Vol.16, No.5, 2020-Table of Contents
  • Numerical Simulation of Fire-Smoke Diffusion Caused by Vehicles in a Tunnel
  • Abstract Urban tunnels are generally narrow and fire smoke can hardly diffuse. In the present study, numerical simulation is used to analyze the diffusion of high temperature smoke produced by fire inside a specific tunnel (the Kaiyuan tunnel). The results are compared with similar data relating to other tests to determine the validity of the numerical method. Moreover, the critical velocity obtained by numerical simulation of 5 MW, 20 MW, and 50 MW fires in curved and linear sections of the considered tunnel is compared with the values obtained using empirical formulas. The results show that, for the tunnel ventilation design,… More
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  • Optimization of a Heat Exchanger Using an ARM Core Intelligent Algorithm
  • Abstract In order to optimize heat transfer in a heat exchanger using an ARM (advanced RISC machine) core intelligent computer algorithm, a new type of controller has been designed. The whole control structure of the heat exchange unit has been conceived on the basis of seven functional modules, including data processing and output, human-computer interaction, alarm, and data communication. The main controller and communication controller have been used in a combined fashion and a new MCU (micro control unit) system scheme has been proposed accordingly. A fuzzy controller has been designed by using a fuzzy control algorithm, and a new mode… More
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  • A Numerical Study of the Tip Wake of a Wind Turbine Impeller Using Extended Proper Orthogonal Decomposition
  • Abstract The behavior of the tip wake of a wind turbine is one of the hot issues in the wind power field. This problem can partially be tackled using Computational Fluid Dynamics (CFD). However, this approach lacks the ability to provide insights into the spatial structure of important high-order flows. Therefore, with the horizontal axis wind turbine as the main focus, in this work, firstly, we conduct CFD simulations of the wind turbine in order to obtain a data-driven basis relating to multiple working conditions for further analysis. Then, these data are studied using an extended Proper Orthogonal Decomposition (POD) algorithm.… More
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  • On the Application of the Lattice Boltzmann Method to Predict Soil Meso Seepage Characteristics
  • Abstract In this study, a two-dimensional approach is elaborated to study with the lattice Boltzmann method (LBM) the seepage of water in the pores of a soil. Firstly, the D2Q9 model is selected to account for the discrete velocity distribution of water flow. In particular, impermeability is considered as macroscopic boundary condition for the left and right domain sides, while the upper and lower boundaries are assumed to behave as pressure boundaries controlled by different densities. The micro-boundary conditions are implemented through the standard rebound strategy and a non-equilibrium extrapolation scheme. Matlab is used for the development of the related algorithm.… More
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  • Development of an Artificial Fish Swarm Algorithm Based on a Wireless Sensor Networks in a Hydrodynamic Background
  • Abstract The main objective of the present study is the development of a new algorithm that can adapt to complex and changeable environments. An artificial fish swarm algorithm is developed which relies on a wireless sensor network (WSN) in a hydrodynamic background. The nodes of this algorithm are viscous fluids and artificial fish, while related ‘events’ are directly connected to the food available in the related virtual environment. The results show that the total processing time of the data by the source node is 6.661 ms, of which the processing time of crosstalk data is 3.789 ms, accounting for 56.89%. The… More
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  • A Combined Experimental and Numerical Study of Shotcrete Jets and Related Wet Spray Nozzles
  • Abstract In this research, the dynamics of wet spray nozzles with different geometries, used to accelerate shotcrete, are investigated on the basis of a suitable three-dimensional mathematical model and related numerical method. Simulations have been conducted in the frame of the SIMPLEC algorithm. The k-ε turbulence model has been used to account for turbulent effects. The study shows that when the angle of the convergent section is less than 3°, it has a scarce effect on the dynamics of the jet of shotcrete; with the increase of the convergence angle, the shotcrete jet velocity decreases and the nozzle wear increases; when… More
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  • An Investigation into the Influence of the Airflow Path on the Convective Heat Transfer for an Eddy Current Retarder Turntable
  • Abstract In order to improve the convective heat transfer relating to an eddy current retarder, the finite element model has been used to assess the performances of different possible designs. In particular, assuming the steady running state of retarder as the working condition, flow and temperature fields have been obtained for the rotor. The influence of airflow path on heat dissipation has been analysed, and the influence of the temperature field distribution on the performance of retarder has been discussed accordingly. The results show that when the steady running state of the turntable is considered, the maximum temperature is lower, the… More
