Experimental and numerical study of cavitating particulate flows in a Venturi tube

The Venturi tube measures the fluid’s flowrate by use of an obstruction in the flow path. As a tool to understand the fundamental principles of Chemical Engineering, an experimental device for flow measurement integrating a Venturi tube was developed in the course of the Chemical Engineering Projects I from the Federal University of Lavras. The system was constructed with materials of low-cost and easy access. The experimental results for the flow and pressure drop were compared with theorical values and with additional data obtained by the use of a numerical and computational method (CFD). The discharge coefficient was 0.680 ± 0.018 [-], an intermediate value of those found in the literature for orifice plate and flow nozzle meters. The numerical method was successfully able to predict the pressure drop in the system.

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Numerical study on pre-film atomization mechanism and characteristics by a coaxial swirl injector

Proceedings of the Institution of Mechanical Engineers Part A Journal of Power and Energy ◽

10.1177/0957650919844045 ◽

2019 ◽

Vol 233 (8) ◽

pp. 1022-1038

Author(s):

Qun Zhang ◽

Xin Wang ◽

Rui Kou ◽

Chaochao Li ◽

Peng Zhang ◽

...

Keyword(s):

Liquid Film ◽

Size Distribution ◽

Droplet Size ◽

Numerical Study ◽

Droplet Size Distribution ◽

Venturi Tube ◽

Experimental Results ◽

Two Stage ◽

Spray Cone ◽

Fuel Flow

The overall process and mechanism of the centrifugal pre-film atomization with double swirling flow were studied using the methods of large Eddy simulation and volume of fluid. The atomization process includes a centrifugal jet under the primary swirl and a pre-film atomization under the two-stage counter-rotating swirl at the venturi outlet. The fuel is ejected from the outlet of the centrifugal nozzle and undergoes the transient process of reaching the venturi throat. The breaking mechanism of liquid film in this process is the same as that of the formation mechanism of the mushroom-shaped tip of liquid jet. The numerical simulation results are highly consistent with the experimental results. For the formation and development of the liquid film on the venturi wall, collision and wave action promote the expansion of the liquid film. At the outlet position of the venturi tube, the short wave mode and the two-stage reverse swirling structure play major roles in the fragmentation process of the flake liquid film, which coincides with the flow characteristics given by the experiment. It is found that the spray cone angle increases as the fuel flow rate increases, and the numerical results are basically consistent with the predicted values of the empirical formula under different fuel flow rates. The droplet size distribution showed a Poisson distribution during the atomization of centrifugal jets and pre-film, and the peak position and variation trend of the droplet size distribution at the outlet of the venturi tube were basically consistent with experimental results.

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A Combined Soft-Sphere Collision/Immersed Boundary Method for Resolved Simulations of Particulate Flows

ASME 2010 3rd Joint US-European Fluids Engineering Summer Meeting: Volume 1, Symposia – Parts A, B, and C ◽

10.1115/fedsm-icnmm2010-30634 ◽

2010 ◽

Cited By ~ 8

Author(s):

Wim-Paul Breugem

Keyword(s):

Immersed Boundary Method ◽

Numerical Study ◽

Stokes Number ◽

Immersed Boundary ◽

Particulate Flows ◽

Collision Model ◽

Soft Sphere ◽

Boundary Method ◽

Numerical Grid ◽

Gap Width

A second-order accurate and efficient Immersed Boundary Method (IBM) has been developed for simulating particle-laden flows. Recently, this method has been combined with a soft-sphere collision model to accommodate inter-particle and particle-wall collisions. Details of the collision model are given. Results are shown from a lubrication study of non-touching particles at close distance from each other. The numerical results for the drag force acting on the particles agree well with exact solutions, except when the gap width between the particles becomes significantly smaller than the numerical grid spacing. For very small gap width, lubrication force corrections are proposed for the normal approach between particles based on asymptotic analytical solutions. Results are presented from a numerical study of sphere-wall collisions in a viscous fluid. The simulated behavior of the coefficient of restitution as function of the Stokes number based on the particle impact velocity, is in good agreement with experimental data.

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Numerical Study on Flow Control Performance of a Cavitation Venturi Tube

Heat Transfer Research ◽

10.1615/heattransres.2018024688 ◽

2018 ◽

Author(s):

Xiaodong Hu ◽

Fuyu Liu ◽

Zhixi Liang ◽

Liang Gong

Keyword(s):

Flow Control ◽

Numerical Study ◽

Venturi Tube ◽

Control Performance

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Numerical Study on the Power Efficiency and Flow Characteristics of a New Type of Wind Energy Collection Device

Applied Sciences ◽

10.3390/app10217438 ◽

2020 ◽

Vol 10 (21) ◽

pp. 7438 ◽

Cited By ~ 1

Author(s):

Li Ding ◽

Tongqing Guo

Keyword(s):

Wind Energy ◽

Power Efficiency ◽

Numerical Study ◽

Flow Characteristics ◽

Aerodynamic Characteristics ◽

Venturi Tube ◽

Speed Ratio ◽

Wind Turbine System ◽

Collection Device ◽

Improved Design

The increased velocity (Invelox) wind turbine system is a novel wind energy collection device. This system can collect and accelerate the air flow through a funnel and a Venturi tube. However, the efficiency of this system is relatively low under some wind directions. To improve the aerodynamic performance of Invelox, a straight-through layout with a windshield was proposed. The flow field of the improved design was studied by applying Computational Fluid Dynamics (CFD) and was compared with that in the original configuration. Numerical results show that when the Invelox exit is facing the incoming wind, the ratio of the average velocity inside the Venturi tube to the incoming wind speed, i.e., the speed ratio, will drop sharply, and even the airflow will push back. The improved layout can eliminate the sensitivity of incoming wind direction to aerodynamic characteristics. The windshield can effectively reduce the interference of incoming air to the outlet air, making the speed ratio increase by about 42%. Different wind profiles in the atmospheric boundary layer are used in the boundary of the flow domain as the incoming flow wind. With the increase in the wind profile index, the speed ratio of the Invelox system will gradually decrease.

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