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Thermal hydraulic simulation of reactor of HTR-PM based on thermal-fluid network and simple algorithm

PROGRESS IN NUCLEAR ENERGY 2013年 62卷 83-93页

作者： Zhou, Yangping Zhou, Kefeng Ma, Yuanle Sui, Zhe Tsinghua Univ Inst Nucl & New Energy Technol Beijing 100084 Peoples R China Nucl & Radiat Safety Ctr Beijing 100082 Peoples R China

This paper provides the model development and its verifications for the reactor thermal-hydraulic transient model for the High Temperature Gas-cooled Reactor Pebble-bed Module (HTR-PM). A thermal-fluid network is constructed to simulate the complexity of the flow and heat transfer structure in the reactor of HTR-PM. simple algorithm is applied to solve the conservation equations of the thermal-fluid network to simulate the transient behavior of the high speed turbulent helium flow. A calculation process is proposed for coupling the high speed helium flow and the complex heat transfer structure. A FORTRAN code was developed based on the solution method and the thermal-fluid network. Several test cases including two steady states and a Control Rod Withdrawal accident are simulated by this code and the results are compared to those obtained by a safety analysis code, namely THERMIX. The good agreement between the two codes indicates that the proposed model and solution method based on simple algorithm is reasonable and applicable for simulating the thermal-hydraulic behavior in reactor of HTR-PM. (C) 2012 Elsevier Ltd. All rights reserved.

关键词： Thermal-hydraulic simulation Thermal-fluid network simple algorithm HTR-PM

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APPLICATION OF A NEW SINGLE STAGGERED GRID METHOD TO THE HEAT TRANSFER PROBLEMS

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THERMAL SCIENCE 2019年第Sup3期23卷 S631-S637页

作者： Liang, Xin Liu, Guan-Nan China Univ Min & Technol Key Lab Coal Based Capture & Geol Storage Jiangsu Xuzhou Jiangsu Peoples R China China Univ Min & Technol State Key Lab GeoMech & Deep Underground Engn Xuzhou Jiangsu Peoples R China China Univ Min & Technol Sch Mech & Civil Engn Xuzhou Jiangsu Peoples R China

In this paper, a new single staggered grid method is proposed to solve the fluid dynamic problems numerically. The advantages of the new grid method are analyzed in comparison with the classical grid algorithms such as the staggered grids, collocated grids and semi-staggered grids. The discretization of the basic equations for the fluid dynamics on the new single staggered grids is derived and the corresponding simple algorithm is introduced. As an example, the heat transfer problem offluid-flow at a right angle is solved to prove the validity of the new single staggered grid method.

关键词： single staggered grid method simple algorithm fluid dynamics heat transfer problem

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Transient characteristics of a parabolic trough direct-steam generation process

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RENEWABLE ENERGY 2019年第May期135卷 800-810页

作者： Li, Lu Sun, Jie Li, Yinshi He, Ya-Ling Xu, Haojie Xi An Jiao Tong Univ Key Lab Thermofluid Sci & Engn MOE Sch Energy & Power Engn Xian 710049 Shaanxi Peoples R China Xi An Jiao Tong Univ Sch Chem Engn & Technol Xian 710049 Shaanxi Peoples R China

Solar-powered direct steam generation (DSG) is attractive for power generation and industrial utilization due to the combination of renewable-energy source and clean energy carrier. An improved simple algorithm ensuring the dual roles of pressure acting on velocity and density fields is developed to realize thermo-hydraulic completely-coupled modeling of a typical DSG loop with transient phase-change and multiple flow-patterns. The excitation-response characteristics of the loop were investigated under various step-variations of direct normal irradiance (DNI), inlet mass fiowrate (m(in)) and inlet temperature (t(in)). Increasing DNI (decreasing m(in)) is found to narrow the preheating-evaporation regions and expand the superheating region, and vice versa. While under step-variations of t(in), the evaporation region almost remains unchanged (about 403 m). The water slides to a lower temperature faster than climbs to a higher one under variations of DN1 (up to 670s vs. 2960s) and m(in) (up to 1184s vs. 4420s), simultaneously the outlet temperature (t(out)) staying a monotonical response-trend. However, under t(in) variations, t(out) holds a higher-order trait. The responses of both pressure and velocity are tightly coupled and always hold higher-order trait. The response time of the total mass in the loop is almost 2.5 to 5.5 times as fast as t(out). (C) 2018 Elsevier Ltd. All rights reserved.

