Special Issue "EFD and Heat Transfer III"

Submission Deadline: 15 June 2021 (closed)
Guest Editors
Zhigang Fang, Wuhan University of Technology, China

Summary

This special issue is devoted to the discussion of recent developments and applications of engineering fluid mechanics and heat transfer.

 

Fluid mechanics is a discipline based on potential flow equations, Euler equations, and Navier-Stokes equations, the development of computer provides theoretical and experimental verification basis for engineering fluid mechanics, and EFD is widely used in the design of aircraft and fluid machinery. Heat transfer studies the transmission patterns of heat energy caused by temperature difference. As theoretical and experimental research continue to close its gaps with production and life, microscale heat transfer, phase change of biological heat transfer, multiphase flow heat transfer, low-temperature heat transfer, and many other interdisciplinary studies and subdisciplines were derived therefrom.

 

In recent years, with the development of micromachining and the growing demand for miniaturization of industrial products, microscale heat transfer has become a hot topic in the research of engineering thermophysics. Related professional experts, researchers, graduate students are welcome to join us in the following topics:

 

1) Aerodynamics, such as aircraft wing design, automotive body design;

2) Fluid-solid coupling analysis;

3) Thermodynamics and heat transfer, such as thermal analysis during engine combustion;

4) Fluid theory method, such as Navier-Stokes equations;

5) Postprocessing and model validation, including Statistical Learning and Uncertainty Quantification.


Keywords
Engineering Fluid Mechanics; Heat Transfer; Aerodynamics; Thermodynamics.

Published Papers
  • A Genetic Algorithm for Optimizing Yaw Operation Control in Wind Power Plants
  • Abstract A genetic algorithm is proposed to optimize the yaw control system used for the stable and efficient operation of turbines in wind power plants. In particular, the factors that produce yaw static deviation are analyzed. Then, the sought optimization method for the yaw static deviation of the wind turbine is implemented by using a lidar wind meter in the engine room in order to solve the low accuracy problem caused by yaw static deviation. It is shown that fuzzy control can overcome problematic factors such as the randomness of wind direction and track the change of wind direction accurately. Power… More
  •   Views:317       Downloads:279        Download PDF

  • Intelligent Control of Cabin Environment Using Computational Fluid Dynamics for Intelligent Manufacturing
  • Abstract An efficient and versatile intelligent algorithm is developed for the control of the cabin environment of wind power generators. The method can be used to monitor and solve wind power generation problems at the same time. It also provides several advantages with respect to other traditional methods which imply significant workload and maintenance personnel. The functional requirements of the intelligent control system are analyzed, and a control algorithm for the stepping motor is selected and evaluated. Through the comparative analysis of the active power and internal temperature curve for three kinds of output power of the prototype, it is proved… More
  •   Views:309       Downloads:265        Download PDF

  • Optimal Scheduling of Electrical Energy Systems Using a Fluid Dynamic Analogy
  • Abstract The electricity-gas transformation problem and related intrinsic mechanisms are considered. First, existing schemes for the optimization of electricity-gas integrated energy systems are analyzed through consideration of the relevant literature, and an Electricity Hub (EH) for electricity-gas coupling is proposed. Then, the distribution mechanism in the circuit of the considered electricity-gas integrated system is analyzed. Afterward, a mathematical model for the natural gas pipeline is elaborated according to the power relationship, a node power flow calculation method, and security requirements. Next, the coupling relationship between them is implemented, and dedicated simulations are carried out. Through experimental data, it is found that… More
  •   Views:291       Downloads:273        Download PDF

  • How Do Water Filled Traffic Barriers Shake a Suspension Bridge?
  • Abstract The present study stems from the realization that the general problem relating to the analysis of wind-induced vibrations in suspension bridges still requires significant attention. Sidewalk railings, overhaul tracks, and deflectors are known to largely affect such dynamics. Here, the influence of a row of water-filled traffic barriers on the response of a sample suspension bridge is investigated numerically. It is shown that the existence of water barriers causes flow separation and non-negligible vortices with respect to the condition with no water barriers. The vortex shedding frequency at the far end is around 41.30 Hz, relatively close to the real… More
  •   Views:359       Downloads:266        Download PDF

