Simulation of Laminar Slot Jets Impinging on a Moving Surface

2002 ◽  
Vol 124 (6) ◽  
pp. 1049-1055 ◽  
Author(s):  
Himadri Chattopadhyay ◽  
Sujoy K. Saha
Keyword(s):  
Heat Transfer ◽  
Nozzle Exit ◽  
Momentum Flux ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Surface Velocity ◽  
Exit Angle ◽  
Total Heat Transfer ◽  
Moving Surface ◽  
Flow And Heat Transfer

Laminar flow and heat transfer on a moving surface due to a bank of impinging slot jets have been numerically investigated. Two types of jet, namely axial and knife-jet with an exit angle of 60 deg were considered. The surface velocity up to two times the jet velocity at the nozzle exit was imposed on the impinging surface. It has been observed that while with increasing velocity of the impinging surface, the total heat transfer reduces; the distribution pattern becomes more uniform. For the same amount of mass and momentum flux at the nozzle exit, heat transfer from the axial jet is considerably higher than that from the vectored jets at all surface velocities considered. It was found that the local heat transfer over the surface for the case of the axial jet and the knife-jet scales with Re0.5 and Re0.55, respectively.

Numerical Study of Flow and Heat Transfer for Circular Jet Impingement on the Bottom of a Cylindrical Cavity

1993 ◽  
Vol 115 (3) ◽  
pp. 292-297 ◽  
Author(s):  
S. Gavali ◽  
K. Karki ◽  
S. Patankar ◽  
K. Miura
Keyword(s):  
Heat Transfer ◽  
Nozzle Exit ◽  
Numerical Study ◽  
Jet Impingement ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Separation Distance ◽  
Laminar Jet ◽  
Flow And Heat Transfer ◽  
Impingement Surface

A numerical study is presented for an axisymmetric laminar jet impingement on a confined disk, with the spent fluid being collected through an annual channel that is concentric with the nozzle. In this study, parametric variations were made of the dimensionless separation distance between the nozzle exit and the impingement surface, of the ratio of the diameter of the impingement surface to the nozzle diameter, and of the Reynolds number. The flow field is characterized by two recirculation zones, one adjacent to the nozzle exit and the other near the confining wall. The local heat transfer distribution on the impingement surface exhibits an off-axis maximum and a local minimum near the confining wall. The nozzle separation distance has an effect on surface heat transfer only for configurations with closet confinement. The thermal boundary condition on the impingement surface is found to have little effect on the total heat transfer.

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.

Numerical Prediction of Flow and Heat Transfer Past a Circular Tube With Annular Fins

2003 ◽  
Author(s):  
D. Chakraborty ◽  
G. Biswas ◽  
P. K. Panigrahi
Keyword(s):  
Heat Transfer ◽  
Circular Tube ◽  
Flow Characteristics ◽  
Cross Flow ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Stagnation Line ◽  
Flow And Heat Transfer ◽  
Annular Fin ◽  
Annular Fins

A numerical investigation was carried out to study the flow and heat transfer behavior of a vertical circular tube, which is situated between two annular fins in cross-flow. The flow structure of the limiting streamlines on the surface of the circular tube and the annular fins was analysed. A finite volume method was employed to solve the Navier-Stokes and energy equations. The numerical results pertaining to heat transfer and flow characteristics were compared with the available experimental results. The following salient features were observed in this configuration. A horseshoe vortex system was formed at the junction of the stagnation line of the circular tube and the annular fin. The separation took place at the rear of the tube. The influence of the horseshoe vortices on local heat transfer was substantial. The ratio of the axial gap between two annular fins (L) to the radial protrusion length of the annular fin (LR) was identified as an important parameter. The flow and heat transfer results were presented for different L/LR ratios for a Reynolds number of 1000.

Flow and Heat Transfer Past a Sudden Contraction With a Porous Insert Using Linear and Non-Linear Turbulence Models

2004 ◽  
Author(s):  
Marcelo Assato ◽  
Marcelo J. S. de Lemos
Keyword(s):  
Heat Transfer ◽  
Turbulence Models ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Porous Insert ◽  
Macroscopic Models ◽  
Flow And Heat Transfer ◽  
Non Linear ◽  
Abrupt Contraction ◽  
Stream Lines

This work presents a numerical investigation for the turbulent flow and heat transfer in an abrupt contraction channel with a porous material placed in a flow passage. The channel has a contraction rate of 3:2. Results for the hybrid medium were obtained using linear and non-linear k-ε macroscopic models. It was used an inlet Reynolds number of Re = 132000 based on the height of the step. Parameters such as porosity, permeability and thickness of the porous insert were varied in order to analyze their effects on the flow pattern. The results of local heat transfer, friction coefficient and stream lines obtained by the two turbulence models were compared for the cases without and with porous insertion of thickness a/H=0.083, 0.166 and 0.250, where H is the step height. Insert porosity of varied between 0.85 and 0.95 with permeability in the range 10−6–10−2 m2.

