Gerardo Carbajal

Building international experiences into an engineering curriculum – a design project-based approach

This paper is a descriptive account of how short-term international and multicultural experiences can be integrated into early design experiences in an aerospace engineering curriculum. Such approaches are considered as important not only in fostering a students interest in the engineering curriculum, but also exposing them to a multicultural setting that they are likely to encounter in their professional careers. In the broader sense, this programme is described as a model that can be duplicated in other engineering disciplines as a first-year experience. In this study, undergraduate students from Rensselaer Polytechnic Institute (RPI) and Universidad del Turabo (UT) in Puerto Rico collaborated on a substantial design project consisting of designing, fabricating, and flight-testing radio-controlled model aircraft as a capstone experience in a semester-long course on Fundamentals of Flight. The two-week long experience in Puerto Rico was organised into academic and cultural components designed with the following objectives: (i) to integrate students in a multicultural team-based academic and social environment, (ii) to practise team-building skills and develop students’ critical thinking and analytical skills, and finally (iii) to excite students about their engineering major through practical applications of aeronautics and help them decide if it is a right fit for them.

Micro-Rotational Generator

Energy harvesting is a relatively new research area that extracts energy from the surroundings to power autonomous systems. This project presents a generator that harnesses the motion of high speed rotational motors for machine health monitoring. Wireless accelerometer-based sensors for detecting crack initiation on rotating shafts are typically limited by the battery finite lifetime. Miniature generators attached to rotating shafts can scavenge small amounts of energy for powering such monitoring systems. Electromagnetic induction approaches (using coils and magnets) have been widely described in literature for larger machines but few at the micro-scale. This paper investigates a multiple-pole permanent magnet design with multiple-stacks of planar coils for energy generation without using Silicon-based processing at the micro-scale. Planar coils are manufactured from 18μm thick Copper-clad on 25μm thick polyimide. The 25mm diameter coils were stacked and bonded with cyanoacrylate for a stacked thickness of 360μm. The rotor was made of a 25mm in diameter (2mm thick) CNC machined PMMA disk with 20 slots (1mm×2mm×6mm) for placing commercial NdFeB permanent magnets. The entire generator had a volume smaller than 1.5cm3 . Experimental results show that the generator is capable of producing an average voltage output of 15.5V and 727mW of power (with a matching load) at a constant rotational speed of 29,500rpm.Copyright

Preliminary Cost Assessment for Offshore Wind Energy in Puerto Rico

The high cost of energy in Puerto Rico (e.g.,

Flow Around an Autonomous Underwater Vehicle With Bio-Inspired Coating

0.27/kWh in September 2014) due to its dependence on fossil fuels (i.e., 61% of electricity production) has become a direct burden on individuals and a critical barrier on economic development in the Island. To alleviate the cost of energy and reduce environmental pollution and greenhouse effects, the Puerto Rico Electric Power Authority (PREPA) is seeking to establish over 380 MW of electrical power from wind sources as part of its renewable energy portfolio. However, contrary to a wind energy study that indicates that the greatest potential for wind power extraction in Puerto Rico resides offshore, all PREPA’s wind energy projects are onshore. This investigation considers a preliminary assessment for the use of offshore wind energy in the eastern region of Puerto Rico. A theoretical model was used to calculate the wind power and levelized cost of energy (LCOE) for three typical offshore wind turbines with nominal output power of 2,300 kW, 3,000 kW, and a 3,600 kW. The results suggest that a smaller wind turbine will be more cost effective in the offshore region of Puerto Rico. As shown in the results, the LCOE could be as low as

Experimental Study of Deicing Process in an Airfoil Application

0.20/kWh for the 2,300 kW turbine and as high as

Design, Analysis and Simulation of an Intake Manifold

0.36/kWh for the 3,600 kW turbine. Keywords— Image Compression, ANN, HIS energy, wind, offshore, cost, Puerto Rico. Digital Object Identifier (DOI): http://dx.doi.org/10.18687/LACCEI2015.1.1.186 ISBN: 13 978-0-9822896-8-6 ISSN: 2414-6668

A Quantitative Analysis of Kinetic Energy Harvesting for Hybrid Power Supplies

Flow separation is a major factor in the form drag experienced by a moving object. In particular, suppressing or reducing flow separation is critical in the reduction of energy expenditure of autonomous underwater vehicles. Previous research suggests that bio-inspired micro-fibrillar structures are capable of reducing the boundary layer separation in a turbulent flow. Here, we present laboratory measurements using particle tracking velocimetry near the wall of two submersible vessel models: one coated with an array of micro-fibers and a second one with smooth walls. The flow around the vessels was enticed by the ordered micro-fibers to retain higher velocities near the wall of the vessel. The experiments suggest that separation of the flow may be reduced by the use of the bio-inspired micro-fibers. Keywords—Bio-inspired, Drag reduction, Flow Separation,

Experimental Study of an Airfoil Heat Pipe Subjected to an Impingement of Hot Gases

A customized airfoil for deicing process was designed, built and tested in order to investigate the effect of icing on the airfoil and the process of removing it by heating processed. A numerical simulation was performed to provide more details of the fluid flow characteristics of the presence of the ice and the temperature distribution on the airfoil when it reached the steady state conditions. An experimental setup was developed to measure and record the transient temperature response on the trailing and leading edge respectively. The experimental results suggest that from a minimum temperature of −10°C on the trailing edge, and 0°C in the leading edge with ice on the surface, the time to reach the steady state temperature of 46°C in the leading edge and 38°C in the trailing edge was close to 8 minutes approximately.Copyright

Analysis of Water Production of a 1.2 KW PEM Fuel Cell

A complete intake manifold was designed and built for a 600cc engine. This device was part of the engine’s air admission system for use in a formula type racecar for an engineering competition. The effect of the plenum volume, plenum shape, inlet restrictor geometry, and runner length, and how these affect the intake manifold performance was numerically investigated. A CFD based FEA software, Ricardo WAVE, was used to model the engine parameters and intake geometries, and perform running engine simulations to evaluate the intake manifold’s performance. Different acoustic geometries were generated, tested and simulated with Ricardo WAVE via parametric iterations. The intake manifold’s performance capacity was tested; torque and horsepower curves were measured under controlled operating conditions in a dynamometer and compared with Ricardo WAVE results. It was found an acceptable agreement between the numerical and experimental data.© 2013 ASME

Experimental Analysis of the Nusselt Number for Jet Impingement on a Flat Plate

This study presents a quantitative analysis of experimental data for extracting energy from human body motion and its possibility of powering portable electronic devices, such as consumer electronics or biomedical monitoring sensors. Since portable electronic devices are typically limited by the size and lifespan of batteries, energy harvesting shows potential as alternative for extending battery life. The acceleration was collected experimentally from 10 subjects while walking and running at different velocities on a treadmill. The acceleration results were studied and a figure of merit consisting of the acceleration-squared-to-frequency was found to determine, in addition to the quality factor, as the important factors for optimal energy harvesting. It was determined that from average walking an energy harvester can produce a power output density greater than 1mW/cm3.Copyright