  • Optimization of the Air Deck Blasting Parameters on the Basis of the Holmquist-Johnson-Cook Constitutive Model
  • Abstract The present study considers the so-called air deck blasting, one of the most commonly used techniques for the improvement of blasting efficiency in mining applications. In particular, it aims to improve the operating conditions of large-scale equipment, increase the efficiency of the slope enlarging process, and reduce the mining cost. These objectives are implemented through a two-fold approach where, first, a program for slope enlarging based on the middle air-deck charge blasting-loosening technology is proposed, and second, the physical mechanism responsible for the stress wave attenuation in the rock is analyzed in the framework of a Holmquist–Johnson–Cook constitutive model. Field… More
  •   Views:461       Downloads:402        Download PDF

  • Experimental Study on Seepage Characteristics of a Soil-Rock Mixture in a Fault Zone
  • Abstract A mixture of fault gouge and rubble taken out from a fault zone is used to prepare a S-RM (Soil-Rock Mixture) sample with rock block proportions of 20%, 30%, 40%, 50%, 60% and 70%, respectively. A GDS triaxial test system is used accordingly to measure the seepage characteristics of such samples under different loading and unloading confining pressures in order to determine the variation law of the permeability coefficient. The test results show that: (1) The permeability coefficient of the S-RM samples decreases as the pressure increases, and the decrease rate of this coefficient in the initial stage of confining… More
  •   Views:462       Downloads:435        Download PDF

  • Analysis of the Microstructure and Macroscopic Fluid-Dynamics Behavior of Soft Soil after Seepage Consolidation
  • Abstract The purpose is to study the microstructure and macroscopic fluid-dynamic behavior of soft soil after it has been subjected to a seepage consolidation procedure. First, the microscopic pore structure of soft clay is quantitatively studied by a scanning electron microscope technique. Second, the average contact area rate of soil particles is obtained employing statistical analysis applied to microscopic images of soft soil, and the macroscopic porosity of soft clay is determined through an indoor geotechnical test. Finally, mathematical relationships are introduced by fitting the results of the test. The results show that the unmodified empirical equation for the permeability coefficient… More
  •   Views:460       Downloads:418        Download PDF

  • Application of the Navier-Stokes Equations to the Analysis of the Landslide Sediments Permeability and Related Seepage Effects
  • Abstract The purpose of the study is to implement a new model based on the Navier-Stokes equations for the characterization of landslide sediments interacting with a moving fluid. The model is implemented by combining Hypermesh, the LS-DYNA software and MATLAB. The results show that the main factors affecting the permeability of landslide sediments are the genetic mechanism, the structure and composition of materials, material lithology, and stress. The characteristics and mechanism of permeability changes are determined by adjusting the water levels of fluids. It is found that the permeability of landslide sediments increases at the front and decreases in the middle… More
  •   Views:456       Downloads:449        Download PDF

  • CFD Analysis of Fluid-Dynamic and Heat Transfer Effects Generated by a Fixed Electricity Transmission Line Interacting with an External Wind
  • Abstract The flow past a fixed single transmission conductor and the related heat transfer characteristics are investigated using computational fluid dynamics and a relevant turbulence model. After validating the method through comparison with relevant results in the literature, this thermofluid-dynamic problem is addressed considering different working conditions. It is shown that the resistance coefficient depends on the Reynolds number. As expected, the Nusselt number is also affected by Reynolds number. In particular, the Nusselt number under constant heat flux is always greater than that under a constant wall temperature. More
  •   Views:461       Downloads:440        Download PDF

  • Analysis of the Heat Transfer Efficiency of an Automobile Engine under Different Grille Opening and Closing Conditions
  • Abstract Computational Fluid Dynamics is used to assess the thermal (heat transfer) performances of an automobile engine considering different grille opening and closing degrees. For this purpose the entire vehicle is modelled and three fundamental aspects are examined, namely, the open area of the air intake grille, the position of the upper and lower grilles and their shape. The results show that the opening area and position of the grille have some influence also on the aerodynamic characteristics of the automobile. With an increase in the opening angle of the grille, the CD (Drag Coefficient) value of the whole vehicle becomes… More
  •   Views:433       Downloads:411        Download PDF

