scholarly journals DEM-CFD Simulation and Experiments on the Flow Characteristics of Particles in Vortex Pumps

Water ◽  
2020 ◽  
Vol 12 (9) ◽  
pp. 2444
Author(s):  
Xiongfa Gao ◽  
Weidong Shi ◽  
Ya Shi ◽  
Hao Chang ◽  
Ting Zhao
Keyword(s):  
Numerical Simulation ◽  
High Speed ◽  
Cfd Simulation ◽  
Flow Characteristics ◽  
Solid Particles ◽  
Experimental Results ◽  
High Speed Photography ◽  
Inlet Section ◽  
Impeller Blade ◽  
Vortex Pump

Due to their outstanding anti-clogging ability, vortex pumps have been gradually promoted and applied in recent years. However, when transporting sewage containing solids, they will still encounter problems such as partial clogging, overwork wear, etc., therefore, it is particularly important to master the flow characteristics of solid particles in the vortex pump. In this paper, the Discrete Element Model-Computational Fluid Dynamics (DEM-CFD) coupled calculation method is introduced into the numerical simulation of vortex pumps and particles with diameters of 1, 2 and 3 mm and concentrations of 1% and 5%, were subjected to numerical simulation and study of the flow characteristics of the particles, then rapeseed was used to represent solid particles in tests. It was obvious that the CFD results were in good agreement with the experimental results, whereby the high speed photography experimental results of the pump inlet section show that the experimental results are consistent with the numerical simulation results. The results show that there are three typical movement tracks of solid particles in the vortex pump: in Track A particles flow through the impeller and enter the volute by the through flow, in Track B particles go directly into the volute through the lateral cavity under the influence of circulation flow and in Track C the particles enter the impeller from the front cover end area of the impeller blade inlet and then into the volute through the back half area of blade. It can be found that the particles are mainly distributed at the back of the volute.

A Study of White Smoke Generation and Its Numerical Simulation

1993 ◽  
Vol 207 (2) ◽  
pp. 101-106 ◽  
Author(s):  
T Shiozaki ◽  
T Otani ◽  
I Joko
Keyword(s):  
Numerical Simulation ◽  
High Speed ◽  
Experimental Results ◽  
Fuel Spray ◽  
High Speed Photography ◽  
Visualization Technique ◽  
Lean Mixture ◽  
Smoke Generation

A mechanism of white smoke generation is clarified by a visualization technique using high-speed photography. The adhered fuel spray on the wall of the cavity, the fuel in the lean mixture region, the spilled fuel from the combustion cavity and the fuel from the sac volume of the nozzle tip are converted to the white smoke late in the expansion stroke. Numerical simulation is also conducted and its results coincide well with experimental results.

Velocity characteristics in a multiphase pump under different tip clearances

2020 ◽  
pp. 095765092094653
Author(s):  
Guangtai Shi ◽  
Zongku Liu ◽  
Yexiang Xiao ◽  
Helin Li ◽  
Xiaobing Liu
Keyword(s):  
Velocity Distribution ◽  
Flow Rate ◽  
High Speed ◽  
Stokes Equations ◽  
Design Flow ◽  
Tip Clearance ◽  
High Speed Photography ◽  
Hydraulic Loss ◽  
Impeller Blade ◽  
Multiphase Pump

To investigate the effect of tip clearance on the velocity distribution in a multiphase pump, the internal flow and velocity distribution characteristics in pump under different tip clearances are studied using experimental and numerical methods. Simulations based on the Reynolds-Averaged Navier-Stokes equations (RANS) and the standard k-ε turbulence model are carried out using ANSYS CFX. Under conditions of inlet gas void fraction (IGVF) is 5% at the flow rate of 0.6Q, 0.7Q and 0.8Q (Q is the design flow rate), the accuracy of the numerical method is verified by comparing with the experimental data using high-speed photography. Results show that the leakage flow interacts with the main flow and evolves into the tip leakage vortex (TLV). Due to the TLV, the pressure, velocity, turbulent kinetic energy (TKE), vorticity and streamlines on the S2 stream surface in the impeller and diffuser are changed greatly under different tip clearances. The velocities at the impeller outlet and diffuser inlet along the radial direction are also changed. The axial velocity distribution is similar to the meridional velocity distribution at the impeller blade outlet. While the relative velocity and absolute velocity distribution show the opposite trends. In addition, the vorticity is larger near the tip separated vortex and the hydraulic loss in pump is also increased due to the TLV.

