To model and examine the thermal fluid phenomena involved in high-pressure, multi-nozzle spray cooling, a testbed is developed which includes a heating subsystem and an accumulator to pressurize common rail based piezoelectric injectors. Compared to conventional platforms, the implemented testbed allows for an abundance of layout arrangements and settings that provide a greater range of functionality. The volumetric flow rate of the testbed is modeled by a recurrent neural network trained from time-sequential obtained through experiments. The fidelity of the model, as well as the testbed's hardware, software, functionalities, and shortcomings are discussed.

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The aeronautical industry has always strived towards weight-efficient structures since they improve aircraft performance, enable more fuel or payload, reduce cost of manufacturing and operating the aircraft, and reduce the fuel consumption and emissions. Modern airframes are often built in materials with high strength-toweight and stiffness-to-weight ratio, such as aluminium or fibre composites. Fibre composite materials are becoming increasingly common, requiring bolted joints between composite and aluminium parts. Bolted joints are often weak points in the structure, and understanding their mechanical properties in terms of stiffness and strength is of great importance for designing aircraft that are safe to fly.  The aim of the research presented in this licentiate thesis is to improve the understanding of shear-loaded, composite–aluminium, bolted joints in terms of structural compliance, deformation, load distribution, strength and failure, by performing experiments and developing simulation models that describe those experiments.  Experiments are performed where the optical digital image correlation (DIC) technique is used to measure the deformation of the test specimen surface during quasistatic load application until specimen failure. The DIC method enables more detailed deformation measurements compared to traditional methods. Data processing algorithms for noise reduction of DIC measurement data are developed and the results are used in a novel way to detect beginning bearing damage within the material by observing the specimen surface.  The experimental DIC data is used for adapting models, where the goal is to create a structural element that represents a fastener. A structural element is computationally efficient and suitable for implementation in large scale models of airframe structures in an industrial context. A model is proposed and the selection of parameters for this model are investigated. The parameters are identified by fitting to experimental data.  This licentiate thesis is divided into two parts, where the first part gives an introduction and background to the research, while the second part consists of two appended papers. / <p>Further financed by Saab AB</p>

The problem of detection of a constant signal in additive noise is addressed. In centralized detectors all observations are obtained and processed at the same place, whereas in distributed detectors observations on the same phenomenon is obtained at several geographically dispersed local sensors. The local sensors transmit a condensed signal to a global decision maker. In this dissertation we address some problems under both categories. We present centralized truncated sequential nonparametric detectors that can be implemented with a hard-limiter and a dead-zone limiter. These detectors are based on approximations of the sequential sign and the sequential conditional sign detectors. The sequential tests are modelled as Markov chains for design and performance evaluations. By using truncation the possibility of excessively long tests is removed. The approximations allow mathematically tractable design for constant false alarm rate (CFAR) performance. In comparison to the sequential sign and conditional sign detectors, the proposed detectors have slightly higher average sample numbers (ASN) under no signal and nominal signal conditions, but considerably lower ASN for intermediate signal strengths. A number of distributed detection schemes are considered. Firstly, the optimum decision policy for a sequential fusion center with fixed local sensors is studied. The sequential fusion rule is numerically studied using Markov chain modelling. We then focus on deriving optimum M level quantizers at the local sensors where $M > 2$. The solutions are obtained assuming a fixed fusion rule using the Bayesian and the locally optimum detection criteria. The receiver operating characteristics for different values of M and a number of different fusion rules are compared. The performance improves with increasing values of M; however the communication cost also increases. Finally, the concept of multilevel quantization is extended to distributed nonparametric detection. Two schemes are presented which employ Wilcoxon statistics and generate M-level signals from the local sensors. Design issues and numerical performance evaluations of the proposed detectors are presented.

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The lifetime of the high temperature ceramic coating 7 wt.% yttria-stabilized zirconia (7YSZ) is reduced when calcium-magnesium-alumino-silicate (CMAS) particulates enters aero-engines during operation in a sandy or dusty environment, melts, and infiltrates into the coating. 7YSZ undergo both chemical and mechanical degradation from CMAS infiltration during cycling. Characterization methods with synchrotron X-ray diffraction (XRD) provides a non-destructive means to measure the impact of time and temperature on coating degradation with high spatial resolution of 7YSZ coatings infiltrated and annealed by CMAS for 1 hour and 10 hours as well as at 1225 °C and 1250 °C. Additionally, qualitative results of cross-sectional scanning electron microscopy (SEM) allows for the additional observation and validation of the extent of degradation the coatings experience from CMAS infiltration. The XRD measurements show the extent of degradation is more sensitive to temperature around the melting range of CMAS with an increase of approximately 42.8% in the concentration of the monoclinic phases present in the coating at the surface when increasing the annealing temperature from 1225 °C to 1250 °C. It was also found that the degradation was more significant in the first hour of infiltration. There was an increase of 21.5% in the concentration of the monoclinic phases present within the coating at the surface when increasing the annealing time from 1 hour to 10 hours. The results presented within this thesis resolve the impact of time and temperature on the infiltration kinetics of CMAS in coatings which are important considerations in mitigating CMAS infiltration.

This thesis aims to perform a detailed analysis on a 5th Order Polynomial Nozzle, verifying its effectiveness in improving the thrust performance of a Rotating Detonation Rocket Engine. Rotating detonation engines are a promising engine type that uses detonations as a means of combustion rather than traditional conflagration. Through this method, these engines can produce significant amounts of energy while burning less fuel in the process. However, exhaust flow instabilities and swirl limit the engine's potential for use as a means of propulsion. The 5th Order Polynomial Nozzle was previously demonstrated to reduce and control this swirl; however, analysis was limited to side and back-end imaging. Using a recently built thrust stand, direct performance measurements were made with the nozzle being testing in several configurations. Discussed will be the data collected from the thrust stand, side-imaging to confirm flow behaviors similar to previous tests, and future work that is being done to analyze the exhaust flow.

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