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Le Rim-Rotor Rotary Ramjet Engine (R4E) est un moteur très haute densité de puissance utilisant des statoréacteurs en rotation pour produire un couple à grande vitesse angulaire.Le design structurel d'une première génération de R4E est présenté dans ce mémoire ainsi qu'une validation expérimentale avec combustion haute température. Ces travaux s'imbriquent dans un programme de recherche où l'objectif ultime est de démontrer expérimentalement qu'il est possible de produire de la puissance positive de ce type de moteur. La structure principale du moteur est basée sur l'utilisation d'un Rim-Rotor, un anneau de Carbone-PEEK unidirectionnel, qui reprend partiellement le chargement des propulseurs en compression. Un moyeu en aluminium en une pièce inclut les propulseurs et supporte le système d'allumage inductif intégré à la structure. Ce dernier a été caractérisé indépendamment afin de connaître l'effet des paramètres tels la distance entre les électrodes sur la puissance et l'énergie des étincelles.Le concept final proposé pèse 76 g, ne contient que 5 pièces dans un assemblage unique et peut résister à une vitesse tangentielle de 330 m/s (120 krpm) au niveau des propulseurs lors d'une combustion d'hydrogène de 1 sec. Un autre concept présenté est conçu pour résister 560 m/s (200 krpm) pour des durées de combustion très courtes, sans échauffement significatif des composants. Un modèle structurel analytique est proposé et validé par un modèle numérique ainsi que des essais expérimentaux sans combustion réalisés jusqu'à 188 krpm sans rupture.Le prototype conçu pour la combustion est validé par rapport à ses paramètres de conception et une rupture des pales de turbine survient tel que prédit par le modèle couplé thermique-structurel numérique. Les recherches ont démontré que le concept d'un R4E est viable et qu'il a le potentiel d'atteindre une vitesse tangentielle de près de 1000 m/s en utilisant des matériaux disponibles aujourd'hui. Les dissimilitudes d'expansion thermique entre les composantes, la différence de rigidité entre les pièces de l'assemblage ainsi que le transfert de chaleur vers le Rim-Rotor ont été identifiés comme des considérations importantes pour les futurs concepts de R4E.

Aujourd'hui divers systèmes de propulsion marins existent dont les systèmes de propulsion à jet. De nombreuses études ont été réalisées au cours des vingt dernières années et plus particulièrement par le biais de la simulation numérique ( Computational Fluid Dynamics , ( CFD )). Un modèle numérique simulant l'écoulement au travers un système de propulsion avec une pompe en rotation est développé dans ce projet. Il est également validé avec des résultats expérimentaux obtenus par d'autres chercheurs. Pour se [i.e. ce] faire, différentes étapes sont réalisées. En premier lieu, des paramètres tels que le maillage, le modèle de turbulence ou la modélisation de la rotation du rotor sont validés numériquement sur deux géométries. Le premier cas, bien documenté, correspond à un écoulement au travers une conduite en forme de"S" de section divergente et validé expérimentalement. Le second cas est une pompe où le rotor est en mouvement dans l'écoulement. Un modèle à multiple systèmes de référence ( Multiple Reference Frame,MFR ) est utilisé pour simuler la rotation de la pompe. Les paramètres numériques sont alors fixés pour la suite de l'étude. Ensuite un inodéle numérique d'un système de propulsion à jet d'une motomarine est développé dans un volume de contrôle réduit. Il prend en compte l'ensemble de la géométrie de la propulsion : la pompe en rotation, le venturi et une partie de la coque réelle du véhicule. Les conditions aux frontières sous la coque sont imposées grâce aux données d'une simulation complète du véhicule entier. Ce modèle est validé expérimentalement à deux vitesses (25 mph et 69 mph). Le comportement de l'écoulement est ensuite analysé. Finalement diverses variations géométriques sont effectuées telles que la supression [i.e. suppression] d'appendices dans la conduite ou le déplacement latéral de la lèvre de l'entrée d'eau à divers IVR, Inlet Velocity Ratio (rapport entre la vitesse du véhicule et celle de la pompe). Une augmentation des performances du système est observée à un certain IVR pour une supression [i.e. suppression] d'appendice donnée. La présence d'une plaque permettant le redressement de l'écoulement au niveau de la grille est néfaste à la poussée de même que la présence de l'arbre ou d'ailettes situées à l'entrée de la pompe. Le déplacement de la lèvre a pour objectif de déterminer la position optimale qui permet d'obtenir la meilleure augmentation de performance pour un IVR .