Simulation of Flow and Heat Transfer in the MTPV Systems

2013 ◽  
Vol 448-453 ◽  
pp. 3291-3295
Author(s):  
Ge Ping Wu ◽  
Jun Wang ◽  
Ping Lu
Keyword(s):  
Heat Transfer ◽  
Thermal Resistance ◽  
Friction Factor ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Heat Transfer Characteristics ◽  
Pressure Losses ◽  
Transfer Characteristics ◽  
Flow And Heat Transfer ◽  
Different Types

Flow and heat transfer characteristics in the microchannel cooling passages with three different types of the MTPV systems are numerically investigated. Reynolds ranged from 100 to 1000 and hydraulic diameter from 0.4mm to 0.8mm. The steady, laminar flow and heat transfer equations are solved in a finite-volume method. The local heat transfer characteristics, thermal resistance, Nusselt numbers, friction factor and pressure losses of the different types are analyzed. A comparison of the heat transfer coefficient, pressure losses and friction factor of the different microchannels are also presented. The heat transfer performance of the rob bundles microchannel is found to be much better than others. However, the rectangular passage has the lowest thermal resistance than the other types of microchannels.

The Effect of Entrance Configuration on Local Heat-transfer Coefficients in Subsonic Diffusers

1972 ◽  
Vol 94 (4) ◽  
pp. 355-359 ◽  
Author(s):  
E. O. Stoffel ◽  
J. R. Welty
Keyword(s):  
Heat Transfer ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Two Dimensional ◽  
Transfer Coefficients ◽  
Transfer Rates ◽  
Heat Transfer Coefficients ◽  
Flow And Heat Transfer ◽  
Transfer Equations ◽  
Subsonic Diffuser

The effects of square and reentrant entrances on flow regimes (no “appreciable” separation, large transitory stall, and fully developed two-dimensional stall) and local heat-transfer coefficients were determined with air flowing through a symmetrical, plane-wall, two-dimensional subsonic diffuser with one of the diverging walls heated and maintained isothermal. Flow and heat-transfer studies were made for the following ranges: 2θ = 0 to 45 deg, L/W = 6 to 18, and Rextut = 4 × 104 to 3 × 105. Results indicated that 2θ, L/W, and entrance configuration greatly affected the flow regime and heat transfer. Equations relating Um′ to Ut, Ur to Ut, and equations of the type Nu = C Pr0.6Rex0.8 are presented. For the configurations tested, heat-transfer rates were greater for reentrant than for square entrances.

Numerical Investigation on Conjugate Heat Transfer of Supercritical CO2 in Rolling Motion

2018 ◽  
Author(s):  
Zhenxing Zhao ◽  
Mengran Liao ◽  
Yong Liu ◽  
Qi Xiao ◽  
Xingsheng Lao ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Supercritical Co2 ◽  
Local Heat Transfer ◽  
Periodic Oscillation ◽  
Local Heat ◽  
Rolling Motion ◽  
Flow And Heat Transfer ◽  
Ocean Environment ◽  
The Stability ◽  
Phase Fluid

The numerical calculations with and without rolling motions were conducted to investigate the effects of ocean environment on flow and heat transfer of supercritical CO2. The AKN k-epsilon model was selected to model the turbulent flow and heat transfer of supercritical fluid. It concludes that the effect of rolling motion on the supercritical CO2 in LPV region is much greater than that on conventional single-phase fluid. The rolling motion can cause the periodic oscillation of the local heat transfer and suppress the nonuniform heat transfer. The secondary flow is induced by both the rolling motion and buoyancy force. The heat transfer is enhanced gradually as the rolling period decreasing or rolling amplitude increasing, but the corresponding pressure drop varies more violently to affect the stability and controllability of the heat exchanger.

