scholarly journals Curvature Effects on the Electromagnetic Force, Efficiency, and Heat Transfer of a Weak Low Profile Magneto-Hydrodynamic Blanket Propulsion System

2017 ◽  
Vol 10 (5) ◽  
pp. 1261-1270
Author(s):  
M. A. Feizi Chekab ◽  
P. Ghadimi ◽  
◽  
Keyword(s):  
Heat Transfer ◽  
Electromagnetic Force ◽  
Propulsion System ◽  
Curvature Effects ◽  
Low Profile

Taguchi parametric analysis of the effects of electrode and magnetic actuator characteristics on Lorentz forces and heat transfer of a weak low-profile magneto-hydrodynamic blanket propulsion system

2016 ◽  
Vol 231 (19) ◽  
pp. 3553-3568
Author(s):  
Mohammad A Feizi Chekab ◽  
Parviz Ghadimi
Keyword(s):  
Heat Transfer ◽  
Parametric Analysis ◽  
Design Method ◽  
Propulsion System ◽  
Effective Parameters ◽  
Water Conductivity ◽  
Low Profile ◽  
Electro Magnetic ◽  
Mhd Propulsion ◽  
Numerical Solver

Parametric studies are conducted on different aspects of a planar MHD propulsion system called propulsive MHD blanket. Effects of nine different parameters on the electro-magnetic thrust, efficiency, and heat transfer of the blanket are investigated. To efficiently conduct the parametric analysis, the Taguchi test design method is used and 16 cases are defined. The Ansys-CFX commercial code is utilized as numerical solver and the obtained results are validated using the Hartman problem which indicated a negligible error of 0.16%. Electromagnetism, energy, mass, and momentum equations are considered for the fluid domain and heat transfer and electromagnetism equations are solved for the solid domain. On one hand, magnet shapes and type are found to be the highest effective parameters, followed by the electrodes voltage, length, and width. On the other hand, a prediction of the best combination of parameters for obtaining the highest electro-magnetic thrust are statistically accomplished which has produced an electro-magnetic thrust of 18.02 N per square meter for the MHD blanket which is twice the maximum electro-magnetic thrust obtained in the 16 initial test cases. It is demonstrated in the present paper that the unique applications of propulsive MHD blanket can compensate the very low efficiencies of MHD systems. It has also been shown that efficiency can be improved by enhancing the water conductivity, which is intended as a future study.

scholarly journals Experimental study of curvature effects on jet impingement heat transfer on concave surfaces

2017 ◽  
Vol 30 (2) ◽  
pp. 586-594 ◽  
Author(s):  
Ying Zhou ◽  
Guiping Lin ◽  
Xueqin Bu ◽  
Lizhan Bai ◽  
Dongsheng Wen
Keyword(s):  
Heat Transfer ◽  
Experimental Study ◽  
Jet Impingement ◽  
Curvature Effects ◽  
Impingement Heat Transfer

A Mixing-Length Model for the Prediction of Convex Curvature Effects on Turbulent Boundary Layers

1984 ◽  
Vol 106 (1) ◽  
pp. 142-148 ◽  
Author(s):  
E. W. Adams ◽  
J. P. Johnston
Keyword(s):  
Heat Transfer ◽  
Layer Thickness ◽  
Boundary Layers ◽  
Turbulent Boundary Layers ◽  
Radius Of Curvature ◽  
Data Sets ◽  
Mixing Length ◽  
Flat Wall ◽  
Curvature Effects ◽  
Layer Thickness Ratio

A mixing-length model is developed for the prediction of turbulent boundary layers with convex streamwise curvature. For large layer thickness ratio, δ/R > 0.05, the model scales mixing length on the wall radius of curvature, R. For small δ/R, ordinary flat wall modeling is used for the mixing-length profile with curvature corrections, following the recommendations of Eide and Johnston [7]. Effects of streamwise change of curvature are considered; a strong lag from equilibrium is required when R increases downstream. Fifteen separate data sets were compared, including both hydrodynamic and heat transfer results. In this paper, six of these computations are presented and compared to experiment.

scholarly journals The Transient Liquid Crystal Technique: Influence of Surface Curvature and Finite Wall Thickness

2004 ◽  
Author(s):  
G. Wagner ◽  
M. Kotulla ◽  
P. Ott ◽  
B. Weigand ◽  
J. von Wolfersdorf
Keyword(s):  
Heat Transfer ◽  
Liquid Crystal ◽  
Flat Plate ◽  
Hollow Cylinder ◽  
Wall Thickness ◽  
Reduction Method ◽  
Radius Of Curvature ◽  
Test Model ◽  
Curvature Effects ◽  
Transient Liquid Crystal Technique

