the modelling and development of automatic control systems for the asynchronous electric drive of pumps or on the optimization of performance indicators of the station as a whole. Besides, usually only one of the subsystems of a pumping station (or an electrically-operated pump unit) is modelled with a good degree of detail: either electromagnetic or hydraulic. This approach does not allow a concurrent research of electromagnetic and hydraulic processes in them. The paper proposes a comprehensive mathematical model of the dynamic modes of the synchronous electrically-operated centrifugal pump unit with a pipeline, in which the electromagnetic and hydraulic subsystems are presented with a balanced degree of detail. The developed model was verified and its viable applications were suggested.


2021 ◽  
Vol 263 ◽  
pp. 02032
Author(s):  
Dilbar Abduraimova ◽  
Makhsud Otaxonov ◽  
Elza Tursunova ◽  
Davron Allayorov ◽  
Sarvar Melikuziyev

The article evaluates the hydraulic processes in the collectors which constructed in irrigated fields. Illuminated the washing processes under the influence of the flow velocity in the collector bed. In order to study the washing processes in the collector basin, are covered the results of research conducted in the self-washing collector in natural field conditions. Collector 2-K-4 in Khavas district of Syrdarya region was selected as the object of research. Given cases of changes in the project parameters as a result of washing processes in the core of the collector. Were selected 5 sections in the collector and hydraulic parameters were studied. was evaluated the effect of hydraulic processes on the collector core. The studied sections show cases of change of design parameters under the influence of hydraulic processes. Soil samples were taken from the reservoir and the mechanical composition was determined under laboratory conditions. Based on the laboratory and natural field conditions results, a special graph was developed for the design of collectors on the basis of non-washable speed.


Author(s):  
Dmitry A. Panasenkov ◽  
Alexandr P. Zaitsev ◽  
Nikita A. Pikalov ◽  
Alexandr B. Kartashov ◽  
Dmitry M. Dubinkin

2020 ◽  
Vol 1683 ◽  
pp. 022078
Author(s):  
O V Mitrofanova ◽  
A S Bayramukov ◽  
O A Ivlev ◽  
D S Urtenov ◽  
A V Fedorinov

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