scholarly journals Evaluating Velocity and Temperature Fields for Ranque-Hilsch Vortex Tube Using Numerical Simulation

2021 ◽  
pp. 100074
Author(s):  
Ahmad M. AlSaghir ◽  
Mohammad O. Hamdan ◽  
Mehmet F. Orhan
Keyword(s):  
Numerical Simulation ◽  
Vortex Tube ◽  
Temperature Fields ◽  
Velocity And Temperature Fields

Numerical Simulation of the Coordination Between Velocity and Temperature Fields for Air Flow Across Staggered Elliptic Tube Bundles

2007 ◽  
Author(s):  
Yangjun Wang ◽  
Xianhe Deng ◽  
Debin Huang
Keyword(s):  
Heat Transfer ◽  
Numerical Simulation ◽  
Heat Transfer Performance ◽  
Temperature Fields ◽  
Dimensionless Temperature ◽  
Dimensionless Velocity ◽  
Tube Bundles ◽  
Field Coordination ◽  
Velocity And Temperature Fields ◽  
Coordination Principle

The coordination between the velocity and temperature fields in 2-D developed turbulent flow is analyzed for air across the staggered elliptic tube bundles by means of numerical simulation. The results indicate that the convective heat transfer performance is dominated by the degree of coordination between the velocity and temperature fields. Furthermore, the included angle β between the dimensionless velocity and dimensionless temperature gradient vectors is one of the important factors to control the coordination. The field coordination can be improved by adjusting the include angle β, subsequently the heat transfer can be enhanced effectively. Field coordination principle promotes the development of heat transfer research in a controllable direction.

Numerical Simulation and Flame Characteristics Analysis of Non-Premixed Swirling Combustion

2021 ◽  
Author(s):  
Yi Su ◽  
Bin Zhang ◽  
Junqing Hou ◽  
Yifeng Chen ◽  
Jieyu Jiang ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
High Temperature ◽  
High Velocity ◽  
Temperature Fields ◽  
Pollutant Emission ◽  
Form Complex ◽  
High Temperature Area ◽  
Swirling Flames ◽  
Velocity And Temperature Fields ◽  
Temperature Area

Abstract Swirling flames are important in practical industrial combustors. The dynamic characteristics of swirling flames form complex velocity and temperature fields, which indicate combustion efficiency and influence pollutant emission. A reliable numerical simulation that can calculate the entire velocity and temperature fields is required to understand and investigate the underlying combustion mechanism. The governing equations of the methane swirling combustion process consist of the mass conservation, Navier-Stokes, and energy equations, all of which are solved by the SIMPLE algorithm based on finite volume method. This study performed a simulation using the realizable k-ε and non-premixed models in conjunction with the GRI Mech 3.0 mechanism. The characteristics of swirling combustion were analyzed on the bases of visualizations of temperature distribution, velocity distribution, and streamlines. In each cross section with varying heights from the nozzle, the high velocity and high temperature areas showed similar closed or semi-closed annular structures. In the central longitudinal section, the V-shaped high temperature and high velocity regions showed the swirling structure of the combustion flow field. The high temperature area did not coincide with the high velocity area but was located relatively downstream. The high velocity area was in the periphery of the high temperature area. Furthermore, the effects of swirl blade position on methane combustion characteristics were discussed. The validity of the numerical simulation results was verified by the simultaneous laser measurement of 3D temperature and velocity fields in the swirling flame.

Process Optimization of Large Turbine Blade Casting Base on Numerical Simulation

2009 ◽  
Vol 16-19 ◽  
pp. 535-539
Author(s):  
Deng Yu Gai ◽  
Yu Zhao Chu ◽  
Qing Fen Li ◽  
Qun Xia Li
Keyword(s):  
Numerical Simulation ◽  
Velocity Field ◽  
Stress Field ◽  
Turbine Blade ◽  
Process Optimization ◽  
Temperature Fields ◽  
Solidification Processes ◽  
Velocity And Temperature Fields ◽  
Blade Casting ◽  
Filling And Solidification

3-D velocity and temperature fields of mold filling and solidification processes of large turbine blade casting were simulated. It indicated that the velocity field of upright casting is faster and steadier than lying casting. The deformation was predicted and the rule of deformation was reflected by analyzing stress field during solidification of upright casting. The casting processes were optimized, and then applied to produce castings.

Numerical Simulation of Temperature Field on Different Surface Structure of Bicycle Brake Pairs

2014 ◽  
Vol 697 ◽  
pp. 235-238
Author(s):  
Gang Wu ◽  
Can Chao Huang ◽  
Hong Ling Qin ◽  
Chun Hua Zhao
Keyword(s):  
Heat Transfer ◽  
Numerical Simulation ◽  
Surface Structure ◽  
Surface Structures ◽  
Temperature Fields ◽  
Transfer Model ◽  
Pair Model ◽  
Layer Composite ◽  
Positive Effect ◽  
Heat Loads

Using the basic principle of heat transfer, tribology and numerical simulation, a two-dimensional heat transfer model of the three-layer composite brake pair materials were established. The temperature fields of brake pairs during the process of friction were analyzed. Applied given heat loads at different time node on the brake pair model, the temperatures of different bicycle brake pairs were compared and analyzed. Results show that the improved surface structures of brake pair have positive effect on decreasing the temperature of contact areas than that of ordinary surface structure.

