scholarly journals Flow analysis in seamless hot-extruded pipes with helical inner ribbing surface

2021 ◽  
Vol 2088 (1) ◽  
pp. 012011
Author(s):  
Ya Ig Kosmatskiy ◽  
M Yu Egorov ◽  
V D Lychakov
Keyword(s):  
Heat Transfer ◽  
Numerical Simulation ◽  
Critical Reynolds Number ◽  
Transient Flow ◽  
Flow Analysis ◽  
Hot Extrusion ◽  
Turbulent Regime ◽  
Transfer Processes ◽  
Different Types ◽  
Internal Fins

Abstract The article is devoted to numerical simulation of heat transfer processes occurring during the flow of a coolant in seamless hot-extrusion pipes with a spiral inner fin surface (TMK-IRS). A description of the numerical modeling technique is given along with the interface of the program used to create different types of internal fins. Thermohydraulic analysis of finned pipes for transient, turbulent and laminar flow regimes has been carried out. An estimate of the critical Reynolds number characterizing the transition to a turbulent regime, the nature of the transient flow regime in comparison with other classical cases is given.

Direct numerical simulation of a turbulent jet impinging on a heated wall

2015 ◽  
Vol 764 ◽  
pp. 362-394 ◽  
Author(s):  
T. Dairay ◽  
V. Fortuné ◽  
E. Lamballais ◽  
L.-E. Brizzi
Keyword(s):  
Heat Transfer ◽  
Numerical Simulation ◽  
Nusselt Number ◽  
Direct Numerical Simulation ◽  
Temperature Fields ◽  
Heated Wall ◽  
Small Scale ◽  
Turbulent Regime ◽  
High Heat Transfer ◽  
Radial Evolution

AbstractDirect numerical simulation (DNS) of an impinging jet flow with a nozzle-to-plate distance of two jet diameters and a Reynolds number of 10 000 is carried out at high spatial resolution using high-order numerical methods. The flow configuration is designed to enable the development of a fully turbulent regime with the appearance of a well-marked secondary maximum in the radial distribution of the mean heat transfer. The velocity and temperature statistics are validated with documented experiments. The DNS database is then analysed focusing on the role of unsteady processes to explain the spatial distribution of the heat transfer coefficient at the wall. A phenomenological scenario is proposed on the basis of instantaneous flow visualisations in order to explain the non-monotonic radial evolution of the Nusselt number in the stagnation region. This scenario is then assessed by analysing the wall temperature and the wall shear stress distributions and also through the use of conditional averaging of velocity and temperature fields. On one hand, the heat transfer is primarily driven by the large-scale toroidal primary and secondary vortices emitted periodically. On the other hand, these vortices are subjected to azimuthal distortions associated with the production of radially elongated structures at small scale. These distortions are responsible for the appearance of very high heat transfer zones organised as cold fluid spots on the heated wall. These cold spots are shaped by the radial structures through a filament propagation of the heat transfer. The analysis of probability density functions shows that these strong events are highly intermittent in time and space while contributing essentially to the secondary peak observed in the radial evolution of the Nusselt number.

scholarly journals NUMERICAL SIMULATION OF HEAT TRANSFER PROCESSES IN COMPOSITES WITH MULTI-SIZE INCLUSIONS

2019 ◽  
Vol 4 ◽  
pp. 114-120
Author(s):  
I. Zaginaylo ◽  
◽  
A. Pysarenko ◽  
D. Spiridonov ◽  
D. Levitskiy ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Numerical Simulation ◽  
Transfer Processes

Numerical Study of Heat Transfer in Turbulent Cross-Flow Over Porous-Coated Cylinder

2017 ◽  
Author(s):  
N. Rahmati ◽  
Z. Mansoori ◽  
M. Saffar-Avval ◽  
G. Ahmadi
Keyword(s):  
Heat Transfer ◽  
Porous Media ◽  
Nusselt Number ◽  
Turbulent Flows ◽  
Metal Foam ◽  
Numerical Study ◽  
Flow Analysis ◽  
Cross Flow ◽  
Local Thermal Equilibrium ◽  
Turbulent Regime

In the present paper, a numerical study has been conducted to investigate the heat transfer from a constant temperature cylinder covered with metal foam. The cylinder is placed horizontally and is subjected to a constant mean cross-flow in turbulent regime. The Reynolds Averaged Navier-Stokes (RANS) and Darcy-Brinkman-Forchheimer equations are combined and used for flow analysis. The energy equation used assumes local thermal equilibrium between fluid and solid phases in porous media. The k-ω SST turbulence model is used to evaluate the eddy viscosity that is implemented in the momentum and energy equations. The flow in the metal foam (porous media) is in laminar regime. Governing equations are solved using the finite volume SIMPLEC algorithm. The effect of thermophysical properties of metal foam such as porosity and permeability on the Nusselt number is investigated. The results showed that using a metal porous layer with low porosity and high Darcy number in high Reynolds number turbulent flows markedly increases heat transfer rates. The corresponding increase in the Nusselt number is as high as 10 times that of a bare tube without the metal foam.

scholarly journals NUMERICAL SIMULATION OF HEAT TRANSFER PROCESSES IN LINING AND OPTIMIZATION OF HEAT WORK OF THE UNIT

2018 ◽  
Vol 15 (30) ◽  
pp. 609-626
Author(s):  
B. A. UNASPEKOV ◽  
R. BAZAROV ◽  
S. S. AUELBEKOV ◽  
T. I. IRGIBAEV ◽  
O. D. SEITKAZINOV ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Numerical Simulation ◽  
High Temperature ◽  
Natural Gas ◽  
Tunnel Kiln ◽  
Computer Calculation ◽  
Combined System ◽  
Transfer Processes ◽  
Hot Air ◽  
Burning Zone

The features of heat and mass transfer inlining of high-temperature tunnel kiln for the burning of refractory materials are revealed by numerical simulation of heat transfer processes. Use of modern computer calculation programs permits to choose optimal constructions of trolley walls and heart lining. This ensures improved hermeticity of workspace and 15-20% reduction of heat loss. We studied the operation of a hightemperature of the unit with a combined system that ensured efficient burning of natural gas as well as regulation of temperature regime in the thermal aggregate workspace. A procedure was advanced to calculate consumption of fuel by gas burners and hot air over burning zone positions of high-temperature tunnel kilns when using a combined system of natural gas burning. The heat work of a tunnel kiln was optimized. This permitted to supply maximal quantity of hot air and natural gas into the initial positions of burning zone of tunnel kiln and to ensure technologically required temperatures of products burning (1780-1800ºС).

scholarly journals Numerical Simulation of Fluid Flow and Heat Transfer Processes 2014

2014 ◽  
Vol 7 (2) ◽  
pp. 645351 ◽  
Author(s):  
Bo Yu ◽  
Shuyu Sun ◽  
Jinjia Wei ◽  
Dongliang Sun ◽  
Yi Wang ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Numerical Simulation ◽  
Fluid Flow ◽  
Transfer Processes ◽  
Flow And Heat Transfer
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