Characterization and improvement of a hybrid chemical rocket

The concerning project addresses a theoretical and practical analysis of an improved small hybrid rocket prototype. The main characteristics of the motor are: a fuel-oxidizer combination consisting of a hollow cylinder of PMMA and pure oxygen injected at high pressure (3-4 bar), and a pure convergent nozzle for which several values of the throat diameter were be tested. The main goal of the project was to characterize the rocket performance. In order to do so, first it was necessary to perform some physical improvements such as the inclusion of a pressure transducer for the estimation of the oxygen flow rate, as well as the redesign of the supporting structure and the amelioration of the data acquisition system for the obtaining of meaningful thrust readings. Moreover, a theoretical one-dimensional model was develop to contrast the empirical data and ensure its validity. Finally, three parametric studies were performed for which several experiments with different combinations of nozzle throat diameter, fuel cartridge length and oxygen tank pressure setting were carried out. The relevance of this project is significant given that this was the first phase of this prototype in which meaningful results were obtained. From the experimental phase, it was possible to conclude that the oper-ation of the device was highly transient and that the feeding oxygen orifice did not reach sonic conditions during operation against the expectations. Additionally, the correlation between the theoretical model and the empirical data showed an acceptable fitting, and although the lack of chamber temperature measure-ment was an inconvenient, it was possible to estimate the said parameter from the previous results. Finally, with respect to the parametric studies, it was concluded that: the low oxygen pressure ultimately caused that the reduction of the fuel cartridge length had no effect on the rocket performance; the largest nozzle (6mm throat diameter) coincided with the critical pressure ratio, and consequently, the smallest nozzle (4mm throat diameter) was clearly choked, although the increase in the rocket thrust was not very significant; the increase of the tank pressure was the most efficient way to increase the performance of the motor. Ultimately, it was concluded that a considerably higher thrust force could be achieved by performing future physical improvements to the deviceIngeniería Aeroespacia

Langley aerospace test highlights, 1985

The role of the Langley Research Center is to perform basic and applied research necessary for the advancement of aeronautics and space flight, to generate new and advanced concepts for the accomplishment of related national goals, and to provide research advice, technological support, and assistance to other NASA installations, other government agencies, and industry. Significant tests which were performed during calendar year 1985 in Langley test facilities, are highlighted. Both the broad range of the research and technology activities at the Langley Research Center and the contributions of this work toward maintaining United States leadership in aeronautics and space research, are illustrated. Other highlights of Langley research and technology for 1985 are described in Research and Technology-1985 Annual Report of the Langley Research Center

Estudio teórico-experimental de compresores de pistón herméticos con diferentes refrigerantes

