Vol.16, No.4, 2020-Table of Contents
  • Shock-Wave/Rail-Fasteners Interaction for Two Rocket Sleds in the Supersonic Flow Regime
  • Abstract Rocket sleds belong to a category of large-scale test platforms running on the ground. The applications can be found in many fields, such as aerospace engineering, conventional weapons, and civil high-tech products. In the present work, shock-wave/rail-fasteners interaction is investigated numerically when the rocket sled is in supersonic flow conditions. Two typical rocket sled models are considered, i.e., an anti-D shaped version of the rocket sled and an axisymmetric slender-body variant. The dynamics for Mach number 2 have been simulated in the framework of a dynamic mesh method. The emerging shock waves can be categorized as head-shock, tailing-shock and reflected-shock.… More
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  • Determination of the Circulation for a Large-Scale Wind Turbine Blade Using Computational Fluid Dynamics
  • Abstract The determination of the circulation for wind turbine blades is an important problem in engineering. In the present study, we develop a specific approach to evaluate the integral that represents mathematically the circulation. First the potentialities of the method are assessed using a two-dimensional NACA64_A17 airfoil as a testbed and evaluating the influence of different integration paths and angles of attack on the circulation value. Then the method is applied to blades with different relative heights in order to provide useful reference data to be used for the optimization and reverse design of wind turbine blades. As shown by the… More
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  • Dynamic Simulation Analysis of the Working Device of a ZL50 Loader
  • Abstract In this study, assuming a certain type of wheel loader as the main objective of the research, the performances of the working device of the loader are investigated on the basis of an in-house code. After creating a three-dimensional model of the working device using Solidworks, this model has been imported into the dynamic simulation software ADAMS, and the simulation problem has been completed by adding the relevant constraints and loadings. The load stress curve relating to the main connecting point of the working device has been obtained in the frame work of this approach and it has been shown… More
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  • Preparation and Optimization of High-Purity Silicon Carbide Magnetic Abrasives for the Magnetic Induction-Wire Sawing Process
  • Abstract In this study, magnetic abrasives were obtained by crushing and sieving sintered iron-silicon carbide (Fe-SiC) composites. Fe and SiC powders with different mesh numbers were pre-compacted using different pressures and then sintered at various temperatures and with different holding times. The dispersion uniformity of the SiC powder was improved through surface modification using polyethylene glycol (PEG) 300. The resulting magnetic abrasives were characterized in terms of phase composition, density, relative permeability, and microstructure; this was followed by a comprehensive analysis to reveal the optimal processing parameters. The ideal combination of process parameters for preparing SiC magnetic-abrasive grains for the magnetic… More
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  • Spreading of a Multicomponent Drop in Water: Solutions and Suspensions
  • Abstract The distribution of material resulting from the impact of a freely falling drop with a target liquid has been studied by photo and video registration methods. Different cases have been investigated by considering drops made of aqueous solutions (ink, salt, acid) and including fine solid particles (i.e., suspensions). New features have been observed in terms of flow dynamics and thin components produced as a result of the impact (such as banded elements, ligaments, and vortices at the surface of the liquid). In particular, the characteristics of emerging netlike structures have been found to depend on the size of the suspension… More
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  • Acoustic Shock Emission in a Collision of a Drop with Water Surface
  • Abstract The collision of droplets with a water surface is being actively developed in the interests of many applied problems—transfer of matter through the ocean-atmosphere boundary, underwater acoustic noise of the marine environment, measurement of precipitation intensity, various technologies, and much more. One of the research priorities is acoustic radiation, in particular, shock sound arising at the moment a drop contacts the surface. The impact of the drop is preceded by processes that affect the shape of the drop, because of which it noticeably deviates from the spherical one. As a result, the final (contact) velocity changes–one of the most important… More
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  • Oscillations of an Inviscid Encapsulated Drop
  • Abstract The problem relating to the small-amplitude free capillary oscillations of an encapsulated spherical drop is solved theoretically in the framework of asymptotic methods. Liquids are supposed to be inviscid and immiscible. The formulas derived are presented for different parameters of the inner and outer liquids, including densities, thickness of the outer liquid layer, and the surface and interfacial tension coefficients. The frequencies of oscillation of the encapsulated drop are studied in relation to several “modes” which can effectively be determined in experiments by photo and video analysis. The results are presented in terms of oscillation frequencies reported as a function… More
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  • Fast Superfine Components and Sound Packets in Phenomena Induced by the Impact of a Drop on a Target Fluid in Quiescent Conditions
  • Abstract The structure of the flow and the acoustic signals generated by the impact of a freely falling drop of water with an underlying quiescent fluid have been investigated for droplets having diameter 0.5 cm and a contact velocity in the range 1.5 < U < 5 m/s. The experimental study has been supported by high-resolution videos of the flow (as seen from above and from the side). The evolution of ejecta, spikes, droplets spray, cavity, splash, secondary cavity, streamer, secondary droplets and sequence of capillary waves is reported accordingly. In particular, perturbations of the smoothed free surface with transverse dimensions… More
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  • Complete Coalescence, Partial Bounce and Rebound: Different Regimes Resulting from the Interaction of a Free Falling Drop with a Target Fluid
  • Abstract The interaction of a falling drop (diluted aqueous solution of ink in various concentrations) with a target fluid (partially degassed tap water) has been tracked by means of high-resolution video recording and photography. The experimental setup has carefully been prepared in order to preserve the axial symmetry of initial conditions. Three regimes of interaction have been identified accordingly (depending on the drop velocity as controlled by the distance of fall): rapid droplet coalescence, rebound with the conservation of the drop volume and shape, and partial coalescence. Previous findings are recovered and confirmed, and enriched with heretofore unseen observations of complex… More
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  • Analysis of Gas-Solid Flow Characteristics in a Spouted Fluidized Bed Dryer by Means of Computational Particle Fluid Dynamics
  • Abstract In order to grasp the particle flow characteristics and energy consumption of industrial fluidized spouted beds, we conduct numerical simulations on the basis of a Computational Particle Fluid Dynamics (CPFD) approach. In particular, the traction model of Wen-Yu-Ergun is used and different inlet conditions are considered. Using a low-speed fluidizing gas, the flow state of the particles is better and the amount of particles accumulated at the bottom of the bed wall becomes smaller. For the same air intake, the energy loss of a circular nozzle is larger than that of a square nozzle. More
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  • The Elaboration of Flow Resistance Model for a Bag Filter Serving a 200 MW Power Plant
  • Abstract On the basis of a macro flow resistance method and the Darcy Theory, a mathematical model is elaborated to characterize the flow resistance of a bag filter serving a coal-fired power plant. The development of the theoretical model is supported through acquisition of relevant data obtained by scanning the micro structure of the bag filter by means of an electron microscope. The influence of the running time and boiler load on the flow resistance and the impact of the flow resistance on the efficiency of the induced draft fan are analyzed by comparing the results of on-site operation tests. We… More
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