  • Optimization of the Internal Circulating Fluidized Bed Using Computational Fluid Dynamics Technology
  • Abstract The computational fluid dynamics (CFD) technology is analyzed and calculated utilizing the turbulence model and multiphase flow model to explore the performance of internal circulating fluidized beds (ICFB) based on CFD. The three-dimensional simulation method can study the hydrodynamic properties of the ICFB, and the performance of the fluidized bed is optimized. The fluidization performance of the ICFB is improved through the experimental study of the cross-shaped baffle. Then, through the cross-shaped baffle and funnel-shaped baffle placement, the fluidized bed reaches a coupled optimization. The results show that CFD simulation technology can effectively improve the mass transfer efficiency and performance… More
  •   Views:523       Downloads:420        Download PDF

  • Thermal Analysis by Means of Differential Scanning Calorimetry of the Characteristic Thermodynamic Temperatures of a Cu-Zr-Al Bulk Metallic Glass
  • Abstract In this study a Cu43Zr48Al9 bulk metallic glass prepared by the copper mold casting method is considered. In recent years, Cu-Zr-Al systems like this have enjoyed widespread attention due to their high strength, high hardness, high corrosion resistance and low cost. Here samples of this substance are studied using DSC (Differential scanning calorimetry) to determine the effect of different test conditions (heating rate, sample mass, sample specific surface area and sample crystal phase) on the characteristic thermodynamic temperature of the bulk metallic glass. Experimental results show that almost all of the five characteristic thermodynamic temperatures (Tg, Tx, Tp, Tm, Tl)… More
  •   Views:489       Downloads:453        Download PDF

  • Numerical Simulation of Wake Vortices Generated by an A330-200 Aircraft in the Nearfield Phase
  • Abstract In order to overcome the typical limitation of earlier studies, where the simulation of aircraft wake vortices was essentially based on the half-model of symmetrical rectangular wings, in the present analysis the entire aircraft (a typical A330-200 aircraft) geometry is taken into account. Conditions corresponding to the nearfield phase (take-off and landing) are considered assuming a typical attitude angle of 7° and different crosswind intensities, i.e., 0, 2 and 5 m/s. The simulation results show that the aircraft wake vortices form a structurally eudipleural four-vortex system due to the existence of the sweepback angle. The vortex pair at the outer side… More
  •   Views:497       Downloads:492        Download PDF

  • CFD-Based Numerical Analysis of the Thermal Characteristics of an Electric Vehicle Power Battery
  • Abstract Towards the end to solve the problem of temperature rise in the power battery of electric vehicles, a method based on the coupling of electrochemical, thermal and hydrodynamic aspects is implemented. The method relies on the COMSOL Multiphysics software, which is used here to simulate the thermal behaviour, the related fluid-dynamics and the life attenuation of the power battery. A 3D battery model is built assuming a cylindrical geometry. The diameter of the battery is 18 mm, and its length is 65 mm. The battery charges and discharges at 3C, and the initial temperature is 25°C. Intake flow is set to 0.5 m/s… More
  •   Views:492       Downloads:499        Download PDF

  • Using Image Processing Technology and General Fluid Mechanics Principles to Model Smoke Diffusion in Forest Fires
  • Abstract In the present study, the laws of smoke diffusion during forest fires are determined using the general principles of fluid mechanics and dedicated data obtained experimentally using an “ad hoc” imaging technology. Experimental images mimicking smoke in a real scenario are used to extract some “statistics”. These in turn are used to obtain the “divergence” of the flow (this fluid-dynamic parameter describing the amount of air that converges to a certain place from the surroundings or vice versa). The results show that the divergence of the smoke depends on the outside airflow and finally tends to zero as time passes.… More
  •   Views:649       Downloads:583        Download PDF

  • CFD Analysis of the Influence of Ionic Liquids on the Performances of a Refrigeration System
  • Abstract The falling film of an ionic liquid ([EMIM] [DMP] + H2O) and its effect on a refrigeration system are numerically simulated in the framework of a Volume of Fluid (VOF) method (as available in the ANSYS Fluent computational platform). The properties of the liquid film and the wall shear stress (WSS) are compared with those obtained for a potassium bromide solution. Different working conditions are considered. It is noted that the ionic liquid demonstrates a better absorption capability, with a coefficient of performance (COP) of 0.55. It is proved that the [EMIM] [DMP] + H2O ionic liquid working substance is… More
  •   Views:758       Downloads:682        Download PDF

