Flow Development and Analysis of MHD Generators and Seawater Thrusters

The flow characteristics inside magnetohydrodynamic (MHD) plasma generators and seawater thrusters are analyzed and are compared using a three-dimensional computer model that solves the governing partial differential equations for fluid flow and electrical fields. Calculations have been performed for a Faraday plasma generator and for a continuous electrode seawater thruster. The results of the calculations show that the effects caused by the interaction of the MHD forces with the fluid flow are strongly manifested in the case of the MHD generator as compared to the flow development in the MHD thruster. The existence of velocity overshoots over the sidewalls confirm previously published results for MHD generators with strong MHD interaction. For MHD thrusters, the velocity profile is found to be slightly flatter over the sidewall as compared to that over the electrode wall. As a result, distinct enhancement of the skin friction exists over the sidewalls of MHD generators in comparison to that of MHD thrusters. Plots of velocity profiles and skin friction distributions are presented to illustrate and compare the flow development in MHD generators and thrusters.

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Interactions between Tandem Cylinders in an Open Channel: Impact on Mean and Turbulent Flow Characteristics

Water ◽

10.3390/w13131718 ◽

2021 ◽

Vol 13 (13) ◽

pp. 1718

Author(s):

Hasan Zobeyer ◽

Abul B. M. Baki ◽

Saika Nowshin Nowrin

Keyword(s):

Turbulent Flow ◽

Open Channel ◽

Recirculation Zone ◽

Three Dimensional ◽

Flow Characteristics ◽

Flow Recirculation ◽

Tandem Cylinders ◽

Flow Development ◽

The Mean ◽

Recirculation Length

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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Three-dimensional Structures of Plasma and Fluid Flow in a Nonequilibrium Disk MHD Generator with Inlet Swirl

IEEJ Transactions on Power and Energy ◽

10.1541/ieejpes1990.119.7_828 ◽

1999 ◽

Vol 119 (7) ◽

pp. 828-833

Author(s):

Kazuya Shimizu ◽

Hiromichi Kobayashi ◽

Yoshihiro Okuno ◽

Shigeharu Kabashima

Keyword(s):

Fluid Flow ◽

Three Dimensional ◽

Mhd Generator ◽

Inlet Swirl

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Numerical Simulation of Full-Scale Three-Dimensional Fluid Flow in an Oscillating Reactor

Frontiers in Energy Research ◽

10.3389/fenrg.2021.674615 ◽

2021 ◽

Vol 9 ◽

Author(s):

Houjun Gong ◽

Mengqi Wu

Keyword(s):

Numerical Simulation ◽

Fluid Flow ◽

Flow Field ◽

Flow Rate ◽

Three Dimensional ◽

Flow Characteristics ◽

Full Scale ◽

Variation Patterns ◽

Oscillating Motion ◽

Resistance Coefficients

Marine reactors are subjected to additional motions due to ocean conditions. These additional motions will cause large fluctuation of flow rate and change the coolant flow field, making the system unstable. Therefore, in order to understand the effect of oscillating motion on the flow characteristics, a numerical simulation of fluid flow is carried out based on a full-scale three-dimensional oscillating marine reactor. In this study, the resistance coefficients of the lattice, rod buddle and steam generator are fitted, and the distribution of flow rate, velocity as well as pressure in different regions is investigated through the standard model. After additional oscillation is introduced, the flow field in an oscillating reactor is presented and the effect of oscillating angle and elevation on the flow rate is investigated. Results show that the oscillating motion can greatly change the flow field in the reactor; most of the coolant circulates in the downcommer and lower head with only a small amount of coolant entering the core; the flow fluctuation period is consistent with the oscillating period, and the flow variation patterns under different oscillating conditions are basically the same; since the flow amplitude is related to oscillating speed, the amplitude of flow rate rises when decreasing the maximum oscillating angle; the oscillating elevation has little effect on the flow rate.

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Liquid Flow Characteristics in Microchannels

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.130-134.1484 ◽

2011 ◽

Vol 130-134 ◽

pp. 1484-1490

Author(s):

Yan Feng Liu ◽

Hong Wei Li ◽

Jing Wei Zhang ◽

Jin Xue

Keyword(s):

Heat Transfer ◽

Experimental Data ◽

Fluid Flow ◽

Three Dimensional ◽

Flow Characteristics ◽

Simulation Methods ◽

Dimensional Model ◽

Three Dimensional Model ◽

Simulation Results ◽

Poiseuille Number

A three-dimensional model was developed to simulate the laminar flow and convective heat transfer in rectangular silicon microchannels，which have hydraulic diameter of 95.3，92.3 ,85.8 , 80 and 75μm respectively．The rationality of the simulation methods and results were validated by comparing with experimental data. The simulation results indicate that the aspect ratio has a significant impact on the Poiseuille number. Conventional ﬂuid ﬂow theory is fit for researching the fluid flow in microchannels, Po is a constant that is not dependent on the Reynolds number.

