scholarly journals Three-dimensional modeling of flow characteristics and the influence of non-hydrostatic pressure in a 193° sharp open channel bend

Author(s):  
Y Xing ◽  
D L Zhao ◽  
D G Ma ◽  
W D Gan
Processes ◽  
2021 ◽  
Vol 9 (6) ◽  
pp. 1025
Author(s):  
Zhu Jiang ◽  
Haiying Li ◽  
Guangtai Shi ◽  
Xiaobing Liu

The internal flow is very complex in the multiphase pump, especially in the static impeller, where the flow is more disorganized than that in the impeller wheel, and it will cause greater hydraulic losses. In order to investigate deeply the flow rules within the static impeller, all kinds of the flow losses are analyzed quantificationally in the multiphase pump. Based on the standard SST k-ω turbulence model, selected the helical axial flow multiphase pump as the research object, used the three-dimensional modeling software for the three-dimensional modeling of the flow through parts of the multiphase pump, such as impeller wheel, the static impeller, the suction chamber, and the extrusion chamber. The ANSYS software is used to simulate the three-dimensional flow in static impeller, and the ICEM software was used to divide the mesh of suction chamber, press outlet chamber, moving impeller and static impeller respectively. The results show that the flow within the impeller wheel is more uniform than the static impeller, and larger axial vortexes appear in the static impeller. Compared with the impeller wheel, the effect of the flow rate on the flow within the first static impeller is greater. The friction loss is the largest among all kinds of losses in the static impeller, followed by the turbulence dissipation loss. What’s more, the shock loss and the contraction loss are the smallest, they are all less than 20%, and the main loss within the static impeller are the turbulent dissipation loss and friction loss. The proportion of energy losses in the first and second static impeller is almost the same, which is around 50%, respectively. The results can be used as a reference for the improvement of the hydraulic performance of the multiphase pump.


Author(s):  
A. Agarkov ◽  
R. Sharapov

Various designs of inertial concentrators for cleaning dusty air are considered. The analyzed designs of devices for separating dust particles by fractions also have a number of disadvantages: low fractional efficiency and complexity of structures when divided into several fractions. The design of an inertial dust concentrator with adjustable parameters is proposed. This design of the concentrator provides an increase in fractional efficiency and a decrease in hydraulic resistance with the simplicity of the apparatus design. Three-dimensional modeling of the spatial motion of air in an inertial dust concentrator with adjustable parameters is performed. A system of equations describing gas-dynamic flows is given. The results of calculations of velocity and pressure in an inertial dust concentrator with adjustable parameters are presented. Reflecting vanes and a false wall inside an inertial concentrator act as deflectors, that is, deflect the flow, which leads to an increase in the time spent by suspended particles in the inertial concentrator and a decrease in their kinetic energy. In this case, the role of inertia forces on the motion of particles will increase. Numerical modeling of the three-dimensional air flow in the concentrator made it possible to obtain a flow pattern and the main flow characteristics (velocity and pressure) from the moment of air supply to the concentrator to the moment of establishing the flow.


Water ◽  
2021 ◽  
Vol 13 (13) ◽  
pp. 1718
Author(s):  
Hasan Zobeyer ◽  
Abul B. M. Baki ◽  
Saika Nowshin Nowrin

The flow hydrodynamics around a single cylinder differ significantly from the flow fields around two cylinders in a tandem or side-by-side arrangement. In this study, the experimental results on the mean and turbulence characteristics of flow generated by a pair of cylinders placed in tandem in an open-channel flume are presented. An acoustic Doppler velocimeter (ADV) was used to measure the instantaneous three-dimensional velocity components. This study investigated the effect of cylinder spacing at 3D, 6D, and 9D (center to center) distances on the mean and turbulent flow profiles and the distribution of near-bed shear stress behind the tandem cylinders in the plane of symmetry, where D is the cylinder diameter. The results revealed that the downstream cylinder influenced the flow development between cylinders (i.e., midstream) with 3D, 6D, and 9D spacing. However, the downstream cylinder controlled the flow recirculation length midstream for the 3D distance and showed zero interruption in the 6D and 9D distances. The peak of the turbulent metrics generally occurred near the end of the recirculation zone in all scenarios.


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