Applied Mechanics and Materials Vols. 592-594

Abstract: Despite of the fact that the first and the second generation biomass feedstock are attractive options for the biofuel production, these production schemes are considered unsustainable. As the demand for renewable energy grows exponentially, the practicability of the production of these energy carriers becomes tentative and limited since large arable croplands in tropical and tempe-rate regions are required for their cultivation. Moreover, the conversion processes (i.e. thermo-chemical and bio-chemical) associated with the second generation biomass feedstock are far more complex and sophisticated because of the recalcitrant nature of cellulosic biomass. The biofuels, thus, derived are not cost-competitive with existing petroleum derived fuels. In future, the integra-tion of various biochemical and bioprocessing technologies will be supporting the establishment of biomass energy programs. This paper is an attempt to review the potential of microalgal biodiesel in comparison to the first and the second generation biomass feedstock and its global prospects. Keywords : microalgae biomass, pretreatment, biofuels, clean energy

Abstract: Any aircraft wing is the major component which will play vital role in the generation of lift and at different maneuvering moments throughout the flight. So to maintain this good maneuverability the aircraft wing has to undergo deferent deflections called angle of attack such that the high lift and low drag or vice versa can be settled in the flight. Taking this as the motivation the analysis was carried out on the standard wing airfoil comparing with new designed airfoil. Analyze the numerical simulation values like coefficient of lift, coefficient of Drag, Lift, Drag, and Energy parameters with wind tunnel data to predict accuracy for both the airfoils. Through the selected public literature standard airfoil data and designed airfoil data has been chosen, the geometry was created in the GAMBIT and also the meshing by selecting the suitable c-grid and rectangular grid for the better flow analysis in the FLUENT. The mesh file was imported into the FLUENT software there suitable boundary conditions and operating conditions are given for successful flow convergence. Finally analyzing these results are expecting to be best suitable for good aeromechanical features.

Abstract: A numerical simulation has been carried out to study the effects of twin inclined side mass injection with cross flow through a circular duct using modified model, considering streamline curvature effects by modifying the model constants. 1/7^th turbulent velocity profile has been taken at the inlet. The effects of side mass injection on the flow pattern of the main bulk fluid and the mixing of two mutually cross turbulent flows have been studied in details. The formation of recirculatory flow has been visualized by varying the primary as well as secondary injection angle. With the variation of the injection angle axial velocity profiles at various locations and the centerline velocity variation along the duct have been studied. It has been observed that the impact of primary injection angle variation on the recirculation size is more than the secondary injection angle variation.

Abstract: A comprehensive two dimensional numerical model has been developed to simulate the biomass gasification in a fluidised bed reactor. Gas-solid flows as well as the chemical reactions are considered. Euler-Euler model is adopted to describe the multiphase flow regime inside the reactor. The standard k-є model is used to model the turbulence for each phase. The particle motion inside the reactor is modelled using various drag laws derived from Kinetic Theory of Granular Flow. Biomass fuel after pyrolysis is fed as char and volatile matter. The reaction rates of homogeneous reactions and heterogeneous reactions are determined by Eddy dissipation reaction rate and Arrhenius-Diffusion reaction rate, respectively. Gas velocities, flow patterns, composition of gas product and distribution of reaction rates are obtained. Results are compared with experimental data and found to be in agreement.

Abstract: Diffusing ducts are used in fluid flow systems, mainly in aeroplane engine inlets to decelerate the flow and to correspondingly increase the static pressure. The main problem in achieving a high pressure recovery is the flow separation which results in non-uniform distribution and excessive losses. The present work is aimed to study the flow characteristics in Y-shaped diffusing ducts. The Y-shaped diffuser has rectangular inlets and the outlet is circular with a certain settling length for the flow to be stabilized. The diffuser is modeled in CATIA V5 and further discretized using ICEMCFD12.1. Hexahedral mesh is generated for all diffuser cases, which have been used to capture the hydrodynamic boundary layers. ANSYS CFX 12.1 based on finite volume technique, using k-ε turbulence model is adopted for predicting the flow. The flow field through the 3-dimensional domain is captured by solving the appropriate governing equations namely, the continuity equation and the momentum equation. The convergence criterion is set to 10E-06 for mass and momentum. The whole investigation is done in two phases: in the first phase a commercial CFD code is validated for the results obtained for an S-shaped diffuser and in the second phase the same idea is then extended for the analysis of Y-shaped diffuser. The coefficient of static pressure, cross flow and axial flow velocity distributions are calculated based on the mass averaged quantities for the Y-shaped diffusers (30^o and 40^o).

Abstract: The influence of inlet air temperature on penetration, vaporization and combustion of atomized liquid fuel droplets which is sprayed in a stream of turbulent swirling air flow stream located inside taper can gas turbine combustion chamber has been simulated using the commercial Computational fluid dynamics code star CD. It was observed that the variation of inlet air temperature plays a significant role on penetration, vaporization and combustion. The results were presented with help of plot of average temperature and contour plots of turbulent kinetic energy.

Abstract: The aim of this paper was to present a method to identify the extent of cavitation in pump using the photographic records of cavitation tests conducted on pumps having three different leading edge profiles of the vane. Based on the extent of cavitation in pump, the impeller with circular leading edge was found to be better in operation, followed by plain and ellipse2 leading edge impellers. The technique adapted here was useful to correlate the extent of cavitation with the head drop in pump.

Abstract: The rate of mean blood flow through arteries depend on the resistance to flow presented by the blood vessels. Mean blood pressure decreases as the circulating blood moves away from the heart through arteries and capillaries due to viscous losses of energy. Atherosclerosis is a common phenomenon that is observed causing blockage in coronary arteries leading to cardiac arrest. This blockage is due to the deposition of cholesterol or plaque on the inner walls of the coronary artery. This paper provides an analytical study on the variation of static pressure with multiple blockages in the artery implementing the conventional simulation software. A general three dimensional section of the coronary artery was taken for the analysis and the variation of static pressure with increase in the number of blockages due to cholesterol deposition was studied. Meshing of the geometry and specification of the boundary types have been accomplished using GAMBIT 2.3.16 and the analysis has been carried out using ANSYS FLUENT 6.3.26.

Abstract: Abstract. This paper presents the results of experimental studies of the noise of marine application pump axial flow fan. Axial flow fan is verified by both geometrical and experimental approaches. This section includes grid system used in geometric simulation, and boundary conditions. In order to know the complicate and complex physical features of an axial flow fan, a commercial computational fluid dynamics code, FLUENT, is utilized to perform the flow field analysis, which solves the Navier–Stokes equation using an amorphous finite volume-method. As a commercial computational fluid dynamics code, FLUENT has been extensively used in many turbo machinery applications. In this paper the noise predicted according to geometrical results will be compare with investigational results.

Abstract: A Computational Fluid Dynamics code was developed to study the flow characteristics of two dimensional laminar incompressible flow. Stream function-vorticity formulation was used for solving two dimensional continuity and momentum equations. The unsteady vorticity transport equation is solved by alternate direction implicit scheme. The stream function equation is solved by the successive over relaxation method. A computational code in c-language was developed to solve the tridiagonal system of algebraic equations. Two dimensional flow through a channel with rectangular block at the bottom wall was considered for the validation. The streamline patterns obtained for different Reynolds number shows good agreement with published results. The code was modified to simulate an incompressible laminar wall jet flow around a solid obstacle. Simulations were carried out for different Reynolds numbers. Contour plots of Stream line, u-velocity and v-velocity were obtained. The variations of flow patterns and the development of vortices were studied and reported.