Thesis (MScEng (Mechanical and Mechatronic Engineering))--University of Stellenbosch, 2007. / The focus of this project was to investigate the working of a liquefied gas micro satellite thruster. An introduction is given in which the significance of the project in relation to the literature is stated. The objectives of the project are also stated. In the literature survey the historical development and design specifications of some relevant thruster systems is discussed. An experimental model was designed and built to test the working of a thruster system. Attention is also given to the measurement and calibration techniques used to obtain experimental data. A computer program was written to simulate the thruster system. The experimental set-up was designed so that an accumulator could be charged with liquid butane from a storage tank. The accumulator was charged with 13 ml of liquid butane, which was heated and then exhausted through a nozzle. Copper mesh was placed in the accumulator to improve the heat transfer to the butane vapour before it was exhausted through the nozzle. A cantilever beam was used to measure the thrust of the system. The system was tested under atmospheric conditions of 100 000 Pa as well as under vacuum conditions of 20 Pa. Two nozzles were also tested: nozzle-1 with a throat diameter of 1 mm and an exit diameter of 5 mm and nozzle-2 with a throat diameter of 1 mm and an exit diameter of 1.6 mm. A computer program was written to simulate the flow of the butane vapour through the nozzle, as well as the complex two-phase behaviour of the butane in the accumulator. Traditional gas dynamic theory was used to model the flow through the nozzle. The transient behaviour of the system was modelled to predict the rate of liquid to vapour mass transfer in the accumulator. Additionally, the computer program was developed to simulate the system with copper mesh placed in the accumulator. From the experimental results it was shown that the addition of copper mesh in the accumulator improved the total thrust achieved with a 13 ml charge of liquid butane by more than 50 %. Under atmospheric conditions shockwaves were present in both of the two nozzles tested. Nozzle-2 showed an increase of 91 % in the total thrust achieved over a 5 second burst compared to the total thrust achieved using nozzle-1. With no copper mesh in the accumulator and using nozzle-1 a peak thrust of 39 mN was achieved under atmospheric conditions while under vacuum conditions a peak thrust of 495 mN was achieved. This resulted in a total thrust of 0.365 Ns under atmospheric conditions and 4.88 Ns under vacuum conditions with a 13 ml charge of liquid butane. Using the total thrust achieved the specific impulse of the system was calculated as 5 seconds under atmospheric conditions and 67.5 seconds under vacuum conditions with no mesh in the accumulator and using nozzle-1. The theoretical model compared well with the experimental results except when nozzle-1 was modelled under atmospheric conditions. Under vacuum conditions the results obtained from the theoretical model compared well with the experimental results using both of the nozzles. In the modelling of the mesh in the accumulator an overall heat transfer factor was incorporated into the model to take into account the uncertainty of the heat transfer area as well as the overall heat transfer coefficient. The theoretical model and experimental test results are discussed and thereafter conclusions are also drawn. There are also recommendations made for future work that could be done in the further development of a liquefied gas micro satellite thruster system. It is recommended that a “resistojet” type thruster should be tested at the University of Stellenbosch and that further testing be done with mesh in the accumulator to find the optimum amount of mesh that should be placed in the accumulator.