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A numerical study of inkjet refilling

Proceedings of the Institution of Mechanical Engineers Part C Journal of Mechanical Engineering Science ◽

10.1243/0954406042690533 ◽

2004 ◽

Vol 218 (12) ◽

pp. 1481-1497

Author(s):

K-S Yang ◽

I-Y Chen ◽

C-C Wang

Keyword(s):

Fluid Flow ◽

Bubble Growth ◽

Stokes Equations ◽

Numerical Study ◽

Three Dimensional ◽

Flow Characteristics ◽

Navier Stokes ◽

Channel Design ◽

Navier Stokes Equations ◽

Inkjet Printer

A numerical study is conducted to examine the flow characteristics of the inkjet printer head with special attention made to the refilling process. By solving the full set of three-dimensional transient Navier-Stokes equations and considering the process of bubble growth and collapse as a movable membrane, the fluid flow inside the channel and the ejected droplet from the nozzle can be modelled. The calculated results indicate that the single refilling channel design provides the fastest refilling rate but also reveals pronounced flow surge/overshot phenomena. By using a double refilling channel design, the flow surge/overshot phenomenon can be reduced considerably owing to the imposed friction. Moreover, the flooding phenomenon is much less pronounced. However, placing an additional cylinder obstacle in the single filling channel will not reduce the flow surge/overshot phenomenon.

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Three-Dimensional Laminar Heat Transfer and Fluid Flow Characteristics in the Entrance Region of a Rhombic Duct

Journal of Heat Transfer ◽

10.1115/1.3250585 ◽

1988 ◽

Vol 110 (4a) ◽

pp. 855-861 ◽

Cited By ~ 21

Author(s):

Y. Asako ◽

M. Faghri

Keyword(s):

Heat Transfer ◽

Fluid Flow ◽

Three Dimensional ◽

Flow Characteristics ◽

Entrance Region ◽

Perfect Agreement ◽

Entry Length ◽

Uniform Wall Temperature ◽

Uniform Wall ◽

Fluid Flow Characteristics

A solution methodology is developed to obtain three-dimensional fluid flow and heat transfer characteristics in the entrance region of a rhombic duct. Owing to the complexity of the geometry, the literature results are limited to the fully developed values. The numerical methodology is based on an algebraic coordinate transformation technique, which maps the complex cross section onto a rectangle, coupled with a calculation procedure for three-dimensional parabolic flows, which reduces the problem to a series of two-dimensional problems. The Nusselt number and friction factor results are obtained for boundary conditions of uniform wall heat flux and uniform wall temperature. The asymptotic values of the Nusselt numbers and friction factors approach the available fully developed results. The entry length results for the limiting case of φ = 90 deg are in perfect agreement with the available experimental and numerical results for a rectangular duct.

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Modeling of GMA Weld Pools With Consideration of Droplet Impact

Journal of Engineering Materials and Technology ◽

10.1115/1.2807020 ◽

1998 ◽

Vol 120 (4) ◽

pp. 313-320 ◽

Cited By ~ 20

Author(s):

Zhen Ning Cao ◽

Pingsha Dong

Keyword(s):

Fluid Flow ◽

Weld Pool ◽

Surface Deformation ◽

Impact Force ◽

Gma Welding ◽

Three Dimensional ◽

Flow Characteristics ◽

Heat Content ◽

Heat Transfer Process ◽

Droplet Impact

A three-dimensional weld pool model has been developed to study the fluid flow and heat transfer process during gas metal arc (GMA) welding. Both droplet heat content and impact force were considered in analyzing the effect of droplets on the formation of weld pool. The fluid flow in the weld pool was induced by the presence of surface tension, electromagnetic and buoyancy force. The surface deformation of weld pool was calculated by considering arc pressure and droplet impact force. Computational results under partial and full penetration welding conditions were obtained. The effect of heat flow and fluid flow characteristics on weld pool geometry was discussed, particularly with respect to the presence of droplet heat input and impact force.

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