الفهرس 
IntroductionOnly 14 pages are availabe for public view
 |  | from | 181 |  |  |
| | | from | 181 | | |
Abstract
An experimental and numerical investigations had been conducted to study the convection heat transfer in air gap between two horizontal concentric and eccentric rotating cylinders. The effects of cylinder rotation, heat flux, eccentricity, aspect ratio, and the thickness of the air gap are investigated. The numerical study is conducted for laminar flow natural convection. The temperature distribution and hydrodynamics flow field in annulus were predicted. The numerical simulations for the problem were carried out by using commercial CFD (Computational Fluif Dynamics) code. The governing equations describing the fluid flow were solved using a commercial package FLUENT 6.3.26. The effects of eccentricity as well as other parameters such as aspect ratio and heat flux on the flow and heat transfer characteristics were investigated numerically. The numerical simulations covered ranged of eccentricity from 0 to 1.2, radius ratio from 1.2 to 4.6, the rotation Reynolds number ranged from 0 to 820 and heat flux ranged from 50 to 1140 W/m2. To validate the present numerical results, an experimental test rig was designed and constructed to achieve this objective. The measurements were performed for temperature distribution, gap between the two cylinders, heat flux and rotation through all the experimental runs. Heat transfer rates (expressed in Nusselt numbers) had computed for Rayleigh number ranged from 3x 103 to 1.6x 105, rotation Reynolds number ranged from 0 to 820, eccentricity ranged from 0 to 1.2, aspect ratio ranged from 29 to 71.5, radiI ratio ranged from 1.9 to 4050and heat flux ranged from 100 to 1140 W/M2. The present work had been done for the case of stationary annulus. The results obtained show quite agreement with the published data in the available literature of maximum deviation of = 5 %. The results were presented in form of Nusselt number, rotation Reynolds number, Rayleigh number, eccentricity, aspect ratio, and radio ratio. The results were show that the average Nusselt number increases with the increase of the eccentricity of the inner cylinder, rotation Reynolds number, radius ratio and Rayleigh number. The average Nusselt numbers obtained from the present experimental measurements are compared with those obtained from the CFD code. Both the fluid flow and heat transfer characteristics for different operating and geometric conditions are illustrated. Streamlines and isothermal contour lines obtained from the CFD code are indicated. Comparison of the present numerical and experimental results with the available published data shows good agreement. Two correlations in a form of Nusselt number as a function of dimensionless aspect ratio (As), dimensionless radius ratio (R), rotation Reynolds number (Rea), Rayleigh number (Ra) and eccentricity are deduced for stationary and rotating conditions are deduced based on the experimental measurements with average deviation = 6.5%. An experimental and numerical investigations had been conducted to study the convection heat transfer in air gap between two horizontal concentric and eccentric rotating cylinders. The effects of cylinder rotation, heat flux, eccentricity, aspect ratio, and the thickness of the air gap are investigated. The numerical study is conducted for laminar flow natural convection. The temperature distribution and hydrodynamics flow field in annulus were predicted. The numerical simulations for the problem were carried out by using commercial CFD (Computational Fluif Dynamics) code. The governing equations describing the fluid flow were solved using a commercial package FLUENT 6.3.26. The effects of eccentricity as well as other parameters such as aspect ratio and heat flux on the flow and heat transfer characteristics were investigated numerically. The numerical simulations covered ranged of eccentricity from 0 to 1.2, radius ratio from 1.2 to 4.6, the rotation Reynolds number ranged from 0 to 820 and heat flux ranged from 50 to 1140 W/m2. To validate the present numerical results, an experimental test rig was designed and constructed to achieve this objective. The measurements were performed for temperature distribution, gap between the two cylinders, heat flux and rotation through all the experimental runs. Heat transfer rates (expressed in Nusselt numbers) had computed for Rayleigh number ranged from 3x 103 to 1.6x 105, rotation Reynolds number ranged from 0 to 820, eccentricity ranged from 0 to 1.2, aspect ratio ranged from 29 to 71.5, radiI ratio ranged from 1.9 to 4050and heat flux ranged from 100 to 1140 W/M2. The present work had been done for the case of stationary annulus. The results obtained show quite agreement with the published data in the available literature of maximum deviation of = 5 %. The results were presented in form of Nusselt number, rotation Reynolds number, Rayleigh number, eccentricity, aspect ratio, and radio ratio. The results were show that the average Nusselt number increases with the increase of the eccentricity of the inner cylinder, rotation Reynolds number, radius ratio and Rayleigh number. The average Nusselt numbers obtained from the present experimental measurements are compared with those obtained from the CFD code. Both the fluid flow and heat transfer characteristics for different operating and geometric conditions are illustrated. Streamlines and isothermal contour lines obtained from the CFD code are indicated. Comparison of the present numerical and experimental results with the available published data shows good agreement. Two correlations in a form of Nusselt number as a function of dimensionless aspect ratio (As), dimensionless radius ratio (R), rotation Reynolds number (Rea), Rayleigh number (Ra) and eccentricity are deduced for stationary and rotating conditions are deduced based on the experimental measurements with average deviation = 6.5% An experimental and numerical investigations had been conducted to study the convection heat transfer in air gap between two horizontal concentric and eccentric rotating cylinders. The effects of cylinder rotation, heat flux, eccentricity, aspect ratio, and the thickness of the air gap are investigated. The numerical study is conducted for laminar flow natural convection. The temperature distribution and hydrodynamics flow field in annulus were predicted. The numerical simulations for the problem were carried out by using commercial CFD (Computational Fluif Dynamics) code. The governing equations describing the fluid flow were solved using a commercial package FLUENT 6.3.26. The effects of eccentricity as well as other parameters such as aspect ratio and heat flux on the flow and heat transfer characteristics were investigated numerically. The numerical simulations covered ranged of eccentricity from 0 to 1.2, radius ratio from 1.2 to 4.6, the rotation Reynolds number ranged from 0 to 820 and heat flux ranged from 50 to 1140 W/m2 To validate the present numerical results, an experimental test rig was designed and constructed to achieve this objective. The measurements were performed for temperature distribution, gap between the two cylinders, heat flux and rotation through all the experimental runs. Heat transfer rates (expressed in Nusselt numbers) had computed for Rayleigh number ranged from 3x 103 to 1.6x 105, rotation Reynolds number ranged from 0 to 820, eccentricity ranged from 0 to 1.2, aspect ratio ranged from 29 to 71.5, radiI ratio ranged from 1.9 to 4050and heat flux ranged from 100 to 1140 W/M2. The present work had been done for the case of stationary annulus. The results obtained show quite agreement with the published data in the available literature of maximum deviation of = 5 %. The results were presented in form of Nusselt number, rotation Reynolds number, Rayleigh number, eccentricity, aspect ratio, and radio ratio. The results were show that the average Nusselt number increases with the increase of the eccentricity of the inner cylinder, rotation Reynolds number, radius ratio and Rayleigh number. The average Nusselt numbers obtained from the present experimental measurements are compared with those obtained from the CFD code. Both the fluid flow and heat transfer characteristics for different operating and geometric conditions are illustrated. Streamlines and isothermal contour lines obtained from the CFD code are indicated. Comparison of the present numerical and experimental results with the available published data shows good agreement. Two correlations in a form of Nusselt number as a function of dimensionless aspect ratio (As), dimensionless radius ratio (R), rotation Reynolds number (Rea), Rayleigh number (Ra) and eccentricity are deduced for stationary and rotating conditions are deduced based on the experimental measurements with average deviation.