The transient liquid crystal technique is nowadays widely used for measuring the heat transfer characteristics in gas turbine applications. Usually, the assumption is made that the wall of the test model can be treated as a flat and semi-infinite solid. This assumption is correct as long as the penetration depth of the heat compared to the thickness of the wall and to the radius of curvature is small. However, those two assumptions are not always respected for measurements near the leading edge of a blade. This paper presents a rigorous treatment of the curvature and finite wall thickness effects. The unsteady heat transfer for a hollow cylinder has been investigated analytically and a data reduction method taking into account curvature and finite wall thickness effects has been developed. Experimental tests made on hollow cylinder models have been evaluated using the new reduction method as well as the traditional semi-infinite flat plate approach and a third method that approximately accounts for curvature effects. It has been found that curvature and finite thickness of the wall have in some cases a significant influence on the obtained heat transfer coefficient. The parameters influencing the accuracy of the semi-infinite flat plate model and the approximate curvature correction are determined and the domains of validity are represented.

Laminar-Transitional Convection From Repeated Ribs in a Channel

1992 ◽  
Vol 114 (1) ◽  
pp. 29-34 ◽  
Author(s):  
R. A. Wirtz ◽  
Weiming Chen
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Three Dimensional ◽  
Electronic Packages ◽  
Average Heat Transfer Coefficient ◽  
Pumping Power ◽  
Low Profile ◽  
Linear Correlations ◽  
Transfer Pressure ◽  
Wall Spacing

Velocimetry, heat transfer, and pressure drop experiments are reported for laminar/transitional air flow in a channel containing rectangular transverse ribs located along one channel wall. The geometry is intended to represent an array of low profile electronic packages. At fixed pumping power per unit channel volume, the heat transfer rate per unit volume is independent of rib-to-rib spacing and increases with decreasing wall-to-wall spacing. The fully developed, rib-average heat transfer coefficient is found to be linearly related to the maximum streamwise rms turbulence measured above the rib-tops. Linear correlations, in terms of a descriptor of the rms streamwise turbulence, are shown to unify heat transfer/pressure drop data for channels containing either two-or three-dimensional protrusions.

Magnetogasdynamic Flow and Heat Transfer in a Microchannel

2011 ◽  
Author(s):  
Huei Chu Weng
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Joule Heating ◽  
Electromagnetic Force ◽  
Gas Flow ◽  
Velocity Slip ◽  
Flow And Heat Transfer ◽  
Electric And Magnetic Field ◽  
Flow Through ◽  
Flow Drag

The presence of current flow in an electric and magnetic field results in electromagnetic force and joule heating. It is desirable to understand the roles of electromagnetic force and joule heating on gas microflow and heat transfer. In this study, a mathematical model is developed of the pressure-driven gas flow through a long isothermally heated horizontal planar microchannel in the presence of an external electric and magnetic field. The solutions for flow and thermal field and characteristics are derived analytically and presented in terms of dimensionless parameters. It is found that an electromagnetic driving force can be produced by a combined non-zero electric field and a negative magnetic field and results in an additional velocity slip and an additional flow drag. Also, a joule heating can be enhanced by an applied positive magnetic field and therefore results in an additional temperature jump and an additional heat transfer.

Numerical Simulation of Electromagnetic Field in the Cold Crucible

2013 ◽  
Author(s):  
Jinlong Zhang ◽  
Pengfei Li
Keyword(s):  
Heat Transfer ◽  
Electromagnetic Field ◽  
Induction Heating ◽  
Electromagnetic Force ◽  
Power Efficiency ◽  
Cooling Water ◽  
Joule Heat ◽  
Cold Crucible ◽  
Primary Problem ◽  
Frequency Power

SNPTRD was planning to employ cold crucible induction heating technique to investigate the corium pool heat transfer, using the UO2 and ZrO2 mixture as the simulated corium pool. Compared with the actual situation, the primary problem of the cold crucible induction heating was the additional introduction of electromagnetic field. To investigate the cold crucible applicability in simulating the corium pool heat transfer, the distribution of joule heat inside cold crucible and the magnitude of electromagnetic force were carried out. To be more suitable for heat transfer test research, the shape of cold crucible was changed to hemisphere, and the cooling water channels were set horizontally. The simulation results indicated that joule heat distribution would be more uniform with lower frequency power but considering power efficiency, there was only one best frequency. The magnitude of electromagnetic force can be ignored compared to the gravity on the natural convection research.

Sign in / Sign up

Export Citation Format

Share Document