Thesis (MScEng)--University of Stellenbosch, 2003. / ENGLISH ABSTRACT: The focus of this thesis is on the investigation of the functioning of a liquefied-gas thruster. Such a thruster could be used to provide secondary propulsion to a microsatellite in orbit. A general overview of the need for thrusters in micro-satellites is put forward in the introduction. Motivation for deciding to investigate a liquefied-gas system is presented. Recent developments in the field of micro-satellites are discussed as well as their relevance to the project undertaken. Fundamental background theory relevant to the engineering problems associated with the development and analysis of such a system is also presented. Computer programs were written to simulate such a liquefied-gas thruster system. The experimental work carried out to analyse the system from a practical view-point is documented. Attention is also given to the measurement and calibration techniques used to obtain experimental data. One-dimensional fully explicit transient mathematical models of the thruster system were developed to model the system using both compressed air and butane as propellants. These models were incorporated into computer programs used to simulate the transient behaviour of the system. Although it is intended to use butane as the propellant onboard a satellite, the reason for modelling and simulating a system using compressed air is because air is a convenient fluid to work with from both a theoretical and practical point of view. An experimental model of a thruster system was designed, built and tested using air and butane as propellants. Most of the model was built using perspex to allow for the observation of the two-phase behaviour of the propellant inside the system. Locally purchased components were used for the solenoid and fill valves. Readily available butane lighter fluid was used for butane testing. Self-made heating elements were used to provide heat input to the propellant. Testing was done at different back pressures ranging from 100 kPa down to 20 kPa in a vacuum chamber. Good comparison between theoretical and experimental results was obtained for air. Theoretical results for peak thrusts tended to over predict experimental results by approximately 15 % for a system exhausting to a pressure of 100 kPa. Peak thrusts as high as 0.2 N were obtained for vacuum tests conducted at an absolute pressure of 20 kPa. Peak thrusts of approximately 50 mN were achieved for experimental testing III atmospheric conditions using butane with a starting pressure of between 270 and 290 kPa. Typical average thrusts of between 20 mN and 30 mN were noted for butane testing with initial pressure of between 200 to 300 kPa. Peak thrusts of over 0.1 N were observed for vacuum testing at an absolute pressure of 20 kPa. An equation to correlate the experimentally determined average thrust as a function of pulse duration and starting pressure was developed. This correlated most of the experimental data to within ±25 %. Theoretical results for butane testing are able to predict peak thrusts within approximately 20 % for starting pressures in the range of 200 to 300 kPa. Since the project was an exploratory investigation into a liquefied-gas thruster, some additional aspects relating to such systems were also given attention. The effect of liquid propellant motion or sloshing was considered and recommendations regarding the design and placement of the propellant tanks were made. The use of heat pipes as an alternative to electrical heating elements was investigated and some elementary design aspects are presented graphically. The management of the liquid propellant using surface tension devices was examined qualitatively. Recommendations relating to future projects in the field of simple, low-cost propulsion systems for micro-satellites are put forward. More specifically these recommendations are with regard to: thermo-fluid modelling of the propellant, future experimental work to be done, techniques to measure small thrusts and vacuum chamber testing. / AFRIKAANSE OPSOMMING: Die tesis ondersoek die funksionering van 'n vervloeidegas stuwer. So 'n stuwer kan gebruik word om sekondêre aandrywing aan 'n mikro-satelliet in 'n wentelbaan te verskaf. 