Application of an Integral Turbulence Model to Close the Model of an Anisotropic Porous Body as Applied to Rod Structures

Vlasov, M. N.; Merinov, I. G.

doi:10.3390/fluids7020077

Cited by 5 publications

(3 citation statements)

References 25 publications

(37 reference statements)

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“…Paper [4] presented the results of a numerical simulation of coolant flow through bundles of cylindrical rods with both longitudinal and transverse flow. Such rod assemblies are typical for nuclear power plant equipment.…”

Section: Heat Exchanger With Sbrcmentioning

confidence: 99%

CFD Modeling of Heat Exchanger with Small Bent Radius Coils Using Porous Media Model

Dmitriev

Kurkin

Dobrov

et al. 2023

Fluids

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The efficiency of heat transfer in air-cooled heat exchangers of various industrial facilities depends on the flow rate of the coolant, its inlet temperature and ambient temperature. These parameters are transient and depend both on the features of the technological process and on weather conditions. One option for a compact design of heat exchangers is the use of close-packed coils with a small bending radius. In this case, heat transfer in the complex geometry of the annular space cannot be described by simple one-dimensional dependencies. To solve this problem, it is necessary to consider the three-dimensional spatial structure of the heat exchange surface. Since the size of the grid elements will be several orders of magnitude less than the size of the facility, the size of the computational grids for CFD modeling full-scale heat exchangers will be billions of finite volumes, and even on powerful supercomputers, the solution time will be about a month. One way to reduce computational costs is to use reduced order models, in which the computational domain is not modeled directly; instead, simplified models, such as a porous medium model, are used to describe it. However, such models require additional closing relations and coefficients that characterize the actual channel geometry. This paper presents a technique for creating a digital twin of a heat exchanger with small bend radius coils based on a porous medium model. The values of heat transfer coefficients and hydraulic resistance depend on the speed of air movement in the space between the coils. The calculated value of the thermal power obtained using the strengthened model was 529 kW, which corresponds to the passport data of 500 kW, with less than 6% deviation for the heat exchanger under study. This confirms the correctness of the calculation with accepted simplifications. The calculation time in this case was only a few minutes when using a personal computer. The developed numerical model allows for the resolution of performance characteristics based on the temperature of the cooled medium at the inlet, air temperature, and fan speed. Analyzing the different modes of turning on the cooling fans made it possible to determine the values of the thermal power when turning off the fans or reducing the number of revolutions.

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Section: Heat Exchanger With Sbrcmentioning

confidence: 99%

CFD Modeling of Heat Exchanger with Small Bent Radius Coils Using Porous Media Model

Dmitriev

Kurkin

Dobrov

et al. 2023

Fluids

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“…The methods of computational fluid dynamics make it possible to obtain the solution of hydrodynamic equations in numerical form, taking into account complex boundary conditions. Thus, in [26][27][28][29][30][31] the results of numerical studies and the values of heat transfer coefficients for various tubular heat exchangers, in evaporators, coolers, and other surfaces are presented. In papers [32][33][34][35][36], different models of turbulence are considered depending on the viscosity and flow parameters, as well as the roughness of the domain walls.…”

Section: Introductionmentioning

confidence: 99%

Numerical Simulation of Heat Transfer and Spread of Virus Particles in the Car Interior

2023

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The epidemic caused by the coronavirus infection SARS-CoV-2 at the beginning of 2022 affected approximately 500 million people in all countries. The source of infection is the particles of the virus, which, when breathing, talking, and coughing, are released with the respiratory droplets and aerosol dust of an infected person. Actions aimed at combating and minimizing the consequences of coronavirus infection led to taking measures in scientific areas to investigate the processes of the spread of viral particles in the air, in ventilation, and air conditioning systems of premises and transport, filtration through masks, the effect of partitions, face shields, etc. The article presents a mathematical model of the spread of viral particles in technological transport. Air intake diverters and the operator’s respiratory tract are the sources of the virus. The Euler–Lagrange approach was used to simulate liquid droplets in a flow. Here, the liquid phase is considered as a continuous medium using Navier–Stokes equations, the continuity equation, the energy equation, and the diffusion equation. Accounting for diffusion makes it possible to explicitly model air humidity and is necessary to consider the evaporation of droplets (changes in the mass and size of particles containing the virus). Liquid droplets are modeled using the discrete-phase model (DPM), in which each particle is tracked in a Lagrange coordinate system. The DPM method is effective, since the volume fraction of particles is small relative to the total volume of the medium, and the interaction of particles with each other can be neglected. In this case, the discrete and continuous phases are interconnected through the source terms in the equations. The averaged RANS equations are solved numerically using the k-ω turbulence model in the Ansys Fluent package. The task was solved in a static form and in the time domain. For a non-stationary problem, the stabilization time of the variables is found. The simulation results are obtained in the form of fields of pressures, velocities, temperatures and air densities, and the field of propagation of particles containing the virus. Various regimes were studied at various free flow rates and initial velocities of droplets with viral particles. The results of trajectories and velocities of particles, and particle concentrations depending on time, size, and on the evaporability of particles are obtained.

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“…In [35][36][37][38][39][40][41][42], the results of CFD analysis of thermal and hydrodynamic characteristics for various vehicles were presented, and optimization issues for various configurations and cab geometries were considered. Using numerical analysis based on CFD [43][44][45] makes it possible to obtain excellent results in modeling air flows, especially considering turbulence [46,47].…”

Section: Introductionmentioning

confidence: 99%

Modeling of Flow Heat Transfer Processes and Aerodynamics in the Cabins of Vehicles

Beskopylny

Panfilov

Meskhi

2022

Fluids

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Ensuring comfortable climatic conditions for operators in the cabin of technological machines is an important scientific and technical task affecting operator health. This article implements numerical and analytical modeling of the thermal state of the vehicle cabin, considering external airflow and internal ventilation. A method for calculating the heat transfer coefficients of a multilayer cabin wall for internal and external air under conditions of forced convective heat exchange is proposed. The cabin is located in the external aerodynamic flow to consider the speed and direction of the wind, as well as the speed of traffic. Inside the cabin, the operation of the climate system is modeled as an incoming flow of a given temperature and flow rate. The fields of velocities, pressures, and temperatures are calculated by the method of computer hydrodynamics for the averaged Navier–Stokes equations and the energy equation using the turbulence model. To verify the model, the values of the obtained heat transfer coefficients were compared with three applied theories obtained from experimental data based on dimensionless complexes for averaged velocities and calculated by a numerical method. It is shown that the use of numerical simulation considering the external air domain makes it possible to obtain more accurate results from 5% to 75% compared to applied theories, particularly in areas with large velocity gradients. This method makes it possible to get more accurate values of the heat transfer coefficients than for averaged velocities.

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Application of an Integral Turbulence Model to Close the Model of an Anisotropic Porous Body as Applied to Rod Structures

Cited by 5 publications

References 25 publications

CFD Modeling of Heat Exchanger with Small Bent Radius Coils Using Porous Media Model

CFD Modeling of Heat Exchanger with Small Bent Radius Coils Using Porous Media Model

Numerical Simulation of Heat Transfer and Spread of Virus Particles in the Car Interior

Modeling of Flow Heat Transfer Processes and Aerodynamics in the Cabins of Vehicles

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