Computational Analyses of Flow and Heat Transfer at 60° Position of 180° Curved Duct of Square Cross-Section

2020 ◽  
Vol 26 ◽  
pp. 53-62
Author(s):  
Mourad Mokeddem ◽  
Houssem Laidoudi ◽  
Mohamed Bouzit
Keyword(s):  
Heat Transfer ◽  
Flow Behavior ◽  
Angular Position ◽  
Three Dimensions ◽  
Dean Number ◽  
Cross Sectional ◽  
Thermal Buoyancy ◽  
Flow And Heat Transfer ◽  
Axial Velocity Profile ◽  
Computational Analyses

3D computational analyses are achieved to predict seriously the influences of thermal buoyancy strength and Dean number on Dean vortices, flow behavior and the rate heat transfer through 180° curved channel of square cross-sectional form. The work shows many results, so this paper emphasizes only on the results of 60° cross-sectional position of the bend duct. The principal partial equations of continuity, momentum and energy are considering in three dimensions under the following assumptions: flow is incompressible and laminar, and it is solved in steady-state. The aforementioned equations are subjected to suitable boundary conditions under following range as: Dean number of De = 125 to 150, Richardson number of Ri = 0 to 2 at fixed value of Prandtl number Pr = 1. The principal results of this work are illustrated as streamline and isotherm contours to draw to flow patterns and temperature distributions respectively. The axial velocity profile is shown versus above conditions, the local Nusselt number is also presented along the wall of 60° cross-sectional position. The results show that the thermal buoyancy can balance the effect of centrifugal force of fluid particles at the angular position of 60°.

3D Simulation of Dean Vortices at 30° Position of 180° Curved Duct of Square Cross-Section under Opposing Buoyancy

2018 ◽  
Vol 389 ◽  
pp. 153-163 ◽  
Author(s):  
Mourad Mokeddem ◽  
Houssem Laidoudi ◽  
Mohamed Bouzit
Keyword(s):  
Cross Section ◽  
Richardson Number ◽  
Three Dimensions ◽  
Governing Equations ◽  
Dean Number ◽  
Thermal Buoyancy ◽  
Dean Vortices ◽  
Flow And Heat Transfer ◽  
Curved Duct ◽  
Physical Phenomena

3D numerical simulations are performed to analyze correctly the effect of opposing thermal buoyancy and Dean number on Dean vortices, fluid flow and heat transfer through 180° curved duct of square cross-section. Due to tremendous found results, this works emphasizes only at the position 30° of the bend portion. The governing equations involving momentum, continuity and energy are solved in three dimensions under these assumptions: the flow is laminar, steady-state and incompressible. The present study is investigated in the range of these conditions: Dean number of De = 125 to 150, Richardson number of Ri = 0 to 2 at Pr = 1. The principal obtained results are represented in forms of streamlines and isotherms to analyze and to discuss the found physical phenomena. The local Nusselt number along the wall of square cross-section is also computed and presented. The main found point is that the opposing thermal buoyancy has a tendency to eliminate the effect of centrifugal force at the position 30° of bend portion of 180° curved duct.

Simulation of Non Newtonian Power-Law Fluid Flows and Mixed Convection Heat Transfer inside of Curved Duct

2017 ◽  
Vol 378 ◽  
pp. 113-124 ◽  
Author(s):  
Bouzit Fayçal ◽  
Houssem Laidoudi ◽  
Mohamed Bouzit
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Rate ◽  
Power Law ◽  
Transfer Rate ◽  
Richardson Number ◽  
Flow Behavior ◽  
Thermal Buoyancy ◽  
Flow And Heat Transfer ◽  
Curved Duct ◽  
Power Law Fluids

A two-dimensional numerical simulation is carried out to understand the combined effects of thermal buoyancy strength and rheological flow behavior of non Newtonian power-law fluids on laminar flow and heat transfer rate through a 180° curved duct. The governing equations including the full Navier-Stokes, the continuity and the energy are solved using the commercial code ANSYS-CFX. The numerical results are presented and discussed for the range of conditions as: Re = 40 to 1000, Ri = 0 to 1 and n = 0.4 to 1.2 for fixed value of Prandt number of Pr = 1. In order to analyze the obtained results, the representative streamlines and isotherm patterns are presented. The average Nusselt number of the inner and outer walls of duct is computed to determine the role of Reynolds number, Richardson number and power-law index on flow and heat transfer. It is found that increase in Richardson number creates alternative vortices on duct walls. Moreover, the alternative vortices enhance the heat transfer rate for shear thinning, Newtonian and shear thickening fluids.

