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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

Desenvolvimento de um modelo de mapa de consumo de combustível baseado em aquisição embarcadas. / Development of an internal combustion engine fuel map model based on on-board acquisition.

Steckelberg, Danilo Brito 01 November 2016 (has links)
É apresentada uma metodologia para descrever o mapa de desempenho (ou mapa de consumo de combustível) de um motor de combustão interna como função de suas condições de operação (rotação e torque) baseados em medições embarcadas. É utilizada para este levantamento a combinação de medições via GPS (para a velocidade longitudinal e inclinação de pista) e OBD-II para aquisição de sinais da rede CAN, como rotação do motor e consumo de combustível. É desenvolvida uma metodologia para o cálculo do torque líquido do motor baseado na medição de velocidade e aceleração longitudinal do veículo com uma margem de incerteza de 2% a 5% no cálculo do torque em condições normais de operações. É realizado um detalhamento da origem das incertezas para avaliar a contribuição individual de cada parâmetro. Um modelo de regressão polinomial é utilizado para descrever o mapa de consume de combustível do motor cujos coeficientes característicos são determinados experimentalmente através da metodologia proposta para cinco veículos diferentes a fim de comprovar a eficácia da metodologia. Os coeficientes de correlação variam de 0.797 a 0.997, sendo que em três de cinco veículos o coeficiente de correlação é maior que 0.910, comprovando a robustez da metodologia. / It is presented a methodology to describe the engine performance map (or the engine fuel map) for an internal combustion engine as a function of its operating conditions (engine speed and torque) based on on-board measurements. It is used a combination of GPS measurements for vehicle speed and road grade together with a OBD-II acquisition system in order to acquire information provided by CAN network, such as engine speed and fuel consumption. A methodology to calculate the engine torque based on speed and acceleration measurements is shown with an average uncertainty in the range of 2% to 5% for torque calculation in normal operating conditions. It is presented a detailed breakdown of the contribution of individual parameters in torque calculation uncertainty. A polynomial regression model to describe the engine fuel map is presented and the coefficients for this model is calculated based on on-road measurements for 5 different vehicles to prove the accuracy of the proposed methodology. The correlation coefficients obtained for these measurements are within the range of 0.797 to 0.997 and three out of five vehicles with correlation coefficient higher than 0.910, proving the methodology robust.
12

Teknik med en lärares ögon : En undersökning kring hur lärarna betraktar teknik och ämnets undervisning i årskurs 4-6

Roynezon, Jannica January 2017 (has links)
Sammanfattning Syftet kring undersökningen är att undersöka lärarnas syn och tankar på teknik samt få en uppfattning om hur lärarna undervisar i skolämnet teknik för årskurserna 4-6. Detta görs genom att intervjua lärare som undervisar i ämnet teknik. Intervjuerna görs utefter frågeställningarna: 1. Hur är lärarnas syn och tankar om teknik? 2.Vilka tankar kring undervisningen i teknikämnet har lärare? 3. Vad är lärarnas reflexioner på att teknikämnet får en egen timplan?  Intervjuerna visar att de flesta lärarna som deltagit i undersökningen tycker att det bör finnas en gemensam definition för teknik. Undersökningen visar även att de flesta lärarna tycker att det är bäst att undervisa med teori och praktik varvat men att det är brist på resurser för ämnet teknik som gör det omöjligt att genomföra undervisningen med variationsteorin. / Abstract   The purpose of the study is to investigate the teachers' views and thoughts on technology as well as an understanding of how teachers teach the school subject technology for grades 4-6. This is done by interviewing teachers who teach in the subject of technology. The interviews address the questions: 1. What are the teachers' views and thoughts about technology? 2. What thoughts about teaching in the subject of technology have teachers? 3. What are the teachers’ reflections on the technical subject getting your own timetable? The interviews show that most teachers who participated in the survey find that there should be a common definition of technology. The study also shows that most teachers think it is best to teach theory and practice but that there is a lack of resources for the subject of technology that makes it impossible to complete the theory of variation theory.
13

Desenvolvimento de um modelo de mapa de consumo de combustível baseado em aquisição embarcadas. / Development of an internal combustion engine fuel map model based on on-board acquisition.

Danilo Brito Steckelberg 01 November 2016 (has links)
É apresentada uma metodologia para descrever o mapa de desempenho (ou mapa de consumo de combustível) de um motor de combustão interna como função de suas condições de operação (rotação e torque) baseados em medições embarcadas. É utilizada para este levantamento a combinação de medições via GPS (para a velocidade longitudinal e inclinação de pista) e OBD-II para aquisição de sinais da rede CAN, como rotação do motor e consumo de combustível. É desenvolvida uma metodologia para o cálculo do torque líquido do motor baseado na medição de velocidade e aceleração longitudinal do veículo com uma margem de incerteza de 2% a 5% no cálculo do torque em condições normais de operações. É realizado um detalhamento da origem das incertezas para avaliar a contribuição individual de cada parâmetro. Um modelo de regressão polinomial é utilizado para descrever o mapa de consume de combustível do motor cujos coeficientes característicos são determinados experimentalmente através da metodologia proposta para cinco veículos diferentes a fim de comprovar a eficácia da metodologia. Os coeficientes de correlação variam de 0.797 a 0.997, sendo que em três de cinco veículos o coeficiente de correlação é maior que 0.910, comprovando a robustez da metodologia. / It is presented a methodology to describe the engine performance map (or the engine fuel map) for an internal combustion engine as a function of its operating conditions (engine speed and torque) based on on-board measurements. It is used a combination of GPS measurements for vehicle speed and road grade together with a OBD-II acquisition system in order to acquire information provided by CAN network, such as engine speed and fuel consumption. A methodology to calculate the engine torque based on speed and acceleration measurements is shown with an average uncertainty in the range of 2% to 5% for torque calculation in normal operating conditions. It is presented a detailed breakdown of the contribution of individual parameters in torque calculation uncertainty. A polynomial regression model to describe the engine fuel map is presented and the coefficients for this model is calculated based on on-road measurements for 5 different vehicles to prove the accuracy of the proposed methodology. The correlation coefficients obtained for these measurements are within the range of 0.797 to 0.997 and three out of five vehicles with correlation coefficient higher than 0.910, proving the methodology robust.
14