[EN] This thesis is included within the objectives of the project of the Ministerio de Ciencia yTecnologia DICORE.Within the frame of this project, the thesis is focused in the study of hermetic piston compressors for refrigeration systems to attend their adaptation and use with new refrigerants. Firstlyaseriesoffivereciprocatingcompressorsofdifferentcapacitieslubricated with POE working with propane and R407C were analyzed. Since traditionally the compressors working with propane have being lubricated with mineral oil of high viscosity, an additionally a comparative study between a MO of high viscosity and the used POE were developed to evaluate the possible convenience of using POE of lower viscosity with propane. These tests included a compressor characterization with both oils, OCR measurement (Oil Circulation Rate) and finally thedesignofaproceduretomeasuretheoilexpelledbythecompressorinthestartup. Once verified the reliability in the experimental level of propane as refrigerant with this compressors. A general semi-empirical compressor model which allows on the one hand to analyze from a theoretical point of view the observed differences between both refrigerants and on the other hand to asses the design of compressors working with other refrigerants. The obtained model allows obtaining an estimation of the volumetric efficiency and the compressor when the refrigerant with an error lower than 3% in most of the tested working conditions. Finally, the development of the model has pointed out the possibility of the existence of an effect of condensation of the refrigerant during the compression process. Thiseffectthathabituallyisnotcontemplatedinthemodelsofthebibliographywould allow to explain the discrepancy between the dead volume of the compressor considered by the manufacturer and the obtained dead volume with the model.[ES] La presente tesis se encuentra englobada dentro de los objetivos del proyecto del Ministerio de Ciencia y Tecnología DICORE. En este contexto este trabajo se centra en el estudio de compresores de pistón herméticos para sistemas de refrigeración con el fin de asistir a su adaptación y uso con nuevos refrigerantes. Inicialmente se procedió a analizar una serie de cinco compresores de pistón de distintas capacidades lubricados con POE funcionando con propano y con R407C, observando a nivel experimental las diferencias observadas en su comportamiento. Puesto que tradicionalmente los compresores que han utilizado propano han venido siendo lubricados con aceite mineral de viscosidad alta, se realizó adicionalmente un estudio comparativo entre aceite MO clavus GV 68 y POE ISO 32 con el fin de determinar la posible aparición de algún problema relacionado con la lubricación y el aceite POE de menor viscosidad. En estas pruebas se procedió a caracterizar un compresor funcionando con ambos tipos de aceite, a realizar medida de OCR (Oil Circulation Rate) y por último se diseño un procedimiento de medida del aceite expulsado por el compresor en el arranque. Una vez comprobada la viabilidad a nivel experimental del propano como refrigerante en este tipo de compresores se procedió a realizar un modelo semiempírico general de compresor que permitiese por un lado analizar desde un punto de vista teórico las diferencias de funcionamiento de ambos refrigerantes. Dicho modelo permitiríaasíasistiraldiseñodecompresoresfuncionandoconotrosrefrigerantes. El modeloasíobtenidoproporcionaobtenerunaestimacióndelrendimientovolumétrico y del compresor cuando se sustituye el refrigerante con un error inferior al 3% en la mayoría de las condiciones de trabajo evaluadas. Porúltimo,eldesarrollodelmodelohaapuntadolaposibilidaddelaexistenciade una condensación de parte del fluido frigorígeno durante el proceso de compresión. Dicho efecto que no es habitualmente contemplado en los modelos de la bibliografía permitiríaexplicarladiscrepanciaentreelvolumenmuertoestimadoporelfabricante del compresor y el volumen muerto obtenido con el modelo.[CA] La present tesi es troba englobada dins dels objectius del projecte del Ministeri de Ciència i Tecnologia DICORE. Dins d’aquest context este trevall es centra en l’estudidecompressorsdepistóhermèticsperasistemesderefrigeracióperaassistir a la seua adaptació i ús amb nous refrigerants. Primerament es va procedir a analitzar una sèrie de cinc compressors de pistó de distintescapacitatslubricatsambPOEfuncionantambpropàiambR407C,observant a nivell d’experimental les diferències observades en el seu comportament. Ja que tradicionalment els compressors que han utilitzat propà han vingut sent lubricats amb oli mineral de viscositat alta, es realitze addicionalment un estudi comparatiu d’estos dos olis a fi depoder establir l’existència d’algun problema relacionat amb la lubricació i l’oli POE de menor viscositat. En estes proves es va procedir a caracteritzar un compressor funcionant amb estos dos tipus d’oli, a realitzar mesura d’OCR (Oil Circulation Rate) i finalment se disseny un procediment de mesura de l’oli expulsat pel compressor en l’arrancada. Una vegada comprovada la viabilitat a nivell experimental del propà com a refrigerant es va procedir a realitzar un model semi-empiric general de compressor que permetera d’una banda analitzar des d’un punt de vista teòric les diferències de funcionament d’estos dos refrigerants permetent així assistir al disseny de compressors funcionant amb altres refrigerants. El model així obtingut permet obtindre una estimació del rendiment volumètric i del compressor quan se substituïx el refrigeren-te amb un error inferior al 3% en la majoria de les condicions de treball avaluades. Finalment, el desenrotllament del model ha apuntat la possibilitat de l’existència d’una condensació de part del fluid frigorigen durant el procés de compressió. Dit efecte que no és habitualment contemplat en els models de la bibliografia permetria explicar la discrepància entre el volum mort estimat pel fabricant del compressor i el volum mort obtingut amb el model.Dar gracias también al Ministerio de Educación y Ciencia que concediéndome la beca FPI asociada al proyecto DICORE me proporcionó el apoyo económico suficiente para poder realizar esta tesis.Navarro Peris, E. (2006). Estudio teórico-experimental de compresores de pistón herméticos con diferentes refrigerantes [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/135957TESI

Application of ultrasound in twin-screw extrusion and microinjection molding: improvements of properties of processed materials and nanocomposites : polymers and biopolymers

