Experiments and numerical simulations of flow field and heat transfer coefficients inside an autoclave model

2017 ◽  
Author(s):  
T. Ghamlouch ◽  
S. Roux ◽  
J.-L. Bailleul ◽  
N. Lefèvre ◽  
V. Sobotka
Keyword(s):  
Heat Transfer ◽  
Flow Field ◽  
Numerical Simulations ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients

Natural Convection Heat Transfer From Horizontal Rectangular Fin Arrays

1967 ◽  
Vol 89 (1) ◽  
pp. 32-38 ◽  
Author(s):  
F. Harahap ◽  
H. N. McManus
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Flow Field ◽  
Convection Heat Transfer ◽  
Natural Convection Heat Transfer ◽  
Convection Heat ◽  
Transfer Coefficients ◽  
Average Heat ◽  
Heat Transfer Coefficients

Average heat-transfer coefficients are presented for fin arrays positioned with the base oriented horizontally. The flow field associated with the natural convection from the fin arrays was investigated and used as a model to find parameters to generalize the data. The proposed correlation overcomes the inadequacy of parameters available previously for horizontal rectangular fins.

scholarly journals Gas-Solid Heat Transfer Computation from Particle-Resolved Direct Numerical Simulations

Fluids ◽  
2021 ◽  
Vol 7 (1) ◽  
pp. 15
Author(s):  
Mohamed-Amine Chadil ◽  
Stéphane Vincent ◽  
Jean-Luc Estivalèzes
Keyword(s):  
Heat Transfer ◽  
Numerical Simulations ◽  
Penalty Method ◽  
Accurate Estimate ◽  
Second Order ◽  
High Order ◽  
Direct Numerical Simulations ◽  
Transfer Coefficients ◽  
Carrier Fluid ◽  
Heat Transfer Coefficients

Particle-Resolved simulations (PR-DNS) have been conducted using a second order implicit Viscous Penalty Method (VPM) to study the heat transfer between a set of particles and an incompressible carrier fluid. A Lagrange extrapolation coupled to a Taylor interpolation of a high order is utilized to the accurate estimate of heat transfer coefficients on an isolated sphere, a fixed Faced-Centered Cubic array of spheres, and a random pack of spheres. The simulated heat transfer coefficients are compared with success to various existing Nusselt laws of the literature.

scholarly journals Augmentation of Stagnation Region Heat Transfer due to Turbulence From a DLN Can Combustor

2000 ◽  
Author(s):  
G. James Van Fossen ◽  
Ronald S. Bunker
Keyword(s):  
Heat Transfer ◽  
Flow Field ◽  
Test Section ◽  
Leading Edge ◽  
Scale Model ◽  
Transfer Coefficients ◽  
Stagnation Region ◽  
Heat Transfer Coefficients ◽  
Heat Transfer Augmentation ◽  
Made In

Heat transfer measurements have been made in the stagnation region of a flat plate with a circular leading edge. Electrically heated aluminum strips placed symmetrically about the leading edge stagnation region were used to measure spanwise averaged heat transfer coefficients. The maximum Reynolds number obtained, based on leading edge diameter, was about 100,000. The model was immersed in the flow field downstream of an approximately half scale model of a can-type combustor from a low NOx, ground based power-generating turbine. The tests were conducted with room temperature air; no fuel was added. Room air flowed into the combustor through six vane type fuel/air swirlers. The combustor can contained no dilution holes. The fuel/air swirlers all swirled the incoming airflow in a counter clockwise direction (facing downstream). A 5-hole probe flow field survey in the plane of the model stagnation point showed the flow was one big vortex with flow angles up to 36° at the outer edges of the rectangular test section. Hot wire measurements showed test section flow had very high levels of turbulence, around 28.5%, and had a relatively large axial-length scale-to-leading edge diameter ratio of 0.5. X-wire measurements showed the turbulence to be nearly isotropic. Stagnation heat transfer augmentation over laminar levels was around 77% and was about 14% higher than predicted by a previously developed correlation for isotropic grid generated turbulence.