'n Algemene oorsig oor die behoeftes van stuwers vir mikro-satelliete word voortgesit in die inleiding. Redes vir die gebruik van 'n vervloeidegas stuwer word bespreek. Onlangse ontwikkelinge in die veld van mikro-satelliet aandrywing word bespreek asook die toepaslikheid daarvan. Fundamentele teoretiese agtergrond verbonde aan die ontwikkeling en analise van so 'n stuwer stelsel word ook gegee. Rekenaarprogramme is geskryf om die gedrag van so 'n stuwer stelsel te simuleer. Eksperimentele werk is gedoen om die stelsel vanuit 'n praktiese oogpunt te analiseer. Aandag word ook gegee aan die metings- en kalibrasietegnieke soos toegepas vir die eksperimentele werk. Eendimensionele volle eksplisiete wiskundige modelle is ontwikkelom die oorgangsgedrag van die stuwer-stelsel te simuleer met beide lug en butaan as dryfmiddel. Hierdie modelle is geïnkorporeer in die rekenaar programme om die stuwer stelsel te simuleer. Alhoewel dit beoog word om butaan as die dryfmiddel aan boord die satelliet te gebruik, is lug ook gebruik vir simulasie weens sy gerieflikheid as 'n vloeier uit beide 'n teoretiese en 'n praktiese oogpunt. 'n Eksperimentele model van die stuwer stelsel is ontwerp, gebou en getoets met beide lug en butaan as dryfmiddels. Die model is hoofsaaklik uit perspex gebou sodat die twee-fase gedrag van die butaan uitgebeeld kon word. Vrylik beskikbare butaan aansteker vloeistof IS gebruik VIr butaan toetsing. Selfvervaardigde verhittingselemente is gebruik om hitte aan die dryfmiddel te verskaf. Toetse is gedoen deur verskeie omgewingsdrukke varieërend van 100 kPa af tot 20 kPa in 'n vakuumtenk te gebruik. Goeie ooreenstemming tussen die teoretiese en eksperimentele resultate vir die toetsing van lug is verkry. Die teoretiese resultate neig om die piek stukrag 15 % hoër te voorspel as die eksperimentele resultate vir 'n stelsel wat tot 'n omgewingsdruk van 100 kPa by die uitlaat. Piek stukragte van meer as 0.2 N is gekry vir vakuum toetse wat gedoen is by 'n omgewingsdruk van 20 kPa. Tydens eksperimentele toetsing met butaan teen 'n aanvanklike druk tussen 270 en 290 kPa, in atmosferiese toestande, is piek stukragte van ongeveer 50 mN behaal. Tipiese gemiddelde stukragte van tussen 20 en 30 mN is waargeneem vir butaan toetsing teen 'n aanvanklike druk tussen 200 en 300 kPa. Piek stukragte van meer as 0.1 N is behaal vir vakuum toetse met 'n absolute druk van 20 kPa. 'n Vergelyking om die gemiddelde stukrag, wat eksperimenteel bepaal is, as 'n funksie van puls tydsduur en aanvanklike druk te korreleer, is ontwikkel. Die meeste eksperimentele data se afwyking van die korrelasie-vergelyking was minder as 25 %. Teoretiese resultate vir butaantoetse het piek stukragte binne 20 % van die eksperimenteel metings korrek voorspel vir aanvanklike drukke tussen 200 tot 300 kPa. Weens die feit dat die projek 'n oorhoofse ondersoek in In vervloeidegas stuwer behels, is aandag ook gegee aan addisionele aspekte wat verband hou met sulke stelsels. Die effek van die vloeistof-dryfmiddel se onstabiele beweging in sy tenke is in ag geneem en voorstelle vir die ontwerp en plasing van die dryfmiddel tenke is gemaak. Die gebruik van hitte pype as 'n alternatief vir elektriese verhittingselemente is ondersoek. Verskeie ontwerp aspekte word grafies voorgestel. Die bestuur van die vloeistof-dryfmiddel deur van oppervlak spannings apparaat gebruik te maak, is kwalitatief ondersoek. Voorstelle vir verdere navorsing in die veld van eenvoudige, lae-koste stuwer stelsels vir mikro-satelliete is gemaak. Meer spesifiek is hierdie voorstelle gerig op die termo-vloeidinamiese modellering van die dryfmiddel, verdere eksperimentele navorsing, tegnieke om klein stukragte te meet en vakuumtenk toetse.