New benchmark solutions for transient natural convection in partially porous annuli

2016 ◽  
Vol 26 (3/4) ◽  
pp. 1187-1225 ◽  
Author(s):  
Nicola Massarotti ◽  
Michela Ciccolella ◽  
Gino Cortellessa ◽  
Alessandro Mauro
Keyword(s):  
Natural Convection ◽  
Free Convection ◽  
Transient Flow ◽  
Flow Behavior ◽  
Outer Radius ◽  
Temperature Fields ◽  
Content Type ◽  
Transient Natural Convection ◽  
Velocity And Temperature Fields ◽  
Benchmark Solutions

Purpose – The purpose of this paper is to focus on the numerical analysis of transient free convection heat transfer in partially porous cylindrical domains. The authors analyze the dependence of velocity and temperature fields on the geometry, by analyzing transient flow behavior for different values of cavity aspect ratio and radii ratio; both inner and outer radius are assumed variable in order to not change the difference ro-ri. Moreover, several Darcy numbers have been considered. Design/methodology/approach – A dual time-stepping procedure based on the transient artificial compressibility version of the characteristic-based split algorithm has been adopted in order to solve the transient equations of the generalized model for heat and fluid flow through porous media. The present model has been validated against experimental data available in the scientific literature for two different problems, steady-state free convection in a porous annulus and transient natural convection in a porous cylinder, showing an excellent agreement. Findings – For vertically divided half porous cavities, with Rayleigh numbers equal to 3.4×106 for the 4:1 cavity and 3.4×105 for the 8:1 cavity, the numerical results show that transient oscillations tend to disappear in presence of cylindrical geometry, differently from what happens for rectangular one. The magnitude of this phenomenon increases with radii ratio; the porous layer also affects the stability of velocity and temperature fields, as oscillations tend to decrease in presence of a porous matrix with lower value of the Darcy number. Research limitations/implications – A proper analysis of partially porous annular cavities is fundamental for the correct estimation of Nusselt numbers, as the formulas provided for rectangular domains are not able to describe these problems. Practical implications – The proposed model represents a useful tool for the study of transient natural convection problems in porous and partially porous cylindrical and annular cavities, typical of many engineering applications. Moreover, a fully explicit scheme reduces the computational costs and ensures flexibility. Originality/value – This is the first time that a fully explicit finite element scheme is employed for the solution of transient natural convection in partially porous tall annular cavities.

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.

Thermally Induced Flow in a Rotating Annulus Filled With a Compressible Fluid

1988 ◽  
Vol 110 (2) ◽  
pp. 134-139 ◽  
Author(s):  
M. A. Ortega ◽  
J. T. Sielawa
Keyword(s):  
Flow Field ◽  
Inner Core ◽  
Temperature Fields ◽  
Bottom Plate ◽  
Rossby Number ◽  
Thermally Induced ◽  
Coaxial Cylinders ◽  
Induced Flow ◽  
Velocity And Temperature Fields ◽  
Induced Velocity

The thermally induced flow field, in a rapidly rotating container consisting of a pair of coaxial cylinders bounded on the top and bottom by horizontal end plates, is considered. The top plate is heated and the bottom plate is cooled, both by small amounts, so that the thermal Rossby number is small, and the cylinders are supposed to be conductive. The induced velocity and temperature fields are determined by subdivision of the flow field; the equation for the central part, the inner core, is solved numerically as well as analytically.

Multigrid Numerical Solutions of Non-Isothermal Laminar Recirculating Flows

1999 ◽  
Author(s):  
Marcelo J. S. de Lemos ◽  
Maximilian S. Mesquita
Keyword(s):  
Numerical Solutions ◽  
Rectangular Domain ◽  
Optimal Number ◽  
Computational Effort ◽  
Temperature Fields ◽  
Two Dimensional ◽  
Discretization Scheme ◽  
Multigrid Algorithm ◽  
Finite Volume Discretization ◽  
Velocity And Temperature Fields

Abstract The present work investigates the efficiency of the multigrid numerical method applied to solve two-dimensional laminar velocity and temperature fields inside a rectangular domain. Numerical analysis is based on the finite volume discretization scheme applied to structured orthogonal regular meshes. Performance of the correction storage (CS) multigrid algorithm is compared for different inlet Reynolds number (Rein) and number of grids. Up to four grids were used for both V- and W-cycles. Simultaneous and uncoupled temperature-velocity solution schemes were also applied. Advantages in using more than one grid is discussed. Results further indicate an increase in the computational effort for higher Rein and an optimal number of relaxation sweeps for both V- and W-cycles.

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