Applied Mechanics and Materials Vols. 789-790

Abstract: The free oscillation of liquid droplet is one of the classical questions in science research, liquid drops play important role in a lot of engineering applications. Theory study of droplet oscillation mainly based on the linear method, this method is only adapted to the small-amplitude oscillatory motion of drops. Except the linear method used in this study, numerical method have been successfully applied in simulation of the free oscillation of liquid droplet. In this paper, the finite element method is used to investigate numerically the influence of viscoelasticity on the small-amplitude oscillation of drop of polymer solutions. A spatial discretization is accomplished by the finite element method, the time descretization is carried by the Crank-Nicolson method, and the arbitrary Lagangian-Eulerian (ALE) method is used to track the change of the interface. Numerical results are compared with the ones of linear theory. The behaviors of oscillation are found to depend on the viscosity and the stress relaxation time of viscoelastic fluid, the results of numerical simulation and linear theory are identical.

Abstract: Erosive wear is defined as material loss from surface due to impact of liquid and solid particles. This mechanism can be seen widely in the industry such in mining, valves, pipe and pump systems. Characteristics and wear amount of erosive wear is affected by different parameters like geometry, impact speed, impingement angle of the hard particles, solid-liquid rate, material hardness and toughness. To determine the effect of these parameters on erosive wear, a wear slurry tank is designed. Before the prototype design of the test tank, different geometrical parameters of the tank are analyzed using simulation software. By computational investigations, the 3-D flow in a liquid/solid (slurry) tank is established and analyzed. Aim of the mathematical analysis was to detect the effect of the tank design parameters on liquid impact velocity and distribution on the test specimen surface. According to the results, geometrical parameters of the tank such as; baffle width, propeller length, assembly position of the specimens in the slurry tank, the distance between the propeller and specimens are defined.

Abstract: In the present paper the third order finite-difference shock-capturing essentially non-oscillatory (ENO) scheme for a non-uniform grid has been developed. The design of the ENO scheme is based on the methodology for uniform grids. To construct the essentially non-oscillatory piecewise polynomial, the Newtoninterpolant of the third order degree is adapted for the non-uniform grid. Also, the implementation of the symmetrical form of the slope limiters on non-uniform meshes is examined. The efficiency of the developed algorithm is demonstrated by the numerical experiments on the simulation of the three-dimensional turbulent steady flowfield generated by the transverse hydrogen injection into the supersonic air cross-flow. The comparison with results on the uniform grid using the coordinate system transformation is done.

Abstract: In this paper the mass flow distribution in zig-zag cooled power transformer windings is shown to play a crucial factor to accurately predict the winding temperature. In order to enable thermo-hydraulic network models for transformer design, new correlations are derived for combining and dividing T-junctions and elbow configurations. Good correspondence is achieved in comparison with CFD simulation results for a zig-zag cooled power transformer winding.

Abstract: Journal fluid bearings are widely used in industry due to their static and dynamic behavior and their very low coefficient of friction. The technical requirements to improve the new technologies design are increasingly focused on the indicators of dependability of systems and machines. Then, it is necessary to develop a methodology to study the reliability of bearings in order to improve and to evaluate their design quality. Few works are referenced in literature concerning the estimation of the reliability of fluid journal bearings. This paper deals with a methodology to study the failure probability of a hydrodynamic journal bearing. An analytical approach is proposed to calculate static characteristics in using the Reynolds equation. The commonly methods used in structural reliability such as FORM (First Order Reliability Method), SORM (Second Order Reliability Method) and Monte Carlo are developed to estimate the failure probability. The function of performance bounding two domains (domain of safety and domain of failure) is estimated for several geometrical configurations of a hydrodynamic journal bearing (long journal bearings with the hypotheses of Sommerfeld, Gümbel and Reynolds, and a short journal bearing with the hypothesis of Gümbel).

