959 research outputs found

    Dynamics of aircraft antiskid braking systems

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    A computer study was performed to assess the accuracy of three brake pressure-torque mathematical models. The investigation utilized one main gear wheel, brake, and tire assembly of a McDonnell Douglas DC-9 series 10 airplane. The investigation indicates that the performance of aircraft antiskid braking systems is strongly influenced by tire characteristics, dynamic response of the antiskid control valve, and pressure-torque response of the brake. The computer study employed an average torque error criterion to assess the accuracy of the models. The results indicate that a variable nonlinear spring with hysteresis memory function models the pressure-torque response of the brake more accurately than currently used models

    A low power engine test stand

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    The engine test stand is a set of systems needed to identify, map, or optimize an engine. The complex task of the integration of those system requires many areas of expertise. This work tries to tackle that, aiming on three main points. One is provide a list of the set of transducers and measurements needed to test an engine. Second is to provide basic knowledge of the techniques needed to put to practice to achieve a data acquisition. And third the development of a dynamometer controller based on renewable energies, to be more precise, on wind energy harvesting. To conclude this work a transient analysis of the controller is listed.O banco de ensaios de motores alternativos é constituído por um conjunto de sistemas necessários para efetuar identificação, mapeamento ou otimização de um dado motor. A integração dos vários sistemas requer um vasto conjunto disciplinas. Este trabalho, tenta resolver isto, apontando para três pontos importantes do banco de ensaios. Um é listar os vários sensores e medições necessárias para testar um motor. Segundo é prever o conhecimento básico das técnicas necessárias para por em prática um sistema de adquisição de dados. Terceiro é desenvolver um dinamómetro baseado em energias renováveis, mais precisamente, energia eólica. Para concluir este trabalho é efetuada ao controlador uma análise de transição

    Stratified charge rotary aircraft engine technology enablement program

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    The multifuel stratified charge rotary engine is discussed. A single rotor, 0.7L/40 cu in displacement, research rig engine was tested. The research rig engine was designed for operation at high speeds and pressures, combustion chamber peak pressure providing margin for speed and load excursions above the design requirement for a high is advanced aircraft engine. It is indicated that the single rotor research rig engine is capable of meeting the established design requirements of 120 kW, 8,000 RPM, 1,379 KPA BMEP. The research rig engine, when fully developed, will be a valuable tool for investigating, advanced and highly advanced technology components, and provide an understanding of the stratified charge rotary engine combustion process

    Partially Enclosed Vertical Axis Wind Turbine

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    The addition of a partial enclosure across half the front-facing swept area of a Vertical Axis Wind Turbine(VAWT) has been suggested to improve the coefficient of performance, but it undermines the multidirectional functionality. To quantify its potential gains and examine ways to mitigate the losses of unidirectional functionality, a Savonius blade VAWT with an independently rotating enclosure with a passive tail vane control was designed, assembled, and experimentally tested. After experimental testing, it was concluded that this particular enclosure shape drastically reduces the coefficient of performance of a VAWT with Savonius blades. However, the passive tail vane rotated the enclosure to the correct orientation regardless of the wind direction

    Cal Poly Supermileage Electric Vehicle Drivetrain and Motor Control Design

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    The Cal Poly Supermileage Vehicle team is a multidisciplinary club that designs and builds high efficiency vehicles to compete internationally at Shell Eco-Marathon (SEM). Cal Poly Supermileage Club has been competing in the internal combustion engine (ICE) category of the competition since 2007. The club has decided it is time to expand their competition goals and enter their first battery electric prototype vehicle. To this end, a yearlong senior design project was presented to this team of engineers giving us the opportunity to design an electric powertrain with a custom motor controller. This system has been integrated into Ventus, the 2017 Supermileage competition car, bringing it back to life as E-Ventus for future competitions. The scope of this project includes sizing a motor, designing the drivetrain, programing the motor driver, building a custom motor controller, and finally mounting all these components into the chassis. The main considerations in this design are the energy efficiency measured in distance per power used (mi/kWh) and the whole system reliability. Driven train system reliability has been defined as the car starts the first time every time and can complete two competition runs of 6.3 miles each without mechanical or electrical failure. Drivetrain weight target was less than 25 pounds, and the finished system came in at 20 lbs 4 oz. Due to the design difficulties of the custom controller, three iterations were able to be produced by the end of this project, but there will need to be further iterations to complete the controller. Because of these difficulties our sponsor, Will Sirski, and club advisor, Dr. Mello, have agreed that providing the club with a working mechanical powertrain, powertrain data from the club chassis dynamometer using the programmed TI evaluation motor controller board, and providing board layout for the third iteration design for the custom controller satisfy their requirements for this project

    Design of a Novel Concept for Harnessing Tidal Stream Power

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    This project involved the design, manufacture, and testing of a novel water energy harvesting device. Through the use of a bio-mimetic ribbon fin, the device extracted power from flowing water with a competitive efficiency. Intended for use in tidal streams or rivers, this technology is suited for small hydro installations, with the potential for scaling to higher capacity generation

    Development of an Ammonia Reduction After-Treatment Systems for Stoichiometric Natural Gas Engines

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    Three-way catalyst (TWC) equipped stoichiometric natural gas vehicles have proven to be an effective alternative fuel strategy that shows significant low NOx emissions characteristics. However, recent studies have shown the TWC activity to contribute to elevated levels of tailpipe ammonia (NH 3) emissions. Although a non-regulated pollutant, ammonia is a potent pre-cursor to ambient secondary PM formation. Ammonia is an inevitable byproduct of fuel rich operation that results in lowest NOx slip through the TWC after-treatment system.;The main objective of the study is to develop a passive Ammonia Reduction Catalyst (passive-ARC) based NH3 reduction strategy that results in an overall reduction of ammonia as well as NOx emissions. The study investigated the characteristics of Fe-based and Cu-based zeolites SCR catalysts in storage and desorption of ammonia at high exhaust temperature conditions, that are typical of stoichiometric natural gas engines. Continuous measurements of NOx and NH3 before and after the SCR systems were conducted using a Fourier Transform Infrared Spectrometry (FTIR) gas analyzer. Results of the investigation showed that both, the Fe- and Cu zeolite SCRs adsorbed above 90% of TWC generated NH3 emissions below 350--375 °C SCR temperatures. Desorption or slipping of NH3 was observed at exhaust gas temperatures exceeding 400 °C. In terms of NOx conversions, Fe-zeolite showed efficiency between 50--80% above temperatures of 300--350 °C while Cu-zeolite performed well at lower SCR temperature from 250 °C and above with a conversion efficiency of greater than 50%.;In order to efficiently reduce both NOx and NH3 simultaneously over longer durations it was found that an engine-based air fuel ratio operation strategy for the passive-ARC system must be developed. To this extent, the study extended its objectives to develop an engine-based control strategy that results in stoichiometric ammonia production operation followed by brief lean operation to regenerate the saturated ammonia reduction catalyst using high NOx slip through TWC. The study presents comprehensive results of ammonia storage characteristics of SCRs pertaining to stoichiometric natural gas engine exhaust as well as an advanced engine control strategy approach to simultaneously reduce both NOx and NH3 using an alternating air -fuel ratio approach
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