Analysis of turbulent wall jet impingement onto a moving heated body

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Hakan Coşanay ◽  
Hakan F. Öztop ◽  
Muhammed Gür ◽  
Eda Bakır
Keyword(s):  
Heat Transfer ◽  
Turbulent Flow ◽  
Jet Impingement ◽  
Wall Jet ◽  
Content Type ◽  
Moving Wall ◽  
Jet Cooling ◽  
Flow And Heat Transfer ◽  
Heated Body ◽  
Turbulent Wall

Purpose The purpose of this study is to make a numerical analysis of a wall jet with a moving wall attached with a heated body. The hot body is cooled via impinging wall jet. Thus, a jet cooling problem is modeled. The Reynolds number is taken in three different values between 5 × 103 ≤ Re ≤ 15 × 103. The h/H ratio for each value of the Re number was taken as 0.02, 0.04 and 0.0, respectively. Design/methodology/approach Two-dimensional impinged wall jet problem onto a moving body on a conveyor is numerically studied. The heated body is inserted onto an adiabatic moving wall, and it moves in +x direction with the wall. Governing equations for turbulent flow are solved by using the finite element method via analysis and system Fluent R2020. A dynamic mesh was produced to simulate the moving hot body. Findings The obtained results showed that the heat transfer (HT) is decreased with distance between the jet outlet and the jet inlet. The best HT occurred for the parameters of h/H = 0.02 and Re = 15 × 103. Also, HT can be controlled by changing the h/H ratio as a passive method. Originality/value Originality of this work is to make an analysis of turbulent flow and heat transfer for wall jet impinging onto a moving heated body.

Constrained large-eddy simulation of turbulent flow and heat transfer in a stationary ribbed duct

2016 ◽  
Vol 26 (3/4) ◽  
pp. 1069-1091 ◽  
Author(s):  
Zhou Jiang ◽  
Zuoli Xiao ◽  
Yipeng Shi ◽  
Shiyi Chen
Keyword(s):  
Heat Transfer ◽  
Large Eddy Simulation ◽  
Turbulent Flow ◽  
Thermodynamic Quantities ◽  
Detached Eddy Simulation ◽  
Square Duct ◽  
Content Type ◽  
Eddy Simulation ◽  
Flow And Heat Transfer ◽  
Large Eddy

Purpose – The knowledge about the heat transfer and flow field in the ribbed internal passage is particularly important in industrial and engineering applications. The purpose of this paper is to identify and analyze the performance of the constrained large-eddy simulation (CLES) method in predicting the fully developed turbulent flow and heat transfer in a stationary periodic square duct with two-side ribbed walls. Design/methodology/approach – The rib height-to-duct hydraulic diameter ratio is 0.1 and the rib pitch-to-height ratio is 9. The bulk Reynolds number is set to 30,000, and the bulk Mach number of the flow is chosen as 0.1 in order to keep the flow almost incompressible. The CLES calculated results are thoroughly assessed in comparison with the detached-eddy simulation (DES) and traditional large-eddy simulation (LES) methods in the light of the experimentally measured data. Findings – It is manifested that the CLES approach can predict both aerodynamic and thermodynamic quantities more accurately than the DES and traditional LES methods. Originality/value – This is the first time for the CLES method to be applied to simulation of heat and fluid flow in this widely used geometry.

Numerical modeling of Glauert type exponentially decaying wall jet flows of nanofluids using Tiwari and Das’ nanofluid model

2019 ◽  
Vol 29 (3) ◽  
pp. 1010-1038 ◽  
Author(s):  
Amin Jafarimoghaddam ◽  
Ioan Pop
Keyword(s):  
Heat Transfer ◽  
Numerical Modeling ◽  
Differential Equations ◽  
Design Methodology ◽  
Analytic Solution ◽  
Jet Flows ◽  
Wall Jet ◽  
Content Type ◽  
Flow And Heat Transfer ◽  
Wall Jet Flow

Purpose The purpose of this study is to present a simple analytic solution to wall jet flow of nanofluids. The concept of exponentially decaying wall jet flows proposed by Glauert (1956) is considered. Design/methodology/approach A proper similarity variables are used to transform the system of partial differential equations into a system of ordinary (similarity) differential equations. This system is then solved analytically. Findings Dual solutions are found and a stability analysis has been done. These solutions show that the first solution is physically realizable, whereas the second solution is not practicable. Originality/value The present results are original and new for the study of fluid flow and heat transfer over a static permeable wall, as they successfully extend the problem considered by Glauert (1956) to the case of nanofluids.