Abstract: Hybrid power system presented in this work focuses on the combination of wind, solar, and energy storing systems for sustainable power generation. The output power of wind turbine is only available under a specific speed or higher. The solar energy varies hourly, daily and seasonally which depends on variation of solar irradiation. A generator-set with a battery bank can be integrated with the wind and PV-system to ensure the continuity of power supply for all conditions.The paper aims to model and simulate the transient and steady state behavior of a Solar-Wind hybrid power generation system together with energy storage bank. Besides, a supervisory power flow controller has been developed which determines a power source that is selected to operate in order to satisfy the load demand taking into account the sun irradiance and the wind speed. The energy storage bank may be used to store an excess of power from the renewable energy system (RES) that will be used when there is insufficient supplied power. If either the available power from the wind turbine or from the solar panels or both of them cannot satisfy the load demand the generator set system will be used to satisfy the load demand. The functionality of the presented Hybrid Power System has been successfully designed and simulated using Matlab/Simulink tool.

Abstract: Penetration efficiency reflects high speed projectile penetration ability with the impact velocity (>800m/s) variation. To further study the penetration efficiency engineering model, the physical and mechanical parameters that affect the penetration efficiency of high-speed projectiles penetrating into concrete target are analyzed, penetration efficiency dimensionless quantities are determined, such as projectile’s length to diameter ratio, projectile and target strength ratio, etc. The dimensionless equation of penetration efficiency is got by using the homogeneous principles of the laws of physics dimensionless. According to experimental data, a function of dimensionless penetration efficiency and dimensionless projectile speed is fitted. Finally, the model is verified by test, and the model calculations and experiment results agree well. The model obtained in this paper can estimate the projectile’s impact velocity when the penetration efficiency reaches the maximum, it would be a theoretical guidance for high speed penetration effects experiments.

Abstract: The cold flow field in a two dimensional cavity of supersonic combustor has been simulated numerically by using the compressible flow Navier-Stokes equation with the κ-ω SST turbulence model. The flow field structure of different cavity aft wall slope angle (16°,30° and 90°) , different fore aft wall height ratio (1 and 2) and different length depth ratio (3 and 5) are analyzed. The conclusions are as follows: As cavity aft wall slope angle decreases, the compression wave formed at cavity leading separation corner shifts into expansion wave, the shear layer moves into cavity gradually; As cavity fore aft wall height ratio increases from one to two, the expansion wave formed at cavity leading separation corner strengthens and there is no compression wave formed at;As cavity length depth ratio increases from three to five, the compression or expansion wave formed at cavity leading separation corner weakens, cavity bottom wall pressure tends to be constant and aft wall pressure rises.

Abstract: In the paper are presented the possibility of using axial and radial diffusion burner in rotary furnace. Both types of burners allow secondary air combustion, combustion quality measure is the ratio of primary and secondary flame. Experimental comparison of both types of burners has been performed with the high-revolution rotary furnace. On this basis, benefits have been identified and their use possibilities.

Abstract: Incineration is a Thermal Treatment Technology (3Ts) that could be expressed as the way to get rid of waste effectively with the reduction of its mass and volume. However, to control the combustion process efficiently, especially combustion temperature, with low energy content in Municipal Solid Waste (MSW), an additional fuel is needed and leads to increase of operating cost compared with other disposal option. High Temperature Air Combustion (HTAC) has been successfully demonstrated in a lab-scale incinerator for energy saving and pollutant reduction, especially NO_x. This article has the objective to design and manufacture the prototype scale High Temperature Air Incinerator with a capacity to treat MSW of 12 Ton per day. The system consists of an automatic feeding machine to feed the waste into the primary combustion chamber (PCC) where the combustion takes place. The push ram is used to push the burning waste and fall down to the lower hearth. Primary combustion air is supplied into PCC at the amount lower than the stoichiometric requirement to produce the combustible gas which is flown into the Secondary Combustion Chamber (SCC) located above PCC. Secondary combustion air is injected to react with combustible gas to convert to the product of complete combustion. A part of hot flue gas which is flew out from SCC is reverted and mixed with fresh air, in order to reduce oxygen concentration, before passing through the heat exchanger tube bundle which is placed inside SCC in order to exchange heat with hot flue gas. To manufacture the designed incinerator, the detail of materials used as well as the frabication method is explained. It has been shown that HTAC can be applied for thermal destruction of waste successfully, in term of energy saving and pollutant free. Benefits of this research work will promote the using of thermal treatment technology of dispose of MSW with lower operating cost and lower pollutants.