Numerical Study on the Influence of Mass and Stiffness Ratios on the Vortex Induced Motion of an Elastically Mounted Cylinder for Harnessing Power

Harnessing the power of vortices shed in the wake of bluff bodies is indeed a boon to society in the face of fuel crisis. This fact serves as an impetus to develop a device called a hydro vortex power generator (HVPG), comprised of an elastically mounted cylinder that is free to oscillate in the cross-flow (CF) direction even in a low velocity flow field. The oscillatory motions in turn can be converted to useful power. This paper addresses the influence of system characteristics viz. stiffness ratio (k*) and mass ratio (m*) on the maximum response amplitude of the elastically mounted cylinder. Computational fluid dynamics (CFD) simulations have been used here to solve a two way fluid–structure interaction (FSI) problem for predicting the trend of variation of the non-dimensional amplitude Y/D with reduced velocity Ur through a series of simulations. Maximum amplitude motions have been attributed to the lowest value of m* with Ur = 8. However, the maximum lift forces correspond to Ur = 4, providing strong design inputs as well as indicating the best operating conditions. The numerical results have been compared with those of field tests in an irrigation canal and have shown reasonable agreement

Mechanical and tribological performance of Al-Fe-SiC-Zr hybrid composites produced through powder metallurgy process

In this work a ternary Al-Fe-SiC metal matrix composites were reinforced using Zr particles through powder metallurgy process. The Al matrix and the reinforcements were mixed in high energy ball mill at a speed of 250 rpm over a period of 5 h so as to develop a homogenously dispersed composite material. The composite powders are then pressed at 500 MPa using hydraulic press. The compressed composite green compacts are then sintered at 500 °C for 2 h and allowed to cool under furnace atmosphere. The densities, micro hardness and compressive strength of Al-Fe-SiC-Zr composites were investigated and reported. The composite materials were characterized using SEM, EDS and XRD. The density of Al-10Fe-10SiC-10Zr hybrid composites was found to be around 3.44 g cm ^−3 . The Zr particles have influenced the micro hardness of the composite materials. The micro hardness of the Al-10Fe-10SiC-10Zr hybrid composites was found to be better compared to Al-10Fe and Al-10Fe-10SiC hybrid composites. The compressive strength of the Al-10Fe-10SiC-10Zr hybrid composites was around 205 MPa which is 44% higher than the Al-10Fe composite material. The porosity of the hybrid composites has reduced when compared to that of Al-10Fe and Al-10Fe-10SiC hybrid composites. The wear studies reveal that Al-10Fe-10SiC-10Zr bear out better wear resistance. The predominant wear mechanism was identified as adhesive wear followed by plastic deformation. This improved wear resistance was due to the formation of oxides layers such Al _2 O _3 , Fe _2 O _3 and also due to the presence of AlFe _3 and Al _3 Zr _4 intermetallics

Stability Derivatives of Various Lighter-than-Air Vehicles: A CFD-Based Comparative Study

An aerostat with a single tether is proposed for the application of wind measurements at low altitudes. In the current study, the aerodynamic model parameters (stability derivatives) of the aerostat are investigated based on a CFD-based approach. The static, as well as the dynamic stability derivatives of the aerostats are presented. The calculation of the dynamic stability derivatives involves the simulation of the oscillations of the aerostats in their axial direction (surge), the vertical direction (heave) and angular motions with respect to the lateral direction (pitch). A forced sinusoidal oscillation is used for the simulation of the aerostat, and one stable period of oscillation is taken for the derivatives’ extraction. Four different aerostats are considered for the current study with four different angles of attack. The Zhiyuan aerostat, HAA aerostat, NPL aerostat and GNVR aerostat are the aerostats considered for this study. The stability derivative results obtained for the four aerostats are analyzed and compared with respect to their geometrical features. From the static aerodynamic characteristics, the Zhiyuan aerostat shows better performance than the other aerostats in terms of the lift–drag ratio. The dynamic stability derivatives of the Zhiyuan aerostat suggest its application as the proposed low-altitude wind measurement system

Commercial aircraft trajectory optimization to reduce flight costs and pollution: metaheuristic algorithms

Aircraft require significant quantities of fuel in order to generate the power required to sustain a flight. Burning this fuel causes the release of polluting particles to the atmosphere and constitutes a direct cost attributed to fuel consumption. The optimization of various aircraft operations in different flight phases such as cruise and descent, as well as terminal area movements, have been identified as a way to reduce fuel requirements, thus reducing pollution. The goal of this chapter is to briefly explain and apply different metaheuristic optimization algorithms to improve the cruise flight phase cost in terms of fuel burn. Another goal is to present an overview of the most popular commercial aircraft models. The algorithms implemented for different optimization strategies are genetic algorithms, the artificial bee colony, and the ant colony algorithm. The fuel burn aircraft model used here is in the form of a Performance Database. A methodology to create this model using a Level D aircraft research flight simulator is briefly explained. Weather plays an important role in flight optimization, and so this work explains a method for incorporating open source weather. The results obtained for the optimization algorithms show that every optimization algorithm was able to reduce the flight consumption, thereby reducing the pollution emissions and contributing to airlines’ profit margins