<p>A series of experimental tests were performed to study the transient response of gas/liquid injectors exposed to transverse detonation waves. A total of four acrylic injectors were tested to compare the response between gas/liquid and liquid only injectors, as well as compare the role of various geometric features of the notional injector design. Detonation waves are produced through the combustion of ethylene and oxygen, at conditions to produce average wave pressures between 128 and 199 psi. The injectors utilize water and nitrogen to simulate the injection of liquid and gaseous propellants respectively. Quantification of injector refill times was possible through the use of a high-speed camera recording at a frame rate of 460,000 frames per second. High frequency pressure measurements in both the gaseous and liquid manifolds allow for quantification of the temporal pressure response of the injectors. Variations in simulant mass flow rates, measured through the use of sonic nozzles and cavitating venturis, produce pressure drops up to 262 psi across the injector. Injector refill times are found to be a strong function of the impulse delivered across the injector. Manifold acoustics were found to play a large role in injector response as manifolds that promote manifold over-pressurizations during the injector recovery period recover quicker than designs that limit this response.</p>

While paraffin has the potential to be a high performance fuel for hybrid rockets, sloughing-off of portions of the fuel during the burn, fuel-liner delamination during fabrication, difficult ignition, and the escape of significant amounts of unburned paraffin droplets from the combustion chamber have hindered efforts to demonstrate superior performance in paraffinueled hybrid motors. This work investigates several methods for enhancing the performance of paraffin-based hybrid motors including the use of anti-sloughing baffles in the grain liner, ignition media to ensure repeatable and prompt engine start, improved methods for fuel grain production, and aluminum and potassium nitrate additives. The results of the tests demonstrate modest improvements in anti-sloughing and total impulse, compared to the baseline paraffin fuel grain. Difficulty achieving sufficiently repeatable results with the available commercial motor prevented some of the research goals from being completed but lead to a better understanding of the factors affecting the performance space.

No description available.

This thesis examines the growth of the space elevator community in America from 1975 to 2010. It argues that the continued practical failures of the space elevator, a proposed technology for efficiently transporting payloads and people into space without conventional propulsion sources, resulted from a technological paradigm built around the rocket and supported by a traditional engineering culture. After its triumph in landing men on the Moon from 1969 to 1972, the United States' National Aeronautics and Space Administration (NASA) sought to advance novel concepts for further space exploration, but it fumbled in pursuing nontraditional notions of escaping the atmosphere such as the space elevator. Employing interviews with space elevator advocates Bradley Edwards and Michael Laine and other primary and secondary sources, this thesis also draws on concepts such as technological paradigms, engineering cultures, and the technological sublime. It concludes by demonstrating how success eluded the marginalized space elevator researchers who found themselves grappling with the vast social and technical system that supported the rocket's hegemony. / Master of Arts / This thesis examines the growth of the space elevator community in America from 1975 to 2010. It argues that the continued practical failures of the space elevator, a proposed technology for efficiently transporting payloads and people into space without conventional propulsion sources, resulted from a technological paradigm built around the rocket and supported by a traditional engineering culture. The technological paradigm of the rocket encompassed all of the people and practices that made the rocket work. After its triumph in landing men on the Moon from 1969 to 1972, the United States' National Aeronautics and Space Administration (NASA) sought to advance novel concepts for further space exploration, but it fumbled in pursuing nontraditional notions of escaping the atmosphere such as the space elevator. Much of this failure is owed to an engineering culture within NASA that looked down upon challenging the rocket. This thesis demonstrates how success eluded the marginalized space elevator researchers who found themselves grappling with the vast social and technical system that supported the rocket's hegemony.