Pla de Doctorat Industrial, Generalitat de Catalunya, Aplicat embargament fins el dia 22 de novembre de 2022The plastics industry is in constant evolution looking to improve the properties of new materials and performance in different applications. Currently, the environmental impact associated with the use of plastics is one of the main concerns for the society. It was reflected in regulations at European level such as SUP Directive, Green Deal or studies such as Patents for tomorrow's plastics by European Patent Office on the trends reflected in research on alternative materials to conventional plastic. In order to transfer these new and more sustainable alternatives to an industrial and realistic environment, first applied research has to be carried out on both the development and processes of the materials to optimize their performance. In this thesis study, applied research was carried out using ultrasound technology on different nanocomposites and their transformation processes. Advances in the application of ultrasound for different transformation processes have been studied previously to ensure the approach of the practical study. This study focuses on the application of ultrasound in the process of obtaining new formulations by compounding extrusion and in injection molding, specifically in microinjection. The application of nanotechnology in the development of new materials will allow an improvement in performance and will open a range of new possibilities and applications. To explore the potential of ultrasonic molding (USM) technology, a preliminary process stability study was performed with polypropylene. The evaluation was carried out from a mechanical point of view, in which it was shown that, with an optimization of the process parameters and a correct design approach of the components with the nodal point allow a stability close to production was allowed. To deepen into the potential of USM technology in synergy with new nanocomposite formulations, a comparative study with the conventional microinjection process was performed. Two different nanocomposites based on a biopolymer matrix of poly 3-hydroxybutyrate with Cloisite 20 (organic modification), and with Cloisite 116 (unmodified) were studied. This research reveals that the USM technology, is stable obtaining micro-pieces, maintaining the chemical structure of the initial biocomposite without degrading and homogeneously achieving an exfoliation of both nanoclays. Conventional microinjection did show slight changes in the level of degradation and chemical structure, highlighting that it was not possible to micro-mold samples of the material with the unmodified nanoclay. The stabilization of the compounding extrusion assisted by an ultrasound system has been studied, with a design of a single component that allows the new approach to work in continuous condition and on pre-industrial equipment. Due to the success of the new component, it was possible to carry out the study of new formulations of polypropylene loaded with two different nanoclays (Cloisite 20 and Garamite 1958) and glass bubbles. The new nanocomposites reached the mechanical properties of a conventional material used for door panels in the automotive sector, but with a reduced density. The aim was to demonstrate that it is possible to reduce the weight of plastic components used in the automotive industry and reduce CO2 emissions for a standard vehicle. The research carried out in this thesis work has opened a new field of application to nanocomposites for weight reduction with improved mechanical properties when high level of dispersion is reached. In addition, the potential of USM technology for micro-molding applications has been demonstrated, showing high stability without material degradation during the process, and good dispersion of nano-reinforcements.El sector del plástico está en continuo cambio en busca de mejorar sus propiedades y rendimiento en diferentes aplicaciones. Actualmente. el impacto ambiental asociado al uso de los plásticos es una de las principales preocupaciones en el ámbito social. Se puede ver reflejado en regulaciones a nivel europeo como SUP Directive. Green Deal o estudios como el que efectúa la Oficina de Patentes Europeas Patents for tomorrow's plastics sobre las tendencias que reflejan las investigaciones en materiales alternativos al plástico convencional. Para poder llevar a un ambiente industrial y realista estas nuevas alternativas más sostenibles. primero se ha de llevar a cabo una investigación aplicada tanto del desarrollo de los materiales como de los procesos que pueden optimizar su rendimiento. En este estudio de tesis se lleva a cabo una investigación aplicada sobre diferentes nanocompuestos y sus procesos de transformación que pueden ser mejorados con la tecnología de ultrasonidos. Se ha estudiado los avances en la aplicación de ultrasonidos para diferentes procesos de transformación con el objetivo de enfocar correctamente el estudio práctico. Este estudio centra la aplicación de los ultrasonidos en el proceso de obtención de nuevas formulaciones por extrusión compounding y en el moldeo por inyección, concretamente en microinyeccion. La aplicación de nanotecnología en el desarrollo de nuevos materiales permitirá una mejora del rendimiento y abrirá un abanico de nuevas posibilidades y aplicaciones. Para explorar el potencial de la tecnología de microinyección por ultrasonidos (USM}, se realizó un estudio preliminar de estabilidad del proceso con un polipropileno. La evaluación fue llevada a cabo desde un punto de vista mecánico, en el que se demostró que con una optimización de los parámetros de proceso y un enfoque de diseño correcto de los componentes que hacen intervenir el punto nodal, se puede alcanzar un nivel de estabilidad cercano a producción. Para profundizar en el potencial de la tecnología USM en sinergia con nuevas formulaciones de nanocompuestos, se realizó un estudio comparativo con el proceso de microinyección convencional. Dos nanocompuestos basados en una matriz del biopolímero poli 3-hidroxibutirato con Cloisite 20 (modificación orgánica). Y con Cloisite 116 (sin modificar) fueron estudiados. Este estudio revela que la tecnología USM además de ser estable en la obtención de micropiezas, mantiene la estructura química del biocompuesto inicial sin llegar a degradación y alcanzando homogéneamente la exfoliación de ambas nanoarcillas. La microinyección convencional si mostro ligeros cambios a nivel de degradación y estructura química, destacando que no fue posible micromoldear muestras del material con la nanoarcilla sin modificar. La estabilización del proceso de extrusión compounding asistida por ultrasonidos ha sido estudiado, diseñando un componente único que permite al sistema de ultrasonidos trabajar en régimen continuo en equipos preindustriales. Gracias al éxito del nuevo componente, se ha podido llevar a cabo el estudio de nuevas formulaciones de polipropileno argado con dos nanoarcillas diferentes (Cloisite 20 y Garamite 1958) y esferas huecas. Los nuevos nanocompuestos alcanzaron las propiedades mecánicas de un material empleado para paneles de puerta en el sector automoción, pero con una densidad reducida. El objetivo fue demostrar que se puede reducir el peso de los componentes plásticos empleados en automoción y reducir las emisiones de CO2 para un vehículo estándar. La investigación llevada a cabo en este trabajo de tesis ha permitido abrir un nuevo campo de aplicación a los nanocompuestos para reducción de densidad con buenas propiedades mecánicas cuando la dispersión es alta. Además, se ha demostrado el potencial de la tecnología USM para aplicaciones de micromoldeo, mostrando alta estabilidad sin degradación del material durante el proceso, y buena dispersión de los nano-refuerzos.Polímers i biopolímer

