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  • Numerical Simulation of Entropy Generation in Hydrogen-Air Burner
  • Abstract The aim of this work is the numerical simulation of the combustion of hydrogen with air in a burner and the numerical solution of local entropy generation rate in the combustion chamber. The effects of equivalence ratio φ and oxygen percentage γ on combustion and entropy generation rates are studied for different φ(ranging from 0 to 1.0) and γ values (ranging from 10 to 30%). The predictions show that the increase of φ (or the decrease of λ ) reduces notably the reaction rate levels. The equations of continuity, of energy and momentum are solved by volume finite using commercial…
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  • Fluid dynamic analysis of different Yacht configurations with VOF method
  • Abstract This paper presents two applications of Computational Fluid Dynamics (CFD) to super and mega yacht design, based on the Volume of Fluid method. After an overview of recent literature on the subject, the analysis of the hydrodynamic performances of different hull configurations and of different appendage configurations is presented.
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  • Preliminary Validation of Fluid-Structure Interaction Modeling for Hypersonic Deployable Re-Entry Systems
  • Abstract The aim of the present work is to provide a first attempt to set an aero-thermo-elastic methodology for deployable atmospheric re-entry decelerators operating at high Mach number and high dynamic pressure. Because of the severity of re-entry conditions such as high temperatures, high pressures and high velocities, the behavior of their flexible structures is a hard target to assess. In this paper a partitioned Fluid Structure Interaction (FSI) approach based on the integration of different commercial software (STAR-CCM+ and ABAQUS) is presented. In order to validate the specific codes and the overall strategy for structural and fluid dynamics analyses of…
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  • Natural Convection in a Square Cavity Filled with Nanofluids
  • Abstract The present paper deals with a numerical study of natural convection in a square cavity filled with a nanofluid. The left and right vertical walls of the cavity are maintained at a local temperature Th (heat source) and a local cold temperature TC, respectively. Horizontal walls are assumed to be adiabatic. The governing equations are discretized by using the finite volume method and solved by the SIMPLER algorithm. Our computer fortran code is validated through comparison with numerical results found in the literature. Results are presented in terms of streamlines, isotherms, local and average Nusselt numbers for the Rayleigh number…
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  • A Practical Engineering Approach to the Design and Manufacturing of a mini kW BladeWind Turbine: Definition, optimization and CFD Analysis
  • Abstract A practical engineering approach to the design of a 60 kW wind generator with improved performances is presented. The proposed approach relies on the use of a specific, "ad hoc'' developed software, OPTIWR (Optimization Software), expressly conceived to define an "optimum'' rotor configuration in the framework of the blade-element-momentum theory. Starting from an initial input geometric configuration (corresponding to an already existing 50 kW turbine) and for given values of the wind velocity Vwind and of the advance ratio X = Vwind/ΩR (where Ω is the blade rotational speed and R is the propeller radius), this software is used to…
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  • Dynamics of Free Liquid Jets Affected by Obstructions at the Jet Entrance
  • Abstract Free liquid jets are of great technical importance in a variety of applications like ink-jet printing, glass painting, spray coating and metal cutting. Here we consider the changes induced in the dynamics of such jets by the presence of obstructions at the tube exit. Using stainless steel bars of 1.5 mm diameter as obstruction objects and aqueous solutions of glycerol of varying concentrations as working fluids, we performed experiments for different configurations, including a single rod at the centre of the tube exit, two parallel rods equidistant from the centre of the tube, and a 10 mesh screen. Images of…
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  • On the Formation Mechanism and Characteristics of High-Pressure Percussion Pulsed Water Jets
  • Abstract Although the socalled percussion-pulsed-water jet technique is currently recognized as an effective means for breaking hard rocks, it can’t be extensively employed due to insufficient systematic research on the related flow-field structure. Considered as one of the rock breaking technologies with the highest potential of development and application, this method is characterized by water hammer effects, a high-frequency impact pressure and high-speed side flows. The typical (impact and extrusion) pistons used for this technique collide several times to form the multi-pulsed jet. Here we analyze these features through a combined experimental-numerical investigation. The number of pulses and kinetic parameters of…
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  • Numerical Simulation of Droplet Breakup, Splitting and Sorting in a Microfluidic Device
  • Abstract Droplet generation, splitting and sorting are investigated numerically in the framework of a VOF technique for interface tracking and a finite-volume numerical method using the commercial code FLUENT. Droplets of water-in-oil are produced by a flow focusing technique relying on the use of a microchannell equipped with an obstacle to split the droplets. The influence of several parameters potentially affecting this process is investigated parametrically towards the end of identifying "optimal" conditions for droplet breakup. Such parameters include surface tension, the capillary number and the main channel width. We show that the capillary number plays a crucial role in determining…
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  • A Experimental Study on the Rhelogical and Mechanical Properties of Blends of Polyethylene and Modified Oil Shale Ash (MOSA)
  • Abstract Blends of Polyethylene (PE) and modified-oil shale ash (MOSA) with different fractions of MOSA were prepared by the melting blend method. The effects of MOSA content on the rheological and mechanical properties of the blend were properly assessed via direct experimental analysis (more precisely, all rheological measurements were performed using a laboratory-scale XSS-300 torque rheometer with single screw extruder; the temperatures were maintained at 170°C, 180°C and 190°C under continuous extrusion). The prepared samples were observed to display a shear-thinning behaviour. Moreover, with increasing the MOSA content, we found the yield strength of the blends to increase, while its elongation…
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