Experimental Measurements of the Flow and Heat Transfer of a Square Jet Impinging on an Array of Square Pin Fins

2002 ◽  
Author(s):  
Johnny S. Issa ◽  
Alfonso Ortega
Keyword(s):  
Heat Transfer ◽  
Thermal Resistance ◽  
Flow Behavior ◽  
Jet Impingement ◽  
Tip Clearance ◽  
Heat Sinks ◽  
Clearance Ratio ◽  
Cross Sectional ◽  
Pressure Loss Coefficient ◽  
Air Jet

An experimental investigation was conducted to explore the flow behavior, pressure drop, and heat transfer due to free air jet impingement on square in-line pin fin heat sinks (PFHS) mounted on a plane horizontal surface. A parametrically consistent set of aluminum heat sinks with fixed base dimension of 25 × 25 mm was used, with pin heights varying between 12.5 mm and 22.5 mm, and fin thickness between 1.5 mm and 2.5 mm. A 6:1 contracting nozzle having a square outlet cross sectional area of 25 × 25 mm was used to blow air at ambient temperature on the top of the heat sinks with velocities varying from 2 to 20 m/s. The ratio of the gap between the jet exit and the pin tips to the pin height, the so-called tip clearance ratio, was varied from 0 (no tip clearance) to 1. The stagnation pressure recovered at the center of the heat sink was higher for tall pins than short pins. The pressure loss coefficient showed a little dependence on Re, increased with increasing pin density, and pin diameter, and decreased with increasing pin height and clearance ratio. The overall base-to-ambient thermal resistance decreased with increasing Re number, pin density and pin diameter. Surprisingly, the dependence of the thermal resistance on the pin height and clearance ratio was shown to be mild at low Re, and to vanish at high Re number.

Numerical Prediction of Flow and Heat Transfer in a Parallel Plate Channel With Staggered Fins

1987 ◽  
Vol 109 (1) ◽  
pp. 25-30 ◽  
Author(s):  
K. M. Kelkar ◽  
S. V. Patankar
Keyword(s):  
Heat Transfer ◽  
Local Heat Transfer ◽  
Periodic Variation ◽  
Local Heat ◽  
Temperature Fields ◽  
Parallel Plates ◽  
Constant Property ◽  
Cross Sectional ◽  
Flow And Heat Transfer ◽  
Order Of Magnitude

Fluid flow and heat transfer in two-dimensional finned passages were analyzed for constant property laminar flow. The passage is formed by two parallel plates to which fins are attached in a staggered fashion. Both the plates are maintained at a constant temperature. Streamwise periodic variation of the cross-sectional area causes the flow and temperature fields to repeat periodically after a certain developing length. Computations were performed for different values of the Reynolds number, the Prandtl number, geometric parameters, and the fin-conductance parameter. The fins were found to cause the flow to deflect significantly and impinge upon the opposite wall so as to increase the heat transfer significantly. However, the associated increase in pressure drop was an order of magnitude higher than the increase in heat transfer. Streamline patterns and local heat transfer results are presented in addition to the overall results.

scholarly journals UPWARD FLOW AND HEAT TRANSFER AROUND TWO HEATED CIRCULAR CYLINDERS IN SQUARE DUCT UNDER AIDING THERMAL BUOYANCY

2020 ◽  
Vol 14 (1) ◽  
pp. 113-123
Author(s):  
H. Laidoudi
Keyword(s):  
Heat Transfer ◽  
Convection Heat Transfer ◽  
Circular Cylinders ◽  
Upward Flow ◽  
Square Duct ◽  
Thermal Buoyancy ◽  
Flow And Heat Transfer ◽  
Ansys Cfx ◽  
Commercial Code ◽  
Physical Phenomena