STIRLOCHARGER POWERED BY EXHAUST HEAT FOR HIGH EFFICIENCY COMBUSTION AND ELECTRIC GENERATION

Stirling engines have been in existence since the early 1900s, and have been of little study in the recent years. Stirling engines are low power, heat engines which work on the principle of a temperature differential between the hot and cold sides. This thesis will look into the integration of a Stirling engine onto a turbocompressor for automotive applications calling the device a Stirlocharger

On the use of hydrogen peroxide in ignition systems bioinspiration from the bombardier beetle

A novel ignition system was studied experimentally, in which small volumes of hydrogen peroxide -of the order of pl/s- were injected at the immediate site of ignition, during the firing of a focus discharge igniter (FDI). Initially, the new ignition system was evaluated at an atmospheric expansion rig in the Mechanical Engineering of Leeds University. Afterwards, experiments were undertaken in an atmospheric testing facility with an industrial Rolls-Royce Olympus combustion chamber using kerosene Jet-A1 as the fuel and atmospheric air as the oxidizer. The study concentrated on the determination of the lean ignition limits o f the kerosene-air mixture at various air mass flow rates with and without the addition of H20 2. Notable improvements, from 6.5% to 44%, in the ignition limits of the fuel-air mixture were attainable by using only a maximum amount o f 10.8pl/s o f H20 2 during only the ignition process. The study suggests that these improvements are directly related to the increase in the ignition efficiency of the ignitor, by radical enhancement through the injection of the H20 2 plasma medium. Comparisons were made, between a fuel atomiser that was in normal service and of the same device but washed, in order to test the igniter’s ability to initiate combustion under poor and high fuel spray qualities (FSQ). The results indicate an enhanced improvement in the ignitability limits during poor air-fuel mixing quality when using the H20 2 as described above. A biodiesel fuel was also selected to test the effect that the new ignitor system has in a low-volatility fuel. The question of how to create the small amounts of hydrogen peroxide that will be used for ignition was also approached. An idea of producing the required H20 2 came by studying the bombardier’s beetle unique mechanism which produces H20 2 for defending itself from predators. Simulation work using Chemkin was conducted to investigate the production o f H20 2 by passing hydrocarbon fuels through a catalyst. When passing propane-air through a platinum/ rhodium catalyst the simulations show that H20 2 production is possible in rates enough to supply the proposed novel ignition system. A more specialised study in the chemistry of the production of H20 2, from gas-turbine fuels, is suggested. A cost effective method o f an onsite H20 2 production in small amounts would be an ideal topic for further study

The NASA Scientific and Technical Information System: Its scope and coverage

Subjects of scientific and technical documents considered for inclusion in NASA's information bank are broadly summarized under the various categories used in Scientific and Technical Aerospace Reports and International Aerospace Abstracts. A general definition of each category is followed by a list of the aspects of each subject which are of exhaustive, selective, or negative interest because of their relevance to aerospace science and technology and to other NASA projects

Lentokoneen ympäristöjärjestelmän mallipohjainen vikadiagnostiikka

An environmental control system (ECS) creates habitable living conditions inside an aircraft by pressurizing the cabin, controlling temperature and providing breathing air. This has a major impact on a crew’s comfort, performance and safety. The objective of this thesis was to develop a simulation model of an aircraft’s ECS and use it to acquire more knowledge of the ECS’s dynamic response. Another area of interest was how modifications affect ECS performance. The project also included comprehensive measurements in order to verify the simulation model. The thesis resulted in a partially verified simulation model which is valid in some of the most common flight situations. The model still needs further development and thorough testing to increase simulation accuracy and validity. Especially accurate implementation of the dynamic response needs further investigation and research. Despite an unfinished model, we were able to gather new knowledge of the ECS and its characteristics