关键词： Solar energy Concentrating solar power (CSP) Direct steam generation (DSG) Transient characteristics simple algorithm

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Numerical study for the assessment of pollutant dispersion from a thermal power plant under the different temperature regimes

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INTERNATIONAL JOURNAL OF ENVIRONMENTAL SCIENCE AND TECHNOLOGY 2019年第10期16卷 6089-6112页

作者： Issakhov, A. Mashenkova, A. Al Farabi Kazakh Natl Univ Alma Ata Kazakhstan Kazakh British Tech Univ Alma Ata Kazakhstan

In this paper, numerical simulation of motion and dispersion of pollutant emissions into the atmosphere under real atmospheric conditions were considered. To solve this problem, a system of Reynolds-averaged Navier-Stokes equations was used, and the standard k-epsilon and SST k-omega turbulence models were used to close this system of equations. Moreover, the test problem was solved numerically to verify the mathematical model and numerical algorithm. The obtained numerical results were compared with the experimental data and modeling results of well-known authors. A proven mathematical model and numerical algorithm was used to describe the process of pollutant emissions from Ekibastuz SDPP (Ekibastuz State District power plant) chimneys and the spread of CO2 in the air flow field under real atmospheric conditions. For this problem, four different speed regimes (the first-0.5 m/s and 1 m/s, the second-1 m/s and 1.5 m/s, the third-2 m/s and 4 m/s, and the fourth-4 m/s and 5 m/s), as well as three different temperature regimes (constant temperature, decrease temperature, and temperature inversion) were considered.

关键词： Reynolds-averaged Navier-Stokes (RANS) Jet in crossflow Pollutant dispersion simple algorithm Temperature inversion

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Modelling of Flow-Shear Coupling Process in Rough Rock Fractures Using Three-Dimensional Finite Volume Approach

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ROCK MECHANICS AND ROCK ENGINEERING 2019年第11期52卷 4693-4713页

作者： Karimzade, Ebrahim Seifabad, Masoud Cheraghi Sharifzadeh, Mostafa Baghbanan, Alireza Isfahan Univ Technol Dept Min Engn Esfahan Iran Curtin Univ Western Australian Sch Mines Dept Min & Met Engn Bentley WA Australia

A computational code has been developed based on finite-volume method (FVM) to investigate fluid flow-through roughwalled rock fractures during shear processes, considering evolutions of aperture and contact area with shear displacement. In the code, the full 3-D Navier-Stokes equation is solved in a cell-centered collocated variable arrangement and the pressure-velocity coupling is performed using the simple algorithm. A series of coupled shear-flow tests under constant normal stress of 3 MPa with different shear displacements of 1-10 mm were conducted and their results were compared with numerical simulations results. The comparison shows good agreement between the simulated and measured results. Aperture distribution during shear was evaluated by superimposing the upper and lower fracture surfaces according to the initial aperture and dilation at different shear displacements. The results show that contact area evolution dominates the variations of flow rate as well as flow pattern in a rough fracture. In addition, there is a linear relationship between aperture coefficient of variation and contact area ratio during shear. The simulation results also demonstrate the deviation of velocity profiles from the ideal parabolic form in some regions due to the formation of eddy flows. This behavior may have been caused by the inertial effects, which can be characterized by the Navier-Stokes equation, while some simplified equations such as Reynolds equation or Stokes equation cannot capture these effects.

关键词： Rough-walled rock fracture 3-D Navier-Stokes Contact area evolution Finite-volume method simple algorithm

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Numerical analysis of the buckling and recuperation dynamics of flexible filament using an immersed boundary framework

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INTERNATIONAL JOURNAL OF HEAT AND FLUID FLOW 2019年 77卷 256-277页

作者： Kanchan, Mithun Maniyeri, Ranjith NITK Biophys Lab Dept Mech Engn Mangalore 575025 Karnataka India

The dynamics of flexible filaments in viscous shear flow is of interest to biologists and engineers in a wide variety of applications involving folding and unfolding sequence of long-chain biomolecules like DNA, non-motile sperm and microalgae. It is also helpful in understanding the deformation of natural and synthetic fibers which can be applied in areas such as biotechnology. In the present work, deformation and migration behavior of non-motile unicellular phytoplankton diatoms subjected to viscous shear flow are considered. These unicellular diatoms develop into colonies which are made up of linked chains. The complex fluid-structure interaction is solved by developing a two-dimensional numerical model with an immersed boundary framework. The simulation consists of suspending an elastic filament mimicking a diatom chain in a shear flow at low Reynolds number. The governing continuity and Navier-Stokes equations are solved on a Cartesian grid arranged in a staggered manner. A forcing term is added to the momentum equation that incorporates the presence of flexible filament in the fluid domain. The discretization of the governing equation is based on a finite volume method, and a simple algorithm is used to compute pressure and velocity. A computer code is developed to perform numerical simulations, and the model is first verified with the deformation study of a tethered flexible filament in uniform fluid flow. Next, the shape deformations for flexible filament placed freely in shear flow are compared with the studies of previous researchers. Further, the present results are validated with Jeffery's equation for particles immersed in shear flow along with classification plot for filament orbit regimes. All of these comparisons provide a reasonable validity for the developed model. The effect of bending rigidity and shear rate on the deformation and migration characteristics is ascertained with the help of parametric studies. A non-dimensional parameter called Visc

