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The internal combustion engine (ICE) has been used in automotive vehicles without any significant improvement in energy efficiency for over a hundred years. There are several possibilities for developing a ‘greener’ and more powerful engine such as the homogeneous charge microwave ignition (HCMI) system. In this thesis, the HCMI system is analysed and investigated through simulation based ‘virtual prototyping’ in combination with an intelligent optimisation and a Computer-Automated Design (CAutoD) framework. The intention is to analyse and develop designs which could be used to transform the existing ICE ignition system to the HCMI system with minimal modifications to the existing engine. With the help of the finite element method (FEM), the microwave induced electromagnetic field in the engine cylinder is first simulated for `virtual prototyping' using a computer model. This then takes the prototyping methodology one step further, by replacing the process of human tuning of the prototypes with a computer-automated search process using computational intelligence. To realise this, an interface between the FEM model and the CAutoD framework is designed using the Application Programming Interface (API) of the FEM simulation software. This connection facilitates a rapid exchange of data between the simulation model and the search algorithm. Thus, rendering it possible to accommodate a wider exploration or a higher simulation resolution for superior and more accurate prototyping. Another contribution of this thesis is the improvement of the search performance, including the combination of deterministic and non-deterministic search algorithm as well as using a new technique to solve optimisation problems without using the frequency as an input variable. The knowledge gained from the analysis of nature-inspired algorithms is used to perform a pre-evaluation and hence to provide a population which guides a non-deterministic search towards potentially optimal directions for the global maximum. A CAutoD system is then developed to optimise digital prototyping on various aspects of the ignition device for the HCMI system. This helps deepen the understanding of relationships between the characteristic outputs of a design, and the input parameters that affect the performance of the device. The CAutoD system is first applied to a basic cylinder model, with one single antenna in the middle, to analyse the single variable changes for the antenna designs. It is discovered that the inner antenna length has a significant impact on the maximum electric field intensity inside the engine cylinder. Then it is applied to the design process involving multiple variable changes for the global optimum electromagnetic performance. The results are presented in multi-dimensional graphs, which illustrate the relevant relationships between the different input variables. For example, it is revealed that the resonance frequency is affected more by the piston position than by the antenna length, which underlines the importance of the correct and exact timing advance and control of the ignition event. Subsequent to the extensive and systematic analysis of different antenna designs and input variables, Computer-Automated Design (CAutoD) has been applied to various designs to expand the understanding and virtual prototyping of the HCMI system. The criterion for the best design is to first provide the highest possible electromagnetic propagation performance within the cylindrical cavity by using the lowest microwave input power. With this, the reection of the microwave energy from the cylinder back to the microwave source, under the geometric conditions of the cylinder and antenna model, will also be minimised. During the search process, the default antenna model was extended with an additional antenna, which leads to a dramatic decrease in the field, once the additional antenna is introduced. This determines, that any antenna at the outer shield of the coaxial cable and inside the cylinder head, interferes with the electromagnetic propagation inside the cavity and lowers the propagation performance. The results show that this field will break down the air-fuel mixture inside the cylinder because the field strength is comparable to that, created by a spark plug. Hence, a HCMI system can be designed to replace a spark ignition system without requiring physical modifications to the engine cylinder.

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This thesis presents the research carried out to develop and optimise a novel aerodynamic add-on device for commercial vehicles which would reduce overall fuel consumption without any impact of vehicle aerodynamic stability. A prototype of such a device has been manufactured with existing legal and operational restrictions in view. Additionally, effects of such a device on the rollover stability of a commercial vehicle have been investigated and quantified. This has been done by developing a set of analytical methods to first quantify aerodynamic forces in terms of vehicle shape and flow conditions and then to predict the stability of road vehicles, both using mathematical models formulated using available data.

Electrical power demand in aircraft has grown significantly over the last century, and this trend continues with the More Electric Aircraft (MEA) and All Electric Aircraft (AEA) concepts. Higher voltages such as 270VDC are required to deliver additional power to loads and to optimise aircraft mass. Increased voltages inflict more stress on the Electrical Wiring Interconnect System (EWIS) and increase the impact of series arc faults caused by wiring defects. Solid State Power Controllers (SSPCs) are used to provide fast protection in high voltage distribution systems. The aim of this work is the characterisation, modelling, simulation and detection of series arc faults in 28VDC and 270VDC electrical power distribution systems featuring SSPCs. The majority of passive detection schemes in the literature were designed based on empirical data rather than well characterised electric arc parameters, and thus nuisance trips are unavoidable. To address this series arc faults in 28VDC and 270VDC solid state power distribution systems were characterised using the SAE5692 "Loose terminal" method [8], and it was found that 270VDC arc faults cause a minimal ~5.6% reduction in loop current and load voltage compared with ~54% in 28VDC systems. SSPC output voltage transients caused by series arcs were found to be limited by the presence of SSPC snubbers. Increasing the system loop inductance was found to improve series arc stability resulting in fewer arc quench events. Increasing the capacitive load reduces arc stability and causes arcs to quench more readily thus simplifying detection. These results were later used to experimentally validate a novel series arc fault SPICE model based on the static Nottingham V-I model [9] and wider solid state electrical system model. The arc current and SSPC output voltage results were also used to create a prototype passive series arc fault detection system, which has been demonstrated to SAE5692 under laboratory conditions [8]. A novel multilayer PCB current sensor was developed and experimentally validated for this prototype. To further reduce nuisance trips an innovative active arc fault perturbation scheme was simulated and experimentally demonstrated using SSPC modulation to stimulate and detect arc quench. Another novel complementary series arc fault prevention / confirmation scheme was simulated and experimentally validated using SSPC leakage currents. To minimise nuisance trips due to manufacturing and installation errors a unique Built-In Test (BIT) scheme was also developed and experimentally validated using the SSPC to create artificial current and voltage stimuli.