Fluid flow and heat transfer for a particle-laden gas modeled as a two-phase turbulent flow

2018 ◽  
Vol 28 (8) ◽  
pp. 1866-1891 ◽  
Author(s):  
John Gorman ◽  
Eph Sparrow
Keyword(s):  
Heat Transfer ◽  
Fluid Flow ◽  
Turbulent Flow ◽  
Particle Interactions ◽  
Two Phase ◽  
Content Type ◽  
Flow And Heat Transfer ◽  
Impingement Plate ◽  
Axis Switching ◽  
Jet Axis

Purpose The purpose of this study is to examine the physical processes experienced by a particle-laden gas due to various types of collisions, different heat transfer modalities and jet axis switching. Here, attention is focused on a particle-laden gas subjected to jet axis switching while experiencing fluid flow and heat transfer. Design/methodology/approach The methodology used to model and solve these complex problems is numerical simulation treated here as a two-phase turbulent flow in which the gas and the particles keep their separate identities. For the turbulent flow model, validation was achieved by comparisons with appropriate experimental data. The considered interactions between the fluid and the particles include one-way fluid–particle interactions, two-way fluid–particle interactions and particle–particle interactions. Findings For the fluid flow portion of the work, emphasis was placed on the particle collection efficiency and on independent variables that affect this quantity and the trajectories of the fluid and of the particles as they traverse the space between the jet orifice and the impingement plate. The extent of the effect depended on four factors: particle size, particle density, number of particles and the velocity of the fluid flow. The major effect on the heat transferred to the impingement plate occurred when direct heat transfer between the impinging particles and the plate was taken into account. Originality/value This paper deals with issues never before dealt with in the published literature: the effect of jet axis switching on the fluid mechanics of gas-particle flows without heat transfer and the effect of jet axis switching and the presence of particles on jet impingement heat transfer. The overall focus of the work is on the impact of jet axis switching on particle-laden fluid flow and heat transfer.

Effects of moving wall on the flow of micropolar fluid inside a right angle triangular cavity

2018 ◽  
Vol 28 (10) ◽  
pp. 2404-2422 ◽  
Author(s):  
Mubbashar Nazeer ◽  
N. Ali ◽  
T. Javed
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Nusselt Number ◽  
Prandtl Number ◽  
Micropolar Fluid ◽  
Richardson Number ◽  
Average Nusselt Number ◽  
Content Type ◽  
Moving Wall ◽  
Flow And Heat Transfer

Purpose The main purpose of this study is to examine the effects of moving wall on the mixed convection flow and heat transfer in a right-angle triangular cavity filled with a micropolar fluid. Design/methodology/approach It is assumed that the bottom wall is uniformly heated and the right inclined wall is cold, whereas the vertical wall is adiabatic and moving with upward/downward velocity v0/−v0, respectively. The micropolar fluid is considered to satisfy the Boussinesq approximation. The governing equations and boundary conditions are solved using the Galerkin finite element method. The Penalty method is used to eliminate the pressure term from the momentum equations. To accomplish the consistent solution, the value of the penalty parameter is taken 107. The simulations are performed for a wide range of Richardson number, micropolar parameter, Prandtl number and Reynolds number. Findings The results are presented in the form of streamlines, isotherms and variations of average Nusselt number and fluid flow rate depending on the Richardson number, Prandtl number, micropolar parameter and direction of the moving wall. The flow field and temperature distribution in the cavity are affected by these parameters. An average Nusselt number into the cavity in both cases increase with increasing Prandtl and Richardson numbers and decreases with increasing micropolar parameter, and it has a maximum value when the lid is moving in the downward direction for all the physical parameters. Research limitations/implications The present investigation is conducted for the steady, two-dimensional mixed convective flow in a right-angle triangular cavity filled with micropolar fluid. An extension of the present study with the effects of cavity inclination, square cavity, rectangular, trapezoidal and wavy cavity will be the interest of future work. Originality/value This work studies the effects of moving wall, micropolar parameter, Richardson number, Prandtl number and Reynolds number parameter in a right-angle triangular cavity filled with a micropolar fluid on the fluid flow and heat transfer. This study might be useful to flows of biological fluids in thin vessels, polymeric suspensions, liquid crystals, slurries, colloidal suspensions, exotic lubricants, solar engineering for construction of triangular solar collector, construction of thermal insulation structure and geophysical fluid mechanics, etc.

Numerical study of liquid jet impingement flow and heat transfer of a cone heat sink

2019 ◽  
Vol 29 (11) ◽  
pp. 4074-4092 ◽  
Author(s):  
Zhiguo Tang ◽  
Hai Li ◽  
Feng Zhang ◽  
Xiaoteng Min ◽  
Jianping Cheng
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Heat Sink ◽  
Numerical Study ◽  
Cone Angle ◽  
Jet Impingement ◽  
Bottom Edge ◽  
Content Type ◽  
Nusselt Numbers ◽  
Flow And Heat Transfer