Medan normen i tidsserieklassificering (TSC) har varit att förbättra noggrannheten, har nya modeller med fokus på effektivitet nyligen fått uppmärksamhet. I synnerhet modeller som kallas ROCKET"(RandOm Convolutional KErnel Transform), som fungerar genom att slumpmässigt generera ett stort antal kärnor som används som funktionsextraktorer för att träna en enkel åsklassificerare, kan prestera lika bra som andra toppmoderna algoritmer, samtidigt som de har en betydande ökning i effektivitet. Även om ROCKET-modeller ursprungligen designades för Univariate Time Series (UTS), som definieras av en enda kanal eller sekvens, har dessa klassificerare också visat utmärkta resultat när de testats på Multivariate Time Series (MTS), där egenskaperna för tidsserien är spridda över flera kanaler. Därför är det av vetenskapligt intresse att utforska dessa modeller för att bedöma deras övergripande prestanda och om effektiviteten kan förbättras ytterligare. Nyligen genomförda studier presenterar en ny algoritm som kallas Sequential Feature Detachment (SFD) som, förutom ROCKET, avsevärt kan minska storleken på modellerna samtidigt som noggrannheten ökar något genom en sekventiell funktionsvalsteknik. Trots dessa anmärkningsvärda resultat var experimenten som ledde till slutsatserna begränsade till användningen av UTS, vilket lämnade utrymme för utforskningen av denna algoritm på MTS. Följaktligen undersöker denna studie hur man kan utnyttja ROCKET-algoritmer och SFD för att förbättra MTS-klassificeringsuppgifter vad gäller både effektivitet och noggrannhet, samtidigt som god tolkningsbarhet bibehålls som en begränsning. För att uppnå detta genomförs experiment på flera University of East Anglia (UEA) MTS-datauppsättningar, testar modellensembler, grupperar kanaler baserat på förutsägbarhet och undersöker kanalrelevanser tillsammans med SFD. Resultaten visar hur modellanpassning inte är en metod som kan öka noggrannheten i testuppsättningarna och hur förutsägbarheten för enskilda kanaler inte bibehålls längs datapartitioner. Det visas dock hur användning av SFD med MiniROCKET, en variant av ROCKET som inkluderar slumpmässiga kanalkombinationer, inte bara förbättrar klassificeringsresultaten, utan också ger ett statistiskt signifikant kanalrelevansmått. / While the norm in Time Series Classification (TSC) has been to improve accuracy, new models focusing on efficiency have recently been attracting attention. In particular, models known as ”ROCKET” (RandOm Convolutional KErnel Transform), which work by randomly generating a large number of kernels used as feature extractors to train a simple ridge classifier, can yield results as good as other state-of-the-art algorithms while presenting a significant increase in efficiency. Although ROCKET models were originally designed for Univariate Time Series (UTS), which are defined by a single channel or sequence, these classifiers have also shown excellent results when tested on Multivariate Time Series (MTS), where the characteristics of the time series are spread across multiple channels. Therefore, it is of scientific interest to explore these models to assess their overall performance and whether efficiency can be further improved. Recent studies present a novel algorithm named Sequential Feature Detachment (SFD) which, on top of ROCKET, can significantly reduce the model size while slightly increasing accuracy through a sequential feature selection technique. Despite these remarkable results, the experiments leading to the conclusions were limited to the use of UTS, leaving room for the exploration of this algorithm on MTS. Consequently, this thesis evaluates different strategies to implement ROCKET and SFD algorithms for MTS classification tasks, focusing not only on improving efficiency and accuracy, but also on adding interpretability to the classifier. To achieve this, experiments were conducted by testing model ensembles, grouping channels based on predictability, and examining channel relevances alongside SFD. The University of East Anglia (UEA) MTS archive was used to evaluate the resulting models, as it is common with TSC algorithms. The results demonstrate that model ensembling does not increase accuracy in the test sets and that the predictability of individual channels is not maintained across dataset splits. However, the study shows that using SFD with MiniROCKET, a variant of ROCKET that includes random channel combinations, not only can improve classification results but also provide a statistically significant channel relevance measure.

Rocket propulsion using the hybrid-propellant scheme is a technology that offers much promise in applications where high-performance liquid rocket engines are deemed too complex and solid rocket motors are considered to lack performance or safety. However, despite extensive research, there is still a lack of knowledge in the theoretical aspects of hybrid rocketry, especially in the area of fuel-oxidizer mixing and fuel regression rate. This lack of a good theoretical model makes the implementation of good, practical solutions and mature, well-functioning designs more diffcult. This disadvantages the hybrid rocket engine when compared to liquid rocket engines or solid rocket motors.In this study, a hybrid rocket engine burning polymethyl methacrylate (PMMA) with compressed air has been designed to the point of a preliminary design defnition. PMMA is a transparent material, and this has been utilized to create a transparent-chamber rocket engine where engine processes can be studied with various optical methods withoutinterrupting or disturbing the operation of the engine. The function of hybrid rocket engines, the technological solutions involved in designing working hybrid rocket engines and the constituent parts of hybrid rocket engines have been studied. The nature of the trade-offs between performance and simplicity that occur when designing a rocket engine are also studied, with a focus on maximizing simplicity, safety and minimizing expenses, while still designing an engine that fulfills basic requirements. The results include a design defnition with a preliminary user’s guide, a feasibility study, and a summary of the results of the hybrid rocket performance model that was used to determine appropriate design parameters.