Direct numerical simulation and wind tunnel experiments have been used to study the effects of free-stream turbulence on axisymmetric wakes. In both cases the wake was introduced to various turbulent streams having various levels of turbulence intensity and length scales. It was found that the presence of the free-stream turbulence changes the wake’s decay rate and does not allow self-similarity to occur (unless maybe very far downstream and way beyond the current measurements reached). Also, the free-stream turbulence was found to be causing a significant transformation in the turbulence structure inside the wake, where the latter was found to be gradually evolving towards the former. Last, the fact that the two approaches were modelling two different problems led to some differences in their results emphasising the importance of the flow structure around the wake generating body in shaping the far wake region.

Brownout is the name given to the degraded visual environment that can develop around a helicopter as it operates in dusty conditions. The dust cloud produced reduces visibility and makes landing the helicopter extremely difficult, there is potential for damage to the aircraft or even loss of life. This thesis works towards understanding the physical processes occurring in the generation of the dust cloud and the application of this understanding in a computational model for dust entrainment. Current brownout simulations use empirical entrainment models originally developed for aeolian sand movement. These models use parameters fitted to experimental evidence, whilst they may recreate the dust conditions of certain scenarios there is need for a physical model that can produce accurate results for prospective aircraft or scenarios. The physical brownout system is a multiphase system made up of particle dynamics of the scales less than a millimetre and fluid scales as large as metres. In this thesis computational modelling of particle systems, fluid systems and multiphase flow systems are used to understand how the rotor wake entrains particles. A model scale 3D unsteady rotor simulation was performed both in and out of ground effect. The flow compares well with experimental results. The ground vortex interaction is quantified. The model scale analysis is complemented by a full scale but steady, 2D, axisymmetric rotor flow analysis. The steady flow is demonstrated to provide sufficient aerodynamic force to lift typically medium sized particles from the ground. The Discrete Element Method is a Lagrangian particle simulation method, in this thesis it is investigated numerically and then the physical behaviour is assessed in a simulation of a probe indentation experiment. The dynamic behaviour matched the experiment well. The Discrete Element Method is recommended as a particle modelling method for a brownout modelling solution. Modelling brownout is extremely difficult due to the range of scales involved. This thesis provides an in depth understanding of the helicopter flow field at small and large scales and the aerodynamic forces and entrainment mechanisms of particles on the ground in the wake of a helicopter.

Engineering design involves the production of large volumes of data. These data are a sophisticated mix of high performance computational and experimental results, and must be managed, shared and distributed across worldwide networks. Given limited storage and networking bandwidth, but rapidly growing rates of data production, effective data management is becoming increasingly critical. Within the context of Airbus, a leading aerospace engineering company, this thesis bridges the gap between academia and industry in the management of engineering data. It explores the high performance computing (HPC) environment used in aerospace engineering design, about which little was previously known, and applies the findings to the specific problem of file system cleaning. The properties of Airbus HPC file systems show many similarities with other environments, such as workstations and academic or public HPC file systems, but there are also some notably unique characteristics. In this research study it was found that Airbusfile system volumes exhibit a greater disk usage by a smaller proportion of files than any other case, and a single file type accounts for 65% of the disk space but less than 1% of the files. The characteristics and retention requirements of this file type formed the basis of a new cleaning tool we have researched and deployed within Airbus that is cognizant of these properties, and yielded disk space savings of 21.1 TB (15.2%) and 37.5 TB (28.2%) over two cleaning studies, and may be able to extend the life of existing storage systems by up to 5.5 years. It was also noted that the financial value of the savings already made exceed the cost of this entire research programme. Furthermore, log files contain information about these key files, and further analysis reveals that direct associations can be made to infer valuable additional metadata about such files. These additional metadata were shown to be available for a significant proportion of the data, and could be used to improve the effectiveness and efficiency of future data management methods even further.

No description available.

This research is concerned with the design of adaptive structures for achieving global multi-shape morphing aerodynamic configurations, by using slender structures. The proposed methodologies pursue two threads towards global optimisation of morphing structures, by providing means of aerodynamic enhancement, using efficient structural shape optimisation. A heuristic approach is proposed in this work that enables morphing through a range of stable cambered airfoils to achieve aerodynamic properties for different manoeuvres, with the benefit of low powered actuation control. This allows large changes in shape by exploiting a range of incremental non-linear structural solutions while keeping prescribed flow characteristics on an aeroelastically stable airfoil. Such an heuristic argument provides basis for global shape control of three-dimensional wings and is applied to aerodynamic design to provide enhanced roll control. A hierarchical strategy is employed, interleaving parameterisation enhancement followed by structural optimisation into the aerodynamic design process, such that the design paradigm, in conjunction with global approximation techniques, is emphasized by enhanced roll while drag is minimised. This figure of merit is complemented by structural metrics and constraints so as to maintain product integrity.