  • On the Stability of Carbon Shale Slope under Rainfall Infiltration
  • Abstract Carbonaceous shale is a sedimentary rock containing a large amount of dispersed carbonaceous organic material. It is easy to crack and soften when exposed to water. In the present work, the stability of such a rock and its sensitivity to the formation of infiltrations due to rainfall are analyzed numerically using the GeoStudio software. The slope stability coefficient is calculated and verified using the landslide thrust calculation method. The results show that under the action of heavy rainfall, water infiltrates into the slope layer by layer, and, accordingly, the soil volume water content is different with respect to that typical… More
  •   Views:601       Downloads:585        Download PDF

  • Analysis of the Thermal Behavior of a Lithium Cell Undergoing Thermal Runaway
  • Abstract This study examines the thermal runaway of a lithium ion battery caused by poor heat dissipation performances. The heat transfer process is analyzed on the basis of standard theoretical concepts. Water mist additives are considered as a tool to suppress the thermal runaway process. The ensuing behaviour of the battery in terms of surface temperature and heat generation is analyzed for different charge and discharge rates. It is found that when the remaining charge is 100%, the heat generation rate of the battery is the lowest, and the surface temperature with a 2C charge rate is higher than that obtained… More
  •   Views:840       Downloads:821        Download PDF

  • A study on the Gas-based Lubrication of Elastic Foil Bearings Using an Over Relaxation Iteration Method
  • Abstract A new type of foil bearings with a specific surface microstructure is studied. First, relevant boundary conditions based on the assumption of rarefied gas flow are proposed, then, the static bearing capacity and friction torque are analyzed in the framework of a numerical technique based on the discretization of the governing equation for rarefied gas-dynamics. It is shown that under the same static load, the difference between the minimum film thickness calculated in this exploration and the results provided by dedicated tests is not obvious; with an increase in the load, the simulation results are closer to the test values;… More
  •   Views:766       Downloads:695        Download PDF

  • Analysis of the Flow Field Characteristics Associated with the Dynamic Rock Breaking Process Induced by a Multi-Hole Combined External Rotary Bit
  • Abstract The characteristics of the flow field associated with a multi-hole combined external rotary bit have been studied by means of numerical simulation in the framework of an RNG k-ε turbulence model, and compared with the results of dedicated rock breaking drilling experiments. The numerical results show that the nozzle velocity and dynamic pressure of the nozzle decrease with an increase in the jet distance, and the axial velocity of the nozzle decays regularly with an increase in the dimensionless jet distance. Moreover, the axial velocity related to the nozzle with inclination angle 20° and 30° can produce a higher hole… More
  •   Views:942       Downloads:832        Download PDF

  • CFD Analysis and Optimization of an Engine with a Restrictor Valve in the Intake System
  • Abstract In some competitions the rules clearly state that all participating cars must install a restrictor valve structure in the intake system of the engine. The intake air volume of the engine is considerably affected due to the existence of such a valve. Indeed, a small interface diameter through which gas flows can lead to considerable flow resistance and loss. In this study, a four-cylinder engine for FSC racing is analyzed using a combined method based on numerical simulation and experiments. The analysis reveals that the main factors affecting the intake air volume are the intake manifold and the volume of… More
  •   Views:875       Downloads:998        Download PDF

  • A Research on the Flow Characteristics of a Splitter-Based Water Cooling System for Computer Boards
  • Abstract The splitter is an important component of water-based cooling systems used to extract heat from computer boards. In the present study, the flow characteristics of a 16-splitter structure were numerically simulated and compared with experimental results to verify the reliability of the numerical simulation method. Accordingly, the concept of splitter structural coefficients was proposed. Based on the results of this study, we recommend a selection range of 5 ≤ k ≤ 6 for the structure factor k of the splitter; after optimization, the maximum deviation of the splitter outlet flow was reduced from the original value of 100% to 8.3%. More
  •   Views:841       Downloads:778        Download PDF