<p dir="ltr">Improving launch vehicle and satellite propulsion system performance directly correlates to the delivery of more mass (or quantity) on orbit from launch vehicles, longer duration satellite missions, and longer ranges for missiles/interceptors. Alternative propulsion devices such as rotating detonation engines (RDEs) offer the potential for significant performance gains but their operability has only been demonstrated on “battle hardened” laboratory devices for rocket applications. The objective of this research was to demonstrate cooling and structural approaches that mature rotating detonation rocket engines (RDREs) to flight like maturation levels.</p><p dir="ltr">Multiple 1.6”/4.1 cm diameter RDE combustors were designed, fabricated, and tested. The RDE tested the most accumulated 309 seconds of hot fire testing and 118 starts/shutdowns. Long duration testing was completed to characterize heat flux and high cycle fatigue (HCF) loading. Large quantities of short duration tests were completed to evaluate thermal cycling impacts to the combustor structure and evaluate low cycle fatigue (LCF) loading. The hardware experienced 118 LCF loadings on the combustor cooling passages, equivalent to the amount of thermal cycle starts and shutdowns. An endurance test was completed at 60 seconds in duration, demonstrating operation well beyond thermal steady state. Additionally, ~3.7 million HCF loadings were placed on the combustor cooling passages, equivalent to the approximate amount of detonation wave passes present for all of the WC 2.0 testing.</p><p dir="ltr">Predicted operating pressures ranged from 5 to 15 atm. The highest-pressure conditions resulted in hot gas wall temperatures exceeding 1000°F on the outerbody of the combustor and injector face temperatures peaking at 350°F. Water calorimetry was used to compute heat fluxes, which were then compared to traditional rocket engine throat level heat fluxes calculated using Bartz equations under average operating conditions. The outerbody heat fluxes reached up to 3.7 kW/cm², while injector face heat fluxes reached a maximum of 1.6 kW/cm². When compared to Bartz throat level values, the outer-body heat fluxes varied from 0.9 to 1.6 times the throat level values, and injector heat fluxes ranged from 0.3 to 0.5 times the throat level values.</p><p dir="ltr">A combined thermal and pressure loading fatigue assessment was completed that took into consideration mean stresses and cumulative damage from the spectrum of loading events. Traditional rocket combustor life is typically limited by the thermal cycles that can be placed on the cooling channel hot wall. The fatigue analysis results highlight the reduction in available low cycle fatigue life as RDE's experience larger thermal loads when compared to traditional rocket combustors. Low cycle fatigue life will become especially challenging in higher chamber pressure combustors where thermal environments are more extreme, and the ability keep hot wall temperatures within acceptable levels is more challenging.</p><p dir="ltr">The study also highlights that the passing detonation wave provides a high cycle fatigue (HCF) failure mechanism that is not present in traditional rocket combustors. This failure mechanism is the result of the pressure pulse provided by the passing detonation wave causing a variable load on the hot wall. This variable load is applied at frequencies commonly in the 10's of kHz, resulting in large quantities of loading cycles when operated at rocket like durations (>60 sec). This HCF failure mechanism is most impactful at larger chamber pressures where the detonation pressure ratio causes peak pressures to be elevated, resulting in larger cyclic stresses and strains in the hot wall. The results indicate that high chamber pressure combustors may experience HCF life exceedances within seconds of operation.</p>

No description available.

Two mathematical models (a one and a three-dimensional) were adopted to study, numerically, the thermal hydrodynamic behavior of flow inside a single cooling channel of a Nuclear Thermal Rocket (NTR) engine. The first model assumes the flow in the cooling channel to be one-dimensional, unsteady, compressible, turbulent, and subsonic. The working fluid (GH2) is assumed to be compressible. The governing equations of the 1-D model are discretized using a second order accurate finite difference scheme. Also, a commercial CFD code is used to study the same problem. Numerical experiments, using both codes, simulated the flow and heat transfer in a cooling channel of the reactor. The steady state predictions of both models were compared to the existing experimental results and it is concluded that both models successfully predict the steady state fluid temperature distribution in the NTR cooling channel.

In this thesis, combustion processes in a laboratory-scale methane based low pressure rocket motor (LPRM) is studied experimentally and numerically. Experiments are conducted to measure flame temperatures and chamber temperature and pressure. Single reaction-four species reacting flow of gaseous methane and gaseous oxygen in the combustion chamber is also simulated numerically using a commercial CFD solver based on 2-D, steady-state, viscous, turbulent and compressible flow assumptions. LPRM geometry is simplified to several configurations, i.e. Channel and Combustion Chamber with Nozzle and FWD. Flow in a Bunsen burner is simulated inside Channel geometry in order to validate the reaction model. Grid independence study is also conducted for reacting as well as non-reacting flows. Numerical model is calibrated based on experimental results. Results of the computational model are found in a good agreement with the experimental data after calibrating specific heats of the products. Parametric study is conducted in order to investigate the effects of different mass flow rates and chamber pressures on flow and combustion characteristics of a LPRM to provide insight to future studies.