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  • A Novel Approach for the Numerical Simulation of Fluid-Structure Interaction Problems in the Presence of Debris
  • Abstract A novel algorithm is proposed for the simulation of fluid-structure interaction problems. In particular, much attention is paid to natural phenomena such as debris flow. The fluid part (debris flow fluid) is simulated in the framework of the smoothed particle hydrodynamics (SPH) approach, while the solid part (downstream obstacles) is treated using the finite element method (FEM). Fluid-structure coupling is implemented through dynamic boundary conditions. In particular, the software “TensorFlow” and an algorithm based on Python are combined to conduct the required calculations. The simulation results show that the dynamics of viscous and non-viscous debris flows can be extremely different… More
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  • A Model for the Optimization of the Shale Gas Horizontal Well Section Based on the Combination of Different Weighting Methods in the Frame of the Game Theory
  • Abstract Existing “evaluation indicators” are selected and combined to build a model to support the optimization of shale gas horizontal wells. Towards this end, different “weighting methods”, including AHP and the so-called entropy method, are combined in the frame of the game theory. Using a relevant test case for the implementation of the model, it is shown that the horizontal section of the considered well is in the middle sweet spot area with good physical properties and fracturing ability. In comparison with the FSI (flow scanner Image) gas production profile, the new model seems to display better abilities for the optimization… More
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  • A Numerical Investigation on the Characteristics of the Radial Force in a Cycloid Gerotor Pump
  • Abstract In order to improve the performances of a cycloid gerotor pump, the variations of the radial force induced by different rotating speeds and outlet pressures are analyzed numerically. Using the numerical simulations as a basis, an improved oil inlet and outlet groove structure is proposed. The results show that the radial force decreases with the decrease of the outlet pressure and of the rotor speed. Compared with the original model, the large-end oil inlet line and pressure line of the new oil groove are claw-shaped. This configuration can effectively weaken the pressure changes inside the gerotor pump and reduce accordingly… More
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  • On the Design and Optimization of a Clean and Efficient Combustion Mode for Internal Combustion Engines through a Computer NSGA-II Algorithm
  • Abstract In order to address typical problems due to the huge demand of oil for consumption in traditional internal combustion engines, a new more efficient combustion mode is proposed and studied in the framework of Computational Fluid Dynamics (CFD). Moreover, a Non-dominated Sorting Genetic Algorithm (NSGA-II) is applied to optimize the related parameters, namely, the engine methanol ratio, the fuel injection time, the initial temperature, the Exhaust Gas Re-Circulation (EGR) rate, and the initial pressure. The so-called Conventional Diesel Combustion (CDC), Homogeneous Charge Compression Ignition (HCCI) and the Reactivity Controlled Compression Ignition (RCCI) combustion modes are compared. The results show that… More
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  • A Multiphase Wellbore Flow Model for Sour Gas “Kicks”
  • Abstract This study presents a new multiphase flow model with transient heat transfer and pressure coupling to simulate HTHP (high temperature and high pressure) sour gas “kicks” phenomena. The model is intended to support the estimation of wellbore temperature and pressure when sour gas kicks occur during drilling operation. The model considers sour gas solubility, phase transition and effects of temperature and pressure on the physical parameters of drilling fluid. Experimental data for a large-diameter pipe flow are used to validate the model. The results indicate that with fluid circulation, the annulus temperature with H2S kicks is the highest, followed by… More
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  • Influence of the Axial Position of the Guide Vane on the Fluctuations of Pressure in a Nuclear Pump
  • Abstract The influence of the axial mount position of the guide vane on the pressure fluctuation in a nuclear pump (AP1000) is investigated. The characteristics of the three-dimensional flow inside the nuclear pump are analyzed by means of numerical simulation. Results indicate that when the axial relative distance between the guide vane and the pumping chamber is reduced, in conditions of “small flow,” the efficiency of the pump increases, the pressure inside the pumping chamber decreases, while the losses related to the guide vane grow. Under large flow conditions, as the efficiency of the pump decreases, the losses for the guide… More
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