关键词： Diatom chains Finite volume method Immersed boundary method Low Reynolds number Viscous flow forcing simple algorithm

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A numerical framework for the one-dimensional modelling of refrigerator components 25

A numerical framework for the one-dimensional modelling of r...

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25th International Congress of Refrigeration (IIR)

作者： Lorbek, Luka Kitanovski, Andrej Univ Ljubljana Fac Mech Engn Ljubljana 1000 Slovenia

ISBN: (纸本)9782362150357

This paper presents the development of a numerical framework intended for the modelling of refrigerant flow in components where a one-dimensional pipe flow can be presumed. The goal is to maintain a single modelling paradigm for multiple components. In a vapour-compression system these are the capillary tube, the condenser and the evaporator. The governing equations are discretized according to the finite-volume method and solved with a modified simple algorithm capable of modelling compressible, phase-changing flow. Test cases were set up and the results show that it is possible to model all three components within a single numerical framework, thus eliminating the need for separate models.

关键词： Numerical framework Numerical modelling Capillary tubes Evaporator Condenser simple algorithm

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Aerodynamic Analysis of a Flapping Transitional Configuration

Aerodynamic Analysis of a Flapping Transitional Configuratio...

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AIAA Aviation Forum and Exposition

作者： Santarpia, Enrico Demasi, Luciano Nguyen, Nhan T. San Diego State Univ Dept Aerosp Engn San Diego CA 92182 USA Univ Calif San Diego Dept Struct Engn La Jolla CA 92093 USA NASA Ames Res Ctr Intelligence Syst Div Moffett Field CA 94035 USA

ISBN: (数字)9781624105890

ISBN: (纸本)9781624105890

The present work introduces the concept of Flapping Transitional Configuration, a system which combines fixed and flapping wing-borne flight. The external part of the wing oscillates with a possible increase in the performance in terms of lift and drag. The twisting effect observed in the flight of birds is partially included with the use of a trailing-edge flap capable of oscillating independently. This configuration can be used in small aircraft, and the flapping flight system can be activated during off-design conditions (e.g take-off). Two-dimensional unsteady computational fluid dynamic simulations are performed to evaluate the effectiveness of the new concept.

关键词： Flapping Frequency Trailing Edge Flap Lift Coefficient VTOL Aircraft Strouhal Number Vertical Takeoff and Landing simple algorithm Free Stream Velocity Wing Configurations High Lift Device

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Natural convection and entropy generation analysis inside a channel with a porous plate mounted as a cooling system

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THERMAL SCIENCE AND ENGINEERING PROGRESS 2018年 6卷 186-193页

作者： Maskaniyan, Mahla Nazari, Mohsen Rashidi, Saman Mahian, Omid Univ Shahrood Mech Engn Dept Shahrood *** Iran Ferdowsi Univ Mashhad Dept Mech Engn Mashhad 917751111 Razavi Khorasan Iran Ferdowsi Univ Mashhad Ctr Adv Technol Mashhad Razavi Khorasan Iran Beihang Univ Sch Aeronaut Sci & Engn Beijing 100191 Peoples R China

Natural convection heat transfer and entropy generation analysis inside a channel with a porous plate mounted at the bottom wall is investigated numerically. The effects of porous plate on the heat transfer improvement and entropy generation are studied in details. simple algorithm has been used to solve the set of algebraic discretized coupled equations. The ranges of Darcy number (Da), porosity (epsilon), and porous plate widths (delta) are 10(-2)-10(-6), 0-1, and 0-0.3, respectively. It is observed that for heat transfer augmentation goals, a porous medium with high permeability and high thermal conductivity is suggested. Moreover, the maximum temperature and velocity gradients are occurred at the upper half of the domain and this causes higher viscous and thermal entropy generations in this region.

关键词： Natural convection Porous plate Entropy generation Darcy number simple algorithm

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Stratospheric Drogue Instability Analysis

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JOURNAL OF AIRCRAFT 2018年第6期55卷 2524-+页

作者： Levy, Joseph C. Giannelis, Nicholas F. Thornber, Ben Vio, Gareth A. Univ Sydney Sch AMME Sydney NSW 2006 Australia

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