Characteristics of Thermal–Hydraulic and Heat Transfer in Liquid Windowless Target of Accelerator Driven Subcritical

2018 ◽  
Vol 4 (3) ◽  
Author(s):  
Feng Wang ◽  
Qiang Wen ◽  
Xue Qin
Keyword(s):  
Heat Transfer ◽  
Morphological Characteristics ◽  
Transfer Characteristic ◽  
Structure Design ◽  
Liquid Lead ◽  
Target Area ◽  
Interface Morphology ◽  
Free Interface ◽  
Vof Model ◽  
Free Interfaces

In recent years, the morphological characteristics and stabilization methods of free interface in liquid windowless target become hot research topics in accelerator driven subcritical system (ADS). Based on the structure design of a certain windowless spallation target, computational fluid dynamics (CFD) software of CFX was used to simulate and analyze its free interface character. The method of k–ε turbulence, cavitation, and volume of fluid (VOF) model was used to study the flow characteristic of liquid Lead-Bismuth eutectic (LBE) alloy with cavitation phase change and to analyze the free interface morphology characteristics of coolant in the target area. It is concluded that the target region forms two stable free interfaces when fluid outlet pressure is in the range of 10–40 kPa and fluid entrance velocity is in the range of 0.5–1.2 m/s. The flow field near the free interface structure is complex. The vortex region appears, and the disorders in the vortex flow pattern lead to fluctuation of the free interface. After the study of stable free interface morphology establishing process, heat transfer characteristic of windowless target was further analyzed.

Characteristics of Thermal-Hydraulic and Heat Transfer in Liquid Windowless Target of ADS

2017 ◽  
Author(s):  
Feng Wang ◽  
Qiang Wen ◽  
Xue Qin
Keyword(s):  
Heat Transfer ◽  
Morphological Characteristics ◽  
Structure Design ◽  
Liquid Lead ◽  
Target Area ◽  
Interface Morphology ◽  
Target Region ◽  
Free Interface ◽  
Bismuth Alloy ◽  
Free Interfaces

In recent years, the morphological characteristics and stabilization methods of free interface in liquid windowless target become hot research topics in accelerator driven subcritical system (ADS). Based on the structure design of a certain windowless spallation target, CFX program was used to simulate and analyze its free interface character. The method of k-ε turbulence model, Cavitation model and VOF method were used to study the flow characteristic of liquid lead-bismuth alloy (LBE) with cavitation phase change and to analyze the free interface morphology characteristics of coolant in the target area. It is concluded that the target region form two stable free interfaces when fluid outlet pressure is in the range of 10000–40000Pa and fluid entrance velocity is in the range of 0.5–1.2m/s. The flow field near the free interface structure is complex. The vortex region appears, and the disorders in the vortex flow pattern leads to fluctuation of the free interface. After establishing stable free interface morphology, the heat transfer characteristics of windowless target was further analyzed.

Experimental Research on Heat Transfer Characteristic of Liquid Lead-Bismuth Eutectic Flowing in Annular Channel

2018 ◽  
Author(s):  
Fengjie Zhu ◽  
Junmei Wu ◽  
Leitai Shi ◽  
G. H. Su
Keyword(s):  
Heat Transfer ◽  
Friction Coefficient ◽  
Flow Rate ◽  
Heat Transfer Characteristic ◽  
Convection Heat Transfer ◽  
Annular Channel ◽  
Transfer Characteristic ◽  
Liquid Lead ◽  
Convection Heat ◽  
Gas Lift

Liquid lead-bismuth eutectic (LBE) has been studied as a new type of coolant for an accelerator driven sub-critical system (ADS). And the gas-lift pump has been used to enhance the circulation capacity of coolant in ADS instead of mechanical pumps due to its simpler mechanical structure and higher security. The purpose of this experiment is to study the circulation capacity enhancement by gas-lift technique and the flow and heat transfer characteristic of liquid LBE in an annular channel. The experimental results show that: gas-injection can significantly increase liquid LBE mass flow rate, but the growth of liquid LBE mass flow rate will be reduced when gas flow rate reaches a value; The friction coefficient of liquid LBE in an annular channel decreases with the increase of Re and is larger than that calculated by Blasius formula at the same Re. For the convection heat transfer of liquid LBE in an annular channel, the heat conduction term is dominant, and Nusselt number increases with the increase of Peclet number. The experimental correlations of friction coefficient and convection heat transfer of liquid LBE in annular channel were fitted based on experimental data and compared with those from literature.