Heat Transfer Measurements and Numerical Simulations in the Cooling of a Circular Cylinder by a Slot Jet of Air

2003 ◽  
Author(s):  
F. Gori ◽  
I. Petracci
Keyword(s):  
Heat Transfer ◽  
Circular Cylinder ◽  
Numerical Simulations ◽  
Convective Heat Transfer ◽  
Reynolds Numbers ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
Nusselt Numbers ◽  
Commercial Code ◽  
Convective Heat Transfer Coefficients

The present paper reports heat transfer measurements on a circular cylinder, electrically heated, and cooled by a slot jet of air. The diameter of the cylinder is equal to the slot height. Temperature measurements in five positions along the circumference of the circular cylinder, allow the evaluation of the convective heat transfer coefficients or Nusselt numbers at several Reynolds numbers. The Nusselt numbers are compared with the corresponding results in uniform flow around a circular cylinder. The experiments have been performed at several distances from the slot jet exit and different Reynolds numbers. Numerical simulations have been carried out with a commercial code.

Forced Convective Cooling Enhancement of Electronic Package Configurations Through Self-Sustained Oscillatory Flows

1993 ◽  
Vol 115 (4) ◽  
pp. 356-365 ◽  
Author(s):  
J. S. Nigen ◽  
C. H. Amon
Keyword(s):  
Heat Transfer ◽  
Flow Field ◽  
Printed Circuit Board ◽  
Local Heat Transfer ◽  
Thermal Design ◽  
Circuit Board ◽  
Electronic Packages ◽  
Transfer Coefficients ◽  
Electronic Package ◽  
Heat Transfer Coefficients

Two-dimensional arrangements of electronic packages surface mounted to a printed circuit board represent grooved-channel geometries. For a certain range of Reynolds numbers, these geometries excite and sustain instabilities that are normally damped in planar Poiseuille flows. This results in a bifurcation to a self-sustained oscillatory state, which improves mixing and thereby enhances convective heat transport. Numerical simulations of the flow field and heat transfer characteristics of oscillatory and nonoscillatory flows for five grooved channels are presented. Additionally, the numerically obtained flow field corresponding to a suspended electronic package is analyzed. The extent of heat transfer enhancement is gauged through direct comparison to results corresponding to the steady-flow regime. Local heat transfer coefficients are determined and used to calculate the temperature distribution within a surface-mounted package. Moreover, the importance of using locally-defined instead of spatially-averaged heat transfer coefficients for thermal design and analysis of electronic packages is discussed.

scholarly journals Simulations of Hot-Gas Flow in Internally Cooled Cascade of Turbine Vanes

2019 ◽  
Vol 26 (2) ◽  
pp. 151-158
Author(s):  
Janusz Sznajder
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Numerical Simulations ◽  
Gas Flow ◽  
Turbulence Models ◽  
Turbulence Energy ◽  
Transfer Coefficients ◽  
Cooling Channels ◽  
Heat Transfer Coefficients ◽  
Outlet Flow

Abstract An experiment in cooling of gas turbine nozzle guide vanes was modelled numerically with a conjugate viscous-flow and solid-material heat conduction solver. The nozzle vanes were arranged in a cascade and operated in high-pressure, hot-temperature conditions, typical for first turbine stage in a flow of controlled-intensity, artificially-generated turbulence. The vane cooling was internal, accomplished by 10 channels in each vane with cooling-air flow. Numerical simulations of the experiment were conducted applying two turbulence models of the k-omega family: k-omega-SST and Transition SST implemented in the ANSYS Fluent solver. Boundary conditions for the simulations were set based on conditions of experiment: total pressures and total temperature on inlet to cascade, static pressure on the outlet of the cascade and heat flux on the surface of cooling channels. The values of heat flux on the surface of cooling channels were evaluated based on Nusselt numbers obtained from experiment and varied in time until steady-state conditions were obtained. Two test cases, one with subcritical outlet flow, and another one, with supercritical outlet flow were simulated. The result of experiment – distributions of pressure, surface temperature, and heat transfer coefficients on the vane external surface were compared to results of numerical simulations. Sensitivity of the vane surface temperatures and heat transfer coefficients to turbulence models and to boundary-condition values of parameters of turbulence models: turbulence energy and specific dissipation of turbulence energy was also studied.