This thesis investigates the impact of upstream duct convolution on the plume development for high speed jets. In particular, investigations are carried out into an unconventional aero-engine exhaust systems comprised of a modified convergent-divergent rectangular nozzle where the converging section of the nozzle includes an S-bend in the duct. The motivation for this work comes from both the military and civilian sectors of the aerospace industry. The growing interest into highly efficient engines in the civilian sector and increasing complexities involved in stealth technologies for military applications has led to new design constraints on aero-engine exhaust systems that require further research into flows through more complex duct geometries. Due to a lack of experimental data into this area in the open literature validation studies are undertaken into flows through an S-bend duct and exhaust plume development from a rectangular convergent-divergent nozzle. The validation work is simulated using RANS CFD with common industrial turbulence models as well as LES with artificial inlet conditions. Subsequently, a CFD investigation into three unconventional aero-engine exhaust systems, with over-expanded conditions, with differing angles of curvature across the converging S-bend is undertaken using both RANS and LES methodologies governed by the validation work. As the curvature of the S-bend was increased it was found that the thrust and effective NPR both decrease. Whilst these changes were within acceptable levels (with some optimisation) for a circumferential extent of up to 53.1 the losses became prohibitive large at extents. For the ducts with a greater circumferential extents separation was seen to occur at the throat of the nozzle; this changes the design parameters of the nozzle leading to a higher Mach number and could potentially be harnessed to improve performance of the engine creating a `variable throat' nozzle. The impact of using different numerical solvers to simulate the flow through an unconventional aero-engine exhaust system has also been considered. The use of LES has shown that the octagonal, hexahedral and trapezoidal shapes initially observed in the development of the plumes of the RANS cases are likely to be an artifact caused by the RANS solver, as would the transverse total pressure gradients observed in the RANS cases at the nozzle exit as they are both absent from all of the LES results. Likewise the implementation of realistic inlet conditions has a significant impact on the development of the plume, particularly in the length of the potential core and the number of shock cells.

Allt eftersom tekniken utvecklas blir elektrisk framdrift ett adekvat alternativ till konventionellt dieselmaskineri, särskilt inom den svenska skärgårdstrafiken eftersom det ofta handlar om korta distanser. En av de allra viktigaste faktorerna vid ett nybygge eller en konvertering av ett fartyg är kostnaden. Den här rapporten belyser de olika utmaningarna som ett mindre skärgårdsrederi möter vid en konvertering till elektrisk framdrivning. Det studien fokuserar på är vilka aspekter man behöver ta hänsyn till vid en konvertering, främst den ekonomiska aspekten och de miljövinster som en konvertering medför. Data har jämförts över hur mycket kostnaderna skiljer sig, för konverteringen och den framtida driften mellan hybriddrift och konventionell drift. Intervjuer har även genomförts med anställda på Koster Marin AB, som varit inblandade i konverteringen till hybriddrift av deras nyinköpta fartyg Kosterbris. Resultatet visar att hybriddrift är ett bättre alternativ än batteridrift för Koster Marin. / With the advance of technology electric propulsion is becoming a plausible alternative to conventional propulsion with diesel engines. Especially for the ferry traffic within the Swedish archipelago, where the conditions often are more favourable to alternatives like battery powered propulsion. One of the most important factors when building a ship or converting an existing one to hybrid propulsion is the cost. This study sheds light on the different challenges a small shipping company could face, when converting a ship. The study primarily focuses on the economic and environmental perspectives. A comparison has been made over the expenses for hybrid- and conventional propulsion, with the conversion and operation in mind. Interviews have also been conducted with employees of Koster Marin AB, who has been involved with the conversion of the company’s recently purchased vessel Kosterbris. The result shows that a hybrid solution is a better option than battery powered operation for Kosterbris.

In order to enable comparison of Helicon ion thruster performance across different vacuum test facilities, an understanding of the effect of operating pressure on plasma plume properties is required. Plasma property measurements are compared for thruster operation at two separate vacuum facility operating pressures to determine the effect of neutral ingestion on Helicon ion thruster operation. The ion energy distribution function (IEDF), electron temperature, ion number density, and plasma potential are measured along the thruster main axis for a replica of the Madison Helicon eXperiment. Plasma property values recorded at the ‘high-pressure condition’ (3.0×10^(-4) Torr corrected for argon) are compared to values recorded at the ‘low-pressure condition’ (1.2×10^(-5) Torr corrected for argon) for thruster operation at 100 - 500 watts radio frequency forward power, 340 – 700 gauss source region magnetic field strength, and 1.3 - 60 sccm argon volumetric flow rate (0.039-1.782 mg/s). Differences in plasma behavior at the ‘high-pressure condition’ result from two primary neutral-plume interactions: collisions between accelerated beam ions and ingested neutrals leading to a reduction of ion energy and neutral ionization downstream of the thruster exit due to electron-neutral collisions. Electron temperature at higher operating pressures is lowered due to an electron cooling effect resulting from repeated collisions with neutral atoms. Results suggest that Helicon ion thruster plasma properties are greatly influenced when subjected to neutral ingestion.