The Study on Porous Media Phase Change Coupling Heat Transfer Model in Enclosed Metal Cavity

2015 ◽  
Vol 1120-1121 ◽  
pp. 1378-1384
Author(s):  
Run Hui Wu ◽  
Jia Qi Liu ◽  
Xin Liu ◽  
Ai Min Ren ◽  
Sheng Jun Zhang ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Phase Transition ◽  
Porous Medium ◽  
Heat Source ◽  
Phase Change ◽  
Heat Transfer Characteristic ◽  
Transfer Characteristic ◽  
High Energy ◽  
Transfer Model ◽  
Target Area

This thesis is aimed to the external instantaneous high energy heat source, according to enclosed metal cavity, porous medium in the cavity, porous media can by phase change heat transfer characteristic of variegated medium coupling state target’s special requirements in the field of aerospace, it is innovatively to put forward a kind of applicable to simulate sealed coupling target, under the condition of instant high energy heat source excitation, By heat source-metal cavity-porous medium—porous medium’s phase-changeable phase change process heat-transfer characteristic numerical calculation model-creation approach, in use of the metal cavity, in the porous medium incompressible flow phase transition of working medium’s heat energy conservation, momentum conservation and mass conservation principle, it is to establish analysis model of coupled heat transfer characteristics of multiple parts, in order to acquire the full target area of airtight coupling state targets, temperature field, pressure field, velocity field and phase change of phase transition of working medium characteristics change with time and space change numerical value to analog result. The study results points out: when the incentive heat source keep constant, the change rule of full target area temperature, pressure flow rate and phase change characteristic parameters is in conformity with theory of heat transfer medium. The heat transfer model can be popularized and applied to the optimization design of incentive heat source, and comprehensive performance optimization of enclosed coupling state objects.

Simulation on the Flow and Heat Transfer Characteristics of Confined Bubbles in Micro-Channels

2012 ◽  
Author(s):  
Qingming Liu ◽  
Björn Palm ◽  
Henryk Anglart
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Mass Flux ◽  
Phase Interface ◽  
Working Fluid ◽  
Initial Shape ◽  
Thin Film Evaporation ◽  
Flow And Heat Transfer ◽  
Vof Model ◽  
Micro Channels

3D simulations on confined bubbles in micro-channels with diameter of 1.24 mm were conducted. The working fluid is R134a with a mass flux range from 125kg/m2s to 375kg/m2s. The VOF model is chosen to capture the 2 phase interface while the geo-construction method was used to re-construct the 2-phase interface. A heated boundary wall with heat flux varying from 15kW/m2 to 102kW/m2 is supplied. The wall temperature was calculated. The effects of mass flux and heat flux are studied. The shape of the bubble was predicted by the simulation successfully and the results show that they are independent of the initial shape. Both thin film evaporation and micro convection enhance the heat transfer. However, the micro convection which is caused by bubble motion has greater contribution to the total heat transfer at the stage of bubble growth studied.

Heat transfer characteristic modelling and the effect of operating conditions on re-cooled cycle for a scramjet

2011 ◽  
Vol 115 (1164) ◽  
pp. 83-90 ◽  
Author(s):  
W. Bao ◽  
J. Qin ◽  
W. X. Zhou
Keyword(s):  
Heat Transfer ◽  
Heat Sink ◽  
Transfer Characteristic ◽  
Cooling Capacity ◽  
Sensitivity Study ◽  
Performance Model ◽  
Operating Conditions ◽  
Inlet Temperature ◽  
Fuel Flow ◽  
Temperature And Pressure

Abstract A re-cooled cycle has been proposed for a regeneratively cooled scramjet to reduce the hydrogen fuel flow for cooling. Upon the completion of the first cooling, fuel can be used for secondary cooling by transferring the enthalpy from fuel to work. Fuel heat sink (cooling capacity) is thus repeatedly used and fuel heat sink is indirectly increased. Instead of carrying excess fuel for cooling or seeking for any new coolant, the cooling fuel flow is reduced, and fuel onboard is adequate to satisfy the cooling requirement for the whole hypersonic vehicle. A performance model considering flow and heat transfer is build. A model sensitivity study of inlet temperature and pressure reveals that, for given exterior heating condition and cooling panel size, fuel heat sink can be obviously increased at moderate inlet temperature and pressure. Simultaneously the low-temperature heat transfer deterioration and Mach number constrains can also be avoided.

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