Applied Mechanics and Materials Vol. 315

Abstract: In this paper, two-dimensional laminar natural-convection heat transfer of air has been numerically solved by Cubic Interpolated Method known as CIP which is based on the Eulerian mesh grid generation. For this investigation a cavity has been selected as a geometry which is being heated from bottom of the cavity at three different positions, the sides of the cavity are cold and the top of the cavity is adiabatic and no heat exchange exist there. The cavity is being heated from three different position of the bottom which is equal in length and equal but in three different position of left, center and right in equally distance. The whole simulation takes place in two various Grasshof number and air has been taken as fluid inside cavity. Prantl number has been set to 0.7 throughout the simulation. Results are presented in the form of streamlines and isothermal plots inside the cavity. The results illustrate the heat for middle heated plate is distributed symmetrically through the cavity.

Abstract: Bio fuels based on vegetable oils offer the advantage being a sustainable, annually renewable source of automobile fuel. Despite years of improvement attempts, the key issue in using vegetable oil-based fuels is oxidation stability, stoichiometric point, bio-fuel composition, antioxidants on the degradation and much oxygen with comparing to diesel gas oil. Thus, the improvement of emissions exhausted from diesel engines fueled by biodiesel derived from palm oil is urgently required to meet the future stringent emission regulations. Purpose of this study is to explore how significant the effects of palm oil blending ratio on combustion process that strongly affects the vehicles performance and exhaust emissions. The engine speed was varied from 15003000 rpm, load test condition varied by Dynapack chassis dynamometer from 050% and palm oil blending ratio from 515vol% (B5B15). Increased blends of biodiesel ratio is found to enhance the combustion process, resulting in decreased the HC emissions with nearly equal of engine performance. The improvement of combustion process is expected to be strongly influenced by oxygenated fuel in biodiesel content.

Abstract: Wind represents the kinetic energy of the atmosphere. Wind energy is currently supplying as much as 1% of the world electricity used, and could supply as much as 20% of global electricity in power and can be created through the use of wind turbines. Wind turbine blade is the most promising technology for the production of energy by using wind energy. Good design of wind turbine blade depends on performance of increasing to generate electricity which related with drag coefficient , lift coefficient and turbulence kinetic energy. However, the efficiency of wind turbine blade could be predicted by simulation due to flow streamline on wind turbine blade. This paper discuss the result obtain from simulation in CFD using CFX on NACA 4412 and NACA 4415.

Abstract: This paper investigates the mechanical properties and forming capabilities of magnesium ZE10. Mechanical properties are observed by stress strain diagram. Three types of the samples are used which are machined from thin sheets of 0.8mm thickness in 0⁰, 45⁰, 90⁰ of the rolling direction (RD). The samples are then tested at different temperatures varying from room temperature (RT) to 400°C. The factors that are considered in tensile tests are Youngs modulus, Yield strength, Ultimate tensile strength and fracture strain. The later part of this paper is devoted to deep drawing tests in which specimen are drawn from room temperature to 250°C. In these tests variation of Limit Drawing Ratio (LDR) is investigated at different temperatures. The other parameters observed are drawing depth, punch force, blank holder force and their variation from room temperature to elevated temperature.

Abstract: In this paper, natural convection heat transfer from heated plate positioned in square cavity vertically and horizontally was studied. Thermal BGK lattice Boltzmann numerical scheme was applied. The simulation was launched for different aspect ratio A=0.4 and 0.6 at Grasshof numbers and . Air was chosen as working fluid (Pr=0.71). Good arrangement was obtained between the present work and pervious approach using finite volume method. It is found that convection upper side of plate is increase as Grasshof number is increased.

Abstract: High technology and affordable computers are highly demanded currently. Computers are much faster and with very high performance. This however resulted in short life cycle and there is a need for a system to manage used computer that is collected. The volume of end of life computer that will be generated in a developing country has been forecasted to be between 400-700 million units by the year 2016-2018. This paper reviews current the reverse logistic for end of life computer in Malaysia and how it will evolve in the near future.

Abstract: This paper presents an experimental investigation that employed the acoustic emission (AE) technology to monitor sand transportation in two-phase flow. This investigation was undertaken on two phase (air-sand) flow in a horizontal pipe for varying Superficial Gas Velocities (VSG). The objective of this research programme is to develop a simple, non-invasive technique for monitoring of sand particle concentration levels in multi-phase flow conditions. The experimental findings show that AE absolute energy can be correlated with the size of sand, number of sand particles and Superficial Gas Velocity (VSG).

Abstract: Two phase flow is a common phenomenon that exists in the petroleum and chemical engineering industrial fields. An important feature employed to describe two phase flow is the flow regime which varies depending on the individual velocities of the components within the two-phase flow. One of these regimes, the slug regime, can create significant pressure fluctuations that compromise the integrity of the transporting structure (pipes, separators, etc). This is in addition to other unwanted effects such as flooding at the receiving end, an increase in deposits of hydrates and corrosion. Under such circumstances the detection of the slug and its associated characteristics are vitally important to the operator. This experimental study looks into the application of Acoustic Emission (AE) technology for detecting slug velocity in two phase (gas/liquid) flow. It is verified that slug velocity can be determined by using acoustic emission sensors.

Abstract: The use of natural gas as an alternative fuels are motivated from the impact in deteriorating quality of air and the energy shortage from petroleum products. Through retrofitting, CI engine runs on CNG, will be able to reduce the negative impact mainly on the use of petroleum products. However, this required the modification of the combustion chamber geometry by reducing the compression ratio to value that suits combustion of CNG. In this present studies, four different shapes and geometries of combustion chamber were designed and simulate using CFD package powered by Ansys workbench, where k-ε turbulence model was used to predict the flow in the combustion chamber. The results of turbulence kinetic energy, velocity vectors and streamline are presented. The enhancement of air-fuel mixing inside the engine cylinder can be observed, where the design with re-entrance and lower center projection provide better results compared to other combustion geometries designs.

Abstract: Modelling of shockwave propagation in orthotropic materials requires an appropriate description of material behaviour within elastic and plastic regimes. To deal with this issues, a finite strain constitutive model for orthotropic materials was developed within a consistent thermodynamic framework of irreversible process in this paper. The important features of this material model are the multiplicative decomposition of the deformation gradient and a Mandel stress tensor combined with the new stress tensor decomposition generalised for orthotropic materials. The elastic free energy function and the yield function are defined within an invariant theory by means of the introduction of the structural tensors. The plastic behaviour is characterised within the associative plasticity framework using the Hills yield criterion. The complexity was further extended by coupling the formulation with the equation of state (EOS) to control the response of the material to shock loading. This material model which was developed and integrated in the isoclinic configuration provides a unique treatment for elastic and plastic anisotropy. The effects of elastic anisotropy are taken into account through the stress tensor decomposition and plastic anisotropy through yield surface defined in the generalized deviatoric plane perpendicular to the generalised pressure. To test its ability to describe shockwave propagation, the new material model was implemented into the LLNL-DYNA3D code. The results generated by the proposed material model were compared against the experimental Plate Impact test data of Aluminium Alloy 7010. A good agreement between experimental and simulation was obtained for two principal directions of material orthotropy.