Performance of Supersonic Turbomachinery for Rotating Detonation Engines

Ford Heston Lynch (14637695) 28 July 2023 (has links)
<p>      Rotating detonation combustion has been investigated since the 1960s and has gained much attention in the past decade due to its promise of pressure gain. In theory, the pressure gain can provide higher power output at inlet total temperatures similar to those of Brayton cycle engines, leading to increased efficiency and decreased engine size. However, complexities presented by detonative combustion have prevented it from becoming widely adopted, especially for turbomachinery applications. A rotating detonation combustor with a transonic or supersonic exhaust imposes rapid fluctuations in pressure, temperature, and flow angle at the inlet of the turbine. To account for these fluctuations, ad hoc turbine designs have been proposed over the last few years, including supersonic bladed and bladeless variants. Computational fluid dynamics simulations have shown that it is possible to extract a meaningful amount of work from these turbines, but dedicated experimental test rigs are needed to validate these designs at relevant conditions in long-duration tests.</p> <p>     Toward this goal, this thesis focuses on three research elements. The first element is the design of a cooled rotating detonation combustor with a downstream turbine that can operate for long durations. The cooled combustor is accomplished in a two-part procedure: (1) repurposing Purdue University’s Turbine-integrated High-pressure Optical Rotating detonation engine (THOR) and (2) designing a lightweight, gaseous film-cooled combustor shroud with ample configurations for pressure, temperature, and optical measurements.</p> <p>     The second element is the design of three supersonic turbines for use in RDEs: an axial-flow bladed turbine, an axial-flow bladeless turbine, and an axial-inflow/radial-outflow bladed turbine. Each turbine is designed for cold flow testing, and provisions for mounting the axial-flow bladed turbine downstream of the cooled combustor are proposed. Supplemental turbine hardware is also designed to provide precise and repeatable conditions for the turbine tests.</p> <p>     The third element is the construction of an energy absorption dynamometer to measure the power output of the different supersonic turbines. Four types of dynamometers are explored, including hydraulic brakes, electromagnetic brakes, electric generator brakes, and airbrakes. Although the literature declares the electromagnetic brake to be more accurate, the most cost-effective solution is to utilize the compressor side of a donated turbocharger. Combining all research elements yields a new test rig for this new class of supersonic turbines.</p>
15

Caractérisation expérimentale d’une turbine de suralimentation automobile et modélisation de ses courbes caractéristiques de fonctionnement / Experimental characterization of an automotive turbocharger turbine and modeling of its performance maps

Salameh, Georges 07 December 2016 (has links)
La diminution de la cylindrée ou le downsizing du moteur est potentiellement l'une des stratégies les plus efficaces pour améliorer la consommation de carburant et diminuer les émissions polluantes. Dans le domaine de la suralimentation, la simulation est limitée par les caractéristiques de fonctionnement des turbines fournies par les constructeurs. Une extrapolation précise et fiable des cartographies turbine est donc l’objectif de cette thèse. Une étude expérimentale sur une turbine radiale d’un turbocompresseur est effectuée avec différentes techniques pour mesurer la cartographie turbine la plus large possible. Les mesures sont effectuées sur un banc turbocompresseur classique avec différentes températures d'entrée turbine. Puis une technique de gavage en entrée et en sortie compresseur est testée. Le compresseur est ensuite remplacé par un autre compresseur à roue inversée qui peut aider la turbine à tourner et même l’entrainer. Les débits les plus faibles et même les débits négatifs sont mesurés. Un banc turbine électromécanique a également été développé, mais n’a pas pu donner de résultats satisfaisants à cause de problèmes techniques mais des évolutions à venir restent prometteuses. Les diverses techniques expérimentales testées ont aussi permis de mesurer le rendement isentropique de la turbine et le rendement mécanique du turbocompresseur. Finalement, plusieurs modèles d’extrapolation des courbes caractéristiques turbine ont été testés et confrontés aux résultats expérimentaux. / Engine downsizing is potentially one of the most effective strategies being explored to improve fuel economy and reduce emissions. In the field of turbocharging,simulation is limited by the operating characteristics of turbines supplied by the manufacturers. An accurate and precise extrapolation of the turbine performance maps is the main aim of this study. An experimental study was done on a radial turbine of a turbocharger with different techniques to measure the wider turbine performance map possible. Measurements were done on a classic turbocharger test bench with different turbine inlet temperatures. Then air was blown to the compressor inlet and exit: it is the compressor “gavage”. The compressor is then replaced with another one with are versed rotor: this compressor can help the turbine turn and even drive it itself. The lowest mass flow rates are measured even the negative ones. An electromechanical turbine test bench was developed but did not work correctly because of technical problems but future developments are promising. The various experimental techniques used allowed also the measurement of the turbine isentropic efficiency and the turbocharger mechanical efficiency. Finally, many extrapolation models of the turbine performance maps were tested and compared to the experimental results.

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