Numerical Analysis of Fluid Flow and Heat Transfer in Entrance and Fully Developed Regions of a Channel With Porous Baffles

2016 ◽  
Vol 138 (6) ◽  
Author(s):  
Amin Davari ◽  
Mehdi Maerefat
Keyword(s):  
Heat Transfer ◽  
Fluid Flow ◽  
Simple Algorithm ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Darcy Number ◽  
Performance Ratio ◽  
Local Thermal Equilibrium ◽  
Thermal Conductivity Ratio ◽  
Flow And Heat Transfer

In the present study, analysis of fluid flow and heat transfer in the entrance and periodically fully developed regions of a channel with porous baffles is numerically studied. The Navier–Stokes and Brinkman–Forchheimer equations are used to model the fluid flow in the open and porous regions. The flow is assumed to be laminar. A finite-volume based method in conjunction with the SIMPLE algorithm is used to solve the equations. The local thermal equilibrium model is adopted in the energy equation to evaluate the solid and fluid temperatures. The effects of parameters such as baffle height, baffle spacing, Reynolds number, and thermal conductivity ratio between the porous baffles and the fluid on the flow field and local heat transfer rate are studied at relatively low and high values of Darcy number. Results show that local heat transfer coefficient significantly depends on the formation and variation of the recirculation caused by the porous baffles, such that, in the cases where use of porous baffles leads to recirculation zone, the local Nusselt number in the entrance region would be less than that of the fully developed region. It is also shown that heat transfer performance ratio is significantly improved for high Prandtl number fluids.

Numerical Simulations of Flow Fields and Heat Transfer Characteristics in Tenon Joint Gap Between Turbine Blade and Disk Under Rotating Conditions

2017 ◽  
Author(s):  
Da-wei Chen ◽  
Hui-ren Zhu ◽  
Yang Xu ◽  
Xiao-meng Jia ◽  
Cong Liu ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Turbine Blades ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Local Heat Transfer Coefficient ◽  
Flow And Heat Transfer ◽  
Joint Gap ◽  
The Right

Turbine blades and the disks are connected by tenons. There is a pair of jagged assembly clearance between each tenon and corresponding mortise. In practical engineering applications, flow and heat transfer characteristics in assembly clearance used to be simplified. In order to obtain more accurate temperature fields of the turbine blades and disks, detailed study of the flow and heat transfer mechanism in tenon joint gap is necessary. In this paper, two typical assembly clearances under the stationary and rotating conditions were investigated numerically, including double S-shaped and double Crescent-shaped. The inlet Reynolds numbers range from 5,500 to 50,000 and the Rotation numbers range from 0 to 0.005. The results show that the fluids in the two branches of the double S-shaped channel have different flow characteristics under rotating conditions. A vortex is formed at the corner of the left branch and the vortex scale can be influenced by Re and Ro. The large vortex decreases the local heat transfer coefficient. In the right branch, the three-dimensional flow from the flat wall to the concave wall increases the local heat transfer coefficient of different regions. For the double Crescent-shaped channel, the region with higher velocity is offset to the right of the channel which leads to higher local heat transfer coefficient under rotating conditions. The simulation results have great significance to the heat transfer analysis of turbine blades and disks.

scholarly journals Numerical Investigation of Flow and Heat Transfer in a Rotor-Stator Cavity with Centripetal Carbon Dioxide Through-Flow

Energies ◽  
2019 ◽  
Vol 12 (13) ◽  
pp. 2613
Author(s):  
Hu ◽  
Li ◽  
Fu ◽  
Gu ◽  
Ren ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Carbon Dioxide ◽  
Flow Parameter ◽  
Local Heat Transfer ◽  
Local Heat ◽  
The Core ◽  
Moment Coefficient ◽  
Flow And Heat Transfer ◽  
Through Flow ◽  
The Moment

A centrifugal carbon dioxide compressor is a kind of general machine with extensive applications. The geometry of the side chambers of the compressors can be determined by studying the rotor-stator cavity with centripetal through-flow. In this paper, numerical simulations were conducted to predict the characteristics of flow and heat transfer. Three different speeds of rotation and two axial gap widths were considered. The correlations of the core swirl ratios were determined by fitting the results for two axial gap widths. The amounts of the moment coefficients of the disk were predicted. In order to better analyze the temperature field, the radial distributions of the local heat transfer coefficient were numerically investigated. According to the simulation results, the average Nusselt number was found to be dominated by the turbulent flow parameter. It also seemed to be proportional to the moment coefficient at a fixed circumferential Reynolds number.

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