Purpose The purpose of this paper is to explore the flow and heat transfer characteristics of the jet impingement onto a conical heat sink and evaluate the ability of heat transfer enhancement. Design/methodology/approach A numerical study of the flow and heat transfer of liquid impingement on cone heat sinks was conducted, and transition SST turbulence model was validated and adopted. The flow and thermal performances were investigated with the Reynolds number that ranges from 5,000 to 23,000 and cone angle that ranges from 0° to 70° in four regions. Findings Local Nusselt numbers are large, and pressure coefficients drop rapidly near the stagnation point. In the conical bottom edge, a secondary inclined jet was observed, thereby introducing a horseshoe vortex that causes drastic fluctuations in the curves of the flow and heat transfer. The average Nusselt numbers are higher in a conical protuberance than in flat plates in most cases, thus indicating that the heat transfer performance of jet impingement can be improved by a cone heat sink. The maximum increase is 13.6 per cent when the cone angle is 60°, and the Reynolds number is 23,000. Originality/value The flow and heat transfer behavior at the bottom edge of the cone heat sink is supplemented. The average heat transfer capacity of different heat transfer radii was evaluated, which provided a basis for the study of cone arrays.

Selection of CFD Turbulence Model for the Application of Submerged Multi-Air Jet Impingement

2011 ◽  
Author(s):  
Nagesh K. Chougule ◽  
Gajanan V. Parishwad ◽  
Sachin Pagnis ◽  
Prashant R. Gore ◽  
Chandrashekhar M. Sewatkar
Keyword(s):  
Heat Transfer ◽  
Turbulent Flow ◽  
Computational Cost ◽  
Jet Impingement ◽  
Turbulent Jets ◽  
Impinging Jet ◽  
Impinging Jets ◽  
Transfer Coefficients ◽  
Flow And Heat Transfer ◽  
Air Jet

Most impinging jet industrial applications involve turbulent flow in the whole domain downstream of the nozzle, and modeling turbulent flow presents the greatest challenge in the effort to rapidly and accurately predict the behavior of turbulent jets. Numerical modeling of impinging jet flows and heat transfer is employed widely for prediction, sensitivity analysis, and device design. Finite volume computational fluid dynamics (CFD) models of impinging jets have succeeded in making good predictions of heat transfer coefficients and velocity fields. The difficulties in accurately predicting velocities and transfer coefficients stem primarily from modeling of turbulence and the interaction of the turbulent flow field with the wall. In present work, the flow and heat transfer characteristics of circular multi jet array (3×3) of 5mm diameter impinging on the Flat plate heat sink are numerically analyzed based on the CFD commercial code ANSYS CFX. The relative performance of four different turbulence models, including Standard k-ε, RNG k-ε, (Renormalization Group), Standard k-ω and SST (Shear-Stress Transport) k-ω models are done for the prediction of this type of flow and heat transfer is investigated by comparing the numerical results with experimental data. It is found that SST k-ω model gives better predictions with moderate computational cost. Using SST k-ω model, the effect of Reynolds number (Re) on the average Nusselt number (Nua) of target plate is examined at Z/d = 6 (Z/d is the gap between nozzle exit and target surface).

Energy saving with using of elliptic pillows in turbulent flow of two-phase water-silver nanofluid in a spiral heat exchanger

2019 ◽  
Vol 30 (4) ◽  
pp. 2025-2049 ◽  
Author(s):  
Erfan Khodabandeh ◽  
Davood Toghraie ◽  
A. Chamkha ◽  
Ramin Mashayekhi ◽  
Omidali Akbari ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Turbulent Flow ◽  
Nanoparticle Concentration ◽  
Two Phase ◽  
Content Type ◽  
Flow And Heat Transfer ◽  
Spiral Heat Exchanger ◽  
Phase Water ◽  
Volume Method

Purpose Increasing heat transfer rate in spiral heat exchangers is possible by using conventional methods such as increasing number of fluid passes and counter flowing. In addition, newer ideas such as using pillows as baffles in the path of cold and hot fluids and using nanofluids can increase heat transfer rate. The purpose of this study is to simulate turbulent flow and heat transfer of two-phase water-silver nanofluid with 0-6 Vol.% nanoparticle concentration in a 180° path of spiral heat exchanger with elliptic pillows. Design/methodology/approach In this simulation, the finite volume method and two-phase mixture model are used. The walls are subjected to constant heat flux of q″ = 150,000 Wm−2. The inlet fluid enters curves path of spiral heat exchanger with uniform temperature Tin = 300 K. After flowing past the pillows and traversing the curved route, the working fluid exchanges heat with hot walls and then exits from the section. In this study, the effect of radiation is disregarded because of low temperature range. Also, temperature jump and velocity slipping are disregarded. The effects of thermophoresis and turbulent diffusion on nanofluid heat transfer are disregarded. By using finite volume method and two-phase mixture model, simulations are performed. Findings The results show that the flow and heat transfer characteristics are dependent on the height of pillows, nanoparticle concentration and Reynolds number. Increasing Reynolds number, nanoparticle concentration and pillow height causes an increase in Nusselt number, pressure drop and pumping power. Originality/value Turbulent flow and heat transfer of two-phase water-silver nanofluid of 0-6 per cent volume fraction in a 180° path of spiral heat exchanger with elliptic pillows is simulated.

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