International Telemetering Conference Proceedings / October 23-26, 2000 / Town & Country Hotel and Conference Center, San Diego, California / The National Aeronautics and Space Administration’s (NASA) Marshall Space Flight Center (MSFC) in Huntsville, Alabama will launch the Propulsive Small Expendable Deployer System (ProSEDS) space experiment in late 2000. ProSEDS will demonstrate the use of an electrodynamic tether propulsion system and will utilize a conducting wire tether to generate limited spacecraft power. This paper will provide an overview of the ProSEDS mission and will discuss the design, and test of the spacecraft telemetry system. The ProSEDS telemetry subsystem employs a combination of Commercial Off-The-Shelf (COTS) hardware and launch vehicle telemetry system components to minimize costs as well as power consumption. Several measures were used to aid the conservation of spacecraft power resources. First, the transmitter was modified to limit input power consumption to less that 20 watts while providing approximately two watts Radio Frequency (RF) output power. Secondly, the ProSEDS on board Global Positioning System (GPS) receiver is being used to control input power to the transmitter in order to limit the telemetry operations to occasions when the spacecraft is in proximity to preprogrammed ground station locations.

Following a spinal cord injury (SCI), participation in regular exercise can enhance physical capacity and performance in activities of daily living. With this in mind, the use of subjective ratings of perceived exertion (RPE) may provide an easy-to-administer alternative to traditional methods of regulating exercise intensity (e.g. heart rate and power output (PO)). A physically active lifestyle is also associated with a reduced risk of cardiovascular disease, in part because exercise exerts anti-inflammatory effects. Examining the plasma response of inflammation-mediating chemical messengers, known as cytokines, to traditional and novel exercise modalities may help maximise the anti-inflammatory potential of regular exercise. Participants with a cervical level SCI successfully self-regulated a 20 min bout of moderate intensity wheelchair propulsion (Chapter three). No differences in physiological or PO responses were observed during the imposed-intensity and self-regulated wheelchair propulsion in the trained population group. In a non-SCI group of novice wheelchair-users, a differentiated RPE specific to the exercising muscle mass (RPEP) was the dominant perceptual signal during submaximal wheelchair propulsion (Chapter four). The novice group successfully self-regulated a 12 min bout of moderate intensity wheelchair propulsion, comprising of a discontinuous 3 x 4 min protocol, using differentiated RPEP. In contrast, a more accurate self-regulation of light intensity wheelchair propulsion was observed when employing traditional overall RPE compared to RPEP. Following strenuous wheelchair propulsion, plasma concentrations of the inflammation-mediating cytokine interleukin-6 (IL-6) were significantly elevated in non-SCI and thoracic level SCI participants (Chapter five). Impaired sympathetic nervous system (SNS) function was associated with a reduced IL-6 response in participants with a cervical level SCI. The plasma IL-6 response to 30 min moderate intensity (60% VO2peak) arm-crank ergometry (ACE) was associated with an elevation in the anti-inflammatory cytokine IL-1 receptor antagonist (IL-1ra) independent of SNS activation (Chapter six). Light intensity ACE resulted in a small, significant plasma IL-6 response but no IL-1ra response. The addition of functional electrical stimulation-evoked lower-limb cycling to concurrent hand cycling, termed hybrid exercise, resulted in a greater plasma IL-6 response compared to moderate intensity hand cycling alone in participants with a thoracic level SCI (Chapter seven).