Flow Characteristics of Rectangular Liquid Jets Injected Into Low Subsonic Crossflow

2019 ◽  
Author(s):  
M. Tadjfar ◽  
A. Jaberi ◽  
R. Shokri
Keyword(s):  
High Speed ◽  
Flow Characteristics ◽  
Combustion Efficiency ◽  
Liquid Jets ◽  
High Speed Photography ◽  
Aspect Ratios ◽  
Jet Trajectory ◽  
Wide Range ◽  
Circular Holes ◽  
Subsonic Crossflow

Abstract Perpendicular injection of liquid jets into gaseous crossflow is well-known as an effective way to obtain good mixing between liquid fuel and air crossflow. Mostly, injectors with circular holes were used as the standard method of fuel spraying. However, recently a great attention to injectors with non-circular holes has emerged that aims to improve the quality of fuel mixing and consequently combustion efficiency. In the present work, rectangular injectors with different aspect ratios varying from 1 to 4 were experimentally studied. Using a wind tunnel with maximum air velocity of 42 m/s, tests were performed for a wide range of flow conditions including liquid-to-air momentum ratios of 10, 20, 30 and 40. Backlight shadowgraphy and high speed photography were employed to capture the instantaneous physics of the liquid jets discharged into gaseous crossflow. The flow physics of the rectangular liquid jets were investigated by means of flow visualizations. Different regimes of flow breakup including capillary, arcade, bag and multimode were observed for rectangular jets. Moreover, a new technique was used to calculate the trajectory of the liquid jets. It was shown the nozzle’s shape has no significant effect on jet trajectory. Also, the momentum ratio was found to has a profound effect on jet trajectory.

Research of bubble flow characteristics in microfluidic chip

2017 ◽  
Vol 31 (10) ◽  
pp. 1750109
Author(s):  
Chao Qiu ◽  
Han Cheng ◽  
Shuxian Chen
Keyword(s):  
Heat Flux ◽  
Microfluidic Chip ◽  
High Speed ◽  
Flow Characteristics ◽  
Hydrophobic Surface ◽  
High Speed Photography ◽  
Bubble Flow ◽  
Hydrophilic Surface ◽  
Biological Detection ◽  
Speed Up

Bubble is the heart of the microfluidic chip, which takes a significant role in drug release, biological detection and so on. In this case, bubble flow characteristics in microfluidic chip are the key to realize its function. In this paper, bubble flow characteristics in the microfluidic chip have been studied with high speed photography system by controlling the wettability and the heat flux of the microelectrode surface. The result shows that bubble flows faster on the electrode with hydrophobic surface. In addition, loading current to the electrode with hydrophilic surface could also speed up the movement of bubble, and the flow rate of bubble increases with the increasing heat flux of the electrode.

Numerical simulation of the stalled flow within a vaned centrifugal pump

2004 ◽  
Vol 218 (4) ◽  
pp. 425-435 ◽  
Author(s):  
K M Guleren ◽  
A Pinarbasi
Keyword(s):  
Numerical Simulation ◽  
Centrifugal Pump ◽  
High Speed ◽  
Stokes Equations ◽  
Reverse Flow ◽  
Flow Characteristics ◽  
Navier Stokes ◽  
Leakage Flow ◽  
Navier Stokes Equations ◽  
Low Pass

The main goal of the present work is to analyse the numerical simulation of a centrifugal pump by solving Navier-Stokes equations, coupled with the ‘standard k-∊’ turbulence model. The pump consists of an impeller having five curved blades with nine diffuser vanes. The shaft rotates at 890r/min. Flow characteristics are assumed to be stalled in the appropriate region of flowrate levels of 1.31-2.861/s. Numerical analysis techniques are performed on a commercial FLUENT package program assuming steady, incompressible flow conditions with decreasing flowrate. Under stall conditions the flow in the diffuser passage alternates between outward jetting when the low-pass-filtered pressure is high to a reverse flow when the filtered pressure is low. Being below design conditions, there is a consistent high-speed leakage flow in the gap between the impeller and the diffuser from the exit side of the diffuser to the beginning of the volute. Separation of this leakage flow from the diffuser vane causes the onset of stall. As the flowrate decreases both the magnitude of the leakage within the vaneless part of the pump and reverse flow within a stalled diffuser passage increase. As this occurs, the stall-cell size extends from one to two diffuser passages. Comparisons are made with experimental data and show good agreement.