This paper presents a numerical investigation of mixed convection heat transfer around a pair of identical circular cylinders placed in side-by-side arrangement inside a square cavity of single inlet and outlet ports. The investigation provided the analysis of gradual effect of aiding thermal buoyancy on upward flow around cylinders and its effect on heat transfer rate. For that purpose, the governing equations involving continuity, momentum and energy are solved using the commercial code ANSYS-CFX. The distance between cylinders is fixed with half-length of cavity. The simulation is assumed to be in laminar, steady, incompressible flow within range of following conditions: Re = 1 to 40, Ri = 0 to 1 at Pr = 0.71. The main obtained results are shown in the form of streamline and isotherm contours in order to interpret the physical phenomena of flow and heat transfer. The average Nusselt number is also computed and presented. It was found that increase in Reynolds number and/or Richardson number increases the heat transfer. Also, aiding thermal buoyancy creates new form of counter-rotating zones between cylinders.

Numerical Investigation of Mixed Convection Heat Transfer in Steady Flow Past a Row of Three Square Cylinders

2018 ◽  
Vol 389 ◽  
pp. 164-175
Author(s):  
Houssem Laidoudi ◽  
Bilal Blissag ◽  
Mohamed Bouzit
Keyword(s):  
Heat Transfer ◽  
Fluid Flow ◽  
Mixed Convection ◽  
Convection Heat Transfer ◽  
Convection Heat ◽  
Thermal Buoyancy ◽  
Flow And Heat Transfer ◽  
Square Cylinders ◽  
Laminar Mixed Convection ◽  
Mixed Convection Heat Transfer

In this paper, the numerical simulations of laminar mixed convection heat transfer from row of three isothermal square cylinders placed in side-by-side arrangement are carried out to understand the behavior of fluid flow around those cylinders under gradual effect of thermal buoyancy and its effect on the evacuation of heat energy. The numerical results are presented and discussed for the range of these conditions: Re = 10 to 40, Ri = 0 to 2 at fixed value of Prandtl number of Pr = 1 and at fixed geometrical configuration. In order to analyze the effect of thermal buoyancy on fluid flow and heat transfer characteristics the main results are illustrated in terms of streamline and isotherm contours. The total drag coefficient as well as average Nusselt number of each cylinder are also computed to determine exactly the effect of buoyancy strength on hydrodynamic force and heat transfer evacuation of each cylinder.

Modeling of the Flow and Heat Transfer in Micro Heat Pipes

2004 ◽  
Author(s):  
C. B. Sobhan ◽  
G. P. (Bud) Peterson
Keyword(s):  
Heat Transfer ◽  
Heat Pipe ◽  
Heat Pipes ◽  
Radius Of Curvature ◽  
Vapor Flow ◽  
Axial Distribution ◽  
Cross Sectional ◽  
Flow And Heat Transfer ◽  
Physical Phenomena ◽  
Micro Heat Pipes

The fluid flow and heat transfer characteristics of micro heat pipes are analyzed theoretically, in order to understand the physical phenomena and quantify the influence of various parameters on overall thermal performance of these devices. A one-dimensional model is utilized to solve the governing equations for the liquid/vapor flow and the heat transfer in the heat pipe channel. Variations in the liquid and vapor cross-sectional areas along the axial length of the heat pipe are included and the equations are solved using an implicit finite difference scheme. Appropriate models for fluid friction in small passages with varying cross-sectional areas have been incorporated to yield the axial distribution of the meniscus radius of curvature and the velocity, temperature and pressure in both the liquid and the vapor phases. Using this information, the effective thermal conductivity of the micro heat pipe is modeled, and parametric studies are performed by changing the heat load and cooling rate. The results of the analysis are discussed and compared with other theoretical models and experimental results found in the literature. By so doing, this analysis provides greater insight into the physical phenomena of flow and heat transfer in micro heat pipes and identifies a methodology for optimizing the design of these devices.

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