scholarly journals Fundamental Evaluation of Thermal Switch Based on Ionic Wind

Energies ◽  
2019 ◽  
Vol 12 (15) ◽  
pp. 2963 ◽  
Author(s):  
Keiichiro Yoshida
Keyword(s):  
Heat Transfer ◽  
Numerical Simulations ◽  
Waste Heat ◽  
Copper Plate ◽  
Ionic Wind ◽  
Transfer Coefficients ◽  
Heat Management ◽  
Heat Transfer Coefficients ◽  
Thermal Switch ◽  
Basic Characteristics

A significant amount of thermal energy (mainly under 200 °C) is wasted in the world. To utilize the waste heat, efficient heat management and thermal switching is required. The basic characteristics of a thermal switch that controls the flow of heat by switching on/off the ionic wind is discussed in this study. The study was conducted through experiments and numerical simulations. A heater made of aluminum block maintained at 100 °C was used as a heat source, and the rate of heat flow to a copper plate placed over it was measured. Ionic wind was induced by corona discharge with a needle placed on the heater. The ratio of heat transfer coefficients was obtained in the range of 3–4, with an energy efficiency of around 10. The heat flux at this condition was approximately 400 W/m2. The numerical simulations indicate that the heat transfer is enhanced by ionic winds, and the results were found to corroborate well with the experimental ones.

Measurement of Heat Transfer Coefficient Distributions and Flow Field in a Model of a Turbine Blade Cooling Passage With Tangential Injection

2006 ◽  
Author(s):  
John P. C. W. Ling ◽  
Peter T. Ireland ◽  
Neil W. Harvey
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Flow Field ◽  
Transfer Coefficient ◽  
Cooling System ◽  
High Heat ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
High Heat Transfer ◽  
Cooling Passage

In certain regions of turbine aerofoils, cooling system designers need to cool the blades with convection systems that provide high heat transfer coefficients. The present research has investigated a circular cooling passage with tangential injection suitable for a blade leading edge. The heat transfer coefficients are measured using the conventional transient heat transfer, liquid crystal technique. The results are compared to the data from steady state experiments performed by Hedlund et al. [1]. The cooling system performance is compared in detail to average data from earlier tangential injection experiments and to local heat transfer coefficient expected from a normal impingement system. The vortex flow field was also studied by numerical prediction and near-wall velocity measurements. The investigation of the flow structure has led to understanding of flow mechanisms responsible for the high heat transfer coefficient. The vortex flow field was also investigated using computational fluid dynamics and with hot wire anemometry. The latter near wall measurements were combined with the law of the wall and Colburn analogy to validate the flow and heat transfer measurements.

scholarly journals Augmentation of Stagnation Region Heat Transfer Due to Turbulence From a DLN Can Combustor

2000 ◽  
Vol 123 (1) ◽  
pp. 140-146 ◽  
Author(s):  
G. James Van Fossen ◽  
Ronald S. Bunker
Keyword(s):  
Heat Transfer ◽  
Flow Field ◽  
Test Section ◽  
Leading Edge ◽  
Scale Model ◽  
Transfer Coefficients ◽  
Stagnation Region ◽  
Heat Transfer Coefficients ◽  
Heat Transfer Augmentation ◽  
Made In

Heat transfer measurements have been made in the stagnation region of a flat plate with a circular leading edge. Electrically heated aluminum strips placed symmetrically about the leading edge stagnation region were used to measure spanwise-averaged heat transfer coefficients. The maximum Reynolds number obtained, based on leading edge diameter, was about 100,000. The model was immersed in the flow field downstream of an approximately half-scale model of a can-type combustor from a low NOx, ground-based power-generating turbine. The tests were conducted with room temperature air; no fuel was added. Room air flowed into the combustor through six vane-type fuel/air swirlers. The combustor can contained no dilution holes. The fuel/air swirlers all swirled the incoming airflow in a counterclockwise direction (facing downstream). A five-hole probe flow field survey in the plane of the model stagnation point showed the flow was one big vortex with flow angles up to 36 deg at the outer edges of the rectangular test section. Hot-wire measurements showed test section flow had very high levels of turbulence, around 28.5 percent, and had a relatively large axial-length scale-to-leading edge diameter ratio of 0.5. X-wire measurements showed the turbulence to be nearly isotropic. Stagnation heat transfer augmentation over laminar levels was around 77 percent and was about 14 percent higher than predicted by a previously developed correlation for isotropic grid-generated turbulence.

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