Experimental and Numerical Study of Hydrodynamic Cavitation of Orifice Plates with Multiple Triangular Holes

2012 ◽  
Vol 256-259 ◽  
pp. 2519-2522 ◽  
Author(s):  
Zhi Yong Dong ◽  
Qi Qi Chen ◽  
Yong Gang Yang ◽  
Bin Shi
Keyword(s):  
Velocity Profile ◽  
High Speed ◽  
Numerical Study ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Orifice Plate ◽  
Hydrodynamic Cavitation ◽  
High Speed Photography ◽  
Hydraulic Characteristics ◽  
Image Velocimetry

Hydraulic characteristics of orifice plates with multiple triangular holes in hydrodynamic cavitation reactor were experimentally investigated by use of three dimensional particle image velocimetry (PIV), high speed photography, electronic multi-pressure scanivalve and pressure data acquisition system, and numerically simulated by CFD software Flow 3D in this paper. Effects of number, arrangement and ratio of holes on hydraulic characteristics of the orifice plates were considered. Effects of arrangement and ratio of holes and flow velocity ahead of plate on cavitation number and velocity profile were compared. Distribution of turbulent kinetic energy and similarity of velocity profile were analyzed. And characteristics of cavitating flow downstream of the orifice plate were photographically observed by high speed camera. Also, a comparison with flow characteristics of orifice plate with hybrid holes (circle, square and triangle) was made.

Experimental Investigation of the Characteristics of Dynamic Cutting Process

1977 ◽  
Vol 99 (2) ◽  
pp. 410-418 ◽  
Author(s):  
M. M. Nigm ◽  
M. M. Sadek
Keyword(s):  
Experimental Investigation ◽  
Theoretical Model ◽  
High Speed ◽  
Cutting Speed ◽  
Chip Thickness ◽  
Shear Plane ◽  
Rake Angle ◽  
Experimental Results ◽  
High Speed Photography ◽  
Cutting Coefficients

The dynamic response of the shear plane and the variations of the dynamic cutting coefficients are experimentally investigated at various values of feed, cutting speed, rake angle, clearance angle, frequency, and amplitude of chip thickness modulation. Wave generating and wave removing cutting tests, in which high-speed photography is used to investigate the geometry of chip formation, are carried out. The theoretical model of dynamic cutting developed in [1] is assessed with reference to these experimental results. A comparison between this model and previous models in relation to the experimental results is also presented.

Experiment and Numerical Simulation of Extrudate Swell in the Polymer Extrusion Process

2011 ◽  
Vol 314-316 ◽  
pp. 401-404 ◽  
Author(s):  
Min Zhang ◽  
Chuan Zhen Huang ◽  
Guo Wen Chen ◽  
Yu Xi Jia
Keyword(s):  
Numerical Simulation ◽  
High Speed ◽  
Three Dimensional ◽  
Simulation Method ◽  
Extrusion Process ◽  
High Speed Photography ◽  
The Finite Element Method ◽  
Polymer Extrusion ◽  
Extrudate Swell ◽  
Rate Profile

The extrudate swell of the polymer extrusion process was studied with the experiment and simulation method. The extrudate swell process was recorded by the high-speed photography apparatus. The swell rate at the different time was calculated. It is found that the extrudate swell rate increase at the first five seconds. The maximum swell rate is about 4.37%. The three-dimensional numerical simulation model of the experiment die path was founded. The extrusion process including the extrudate swell was simulated used the Finite Element Method. Such simulated results as the velocity vector, the shear rate profile and the end of the swell zone were analyzed. The extrudate swell end got by the simulation is similar with the experiment result.

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