The simulation and flight testing of a light gyroplane aircraft is performed obtaining results regarding the flight dynamics attributes of the vehicle. The main aim of the work was to assess the ability of a mathematical model to simulate rotorcraft in the autorotative flight state. Additionally, the results acquired were to enhance the understanding of an aircraft class for which the existing database of knowledge is limited, particularly with regards to its flight mechanics characteristics. An appropriate aircraft configuration file was obtained enabling a platform of simulation results to be generated. Parametric studies were performed primarily focusing on the influence of the vertical centre of gravity position and rotor speed degree of freedom on gyroplane longitudinal stability. A data acquisition system unique in its sophistication for this class of aircraft was developed and installed on board. The software required to drive the system was designed, and rigorous tests verifying the instrumentation functionality were conducted both on ground and in real flight. A flight test programme capable of fulfilling the experimental aims was devised and realised, yielding results both on the steady state flight characteristics of the aircraft and its dynamic response to pilot inputs. Certain trends were established on the properties of gyroplanes by interpreting the results in terms of basic aerodynamic theory, and by comparing them to previous research findings. A comparison of the experimental data to that obtained from the simulation runs, served to fulfil the model validation aim of the work presented. The effect of model and flight discrepancies on the ability of the mathematical model to realistically emulate flight dynamics in autorotation was discussed, and possible suggestions for the reasons of mismatch were presented.

With test-driven development (TDD) new code is not written until an automated test has failed, and duplications of functions, tests, or simply code fragments are always removed. TDD can lead to a better design and a higher quality of the developed system, but to date it has mainly been applied to the development of traditional software systems such as payroll applications. This thesis describes the novel application of TDD to the development of embedded control systems using an automotive safety system for preventing collisions as an example. The basic prerequisite for test-driven development is the availability of an automated testing framework as tests are executed very often. Such testing frameworks have been developed for nearly all programming languages, but not for the graphical, signal driven language Simulink. Simulink is commonly used in the automotive industry and can be considered as state-of-the-art for the design and development of embedded control systems in the automotive, aerospace and other industries. The thesis therefore introduces a novel automated testing framework for Simulink. This framework forms the basis for the test-driven development process by integrating the analysis, design and testing of embedded control systems into this process. The thesis then shows the application of TDD to a collision prevention system. The system architecture is derived from the requirements of the system and four software components are identified, which represent problems of particular areas for the realisation of control systems, i.e. logical combinations, experimental problems, mathematical algorithms, and control theory. For each of these problems, a concept to systematically derive test cases from the requirements is presented. Moreover two conventional approaches to design the controller are introduced and compared in terms of their stability and performance. The effectiveness of the collision prevention system is assessed in trials on a driving simulator. These trials show that the system leads to a significant reduction of the accident rate for rear-end collisions. In addition, experiments with prototype vehicles on test tracks and field tests are presented to verify the system’s functional requirements within a system testing approach. Finally, the new test-driven development process for embedded control systems is evaluated in comparison to traditional development processes.

The flow around three-dimensional aircraft wings, including delta-wings is very complicated. Much experimental and numerical work has been performed to discover its complexity. To date, all numerical calculations on delta wings have been carried out for either fully laminar or fully turbulent boundary layers. The transition status of the boundary layer is considered unknown despite several efforts to identify transition from laminar to turbulent flow. One such study, called the International Vortex Flow Experiment – 2 (VFE-2), has been carried out by an international group and mainly focuses on the boundary layers on delta wings. The data from the VFE-2 experimentals potentially provide the location of transition on the upper and lower surfaces of the wing to guide associated numerical studies. The effects of Reynolds number, Mach number, angle of attack and the leading edge bluntness are also investigated. Almost all delta wing studies to date have involved tests on wings with sharp leading edges and these have led to the conclusion that the flows are relatively independent of Reynolds number. In fact, most real wings have finite leading edge radii. Hence, the flow separation is no longer fixed at the leading edge, thus making the flow dependent on Reynolds number. This particular aspect has been studied extensively by the VFE-2 team. As part of the VFE-2 project, Glasgow University constructed a delta wing with four different sets of leading edges. Small-, medium- and large-radius edges and a pair of sharp leading edges were constructed in order to compare results from four delta wing configurations. In the current study experiments were carried out on these wings in the 2.65 metre by 2.04 metre, closed circuit, Argyll Wind tunnel of Glasgow University. The models were mounted on a specially designed sting support structure that allowed them to be pitched around a constant centre of rotation throughout the experiments. Tests were conducted at speeds of 20.63 m/s and 41.23 m/s representing Reynolds numbers of 1 x 106 & 2 x 106 respectively, based on the mean aerodynamic chords of the wings. The tests were conducted in three phases. In the first phase, steady and unsteady forces and moments on all wings were measured at an angle of attack that varied from α =100 to 250. The forces and moments were captured at two sampling rates; i.e., 100 Hz and 8000 Hz. The second test series captured flow visualization data on the four wings. In these experiments, a mixture of Ondina oil and paraffin was combined with Dayglo powder and applied to the surfaces of the delta wings. The images of the flow topology on the wings were recorded. The final series of experiments involved Particle Image Velocimetry measurements. A stereo-PIV arrangement was applied in this experiment and two CCD-Cameras were positioned outside the test section for image capture. The current study has identified interesting features of the interrelationship between the conventional leading edge primary vortex and the occurrence and development of the inner vortex on the round-edged delta wings. The inner vortex was first identified and verified by the VFE-2 team. The effects of Reynolds number, angle of attack and leading-edge radii on both vortices are discussed in detail. The steady balance data have shown that the normal force coefficients are sensitive to leading edge bluntness at moderate angles of attack but are less so at high angles of attack. In relation to this, the flow visualization images have also shown that the primary vortex origin is located further aft on the wing at higher leading edge bluntness. This impacts on the strength of the inner vortex which remains a significant flow feature until the primary vortex approaches the apex. The lateral extent of the inner vortex is very dependent on the primary vortex at the leading edge; i.e. the weakening of the primary vortex has positive effects on the inner vortex. Particle Image Velocimetry shows that the increase in leading edge bluntness significantly decreases the swirl magnitude of the primary vortex. The results obtained from the current investigation provide considerable insight into the effects of Reynolds number, angle of attack and bluntness on the flow structures experienced by delta wings, with rounded leading edges. This work will, therefore, inform and guide future investigations of delta wing flows and has the potential to impact on future wing design.

A dynamic inflow model is a powerful tool for predicting the induced velocity distribution over a rotor disc. On account of its closed form and simplicity, the model is highly practical especially for studying flight mechanics and designing control systems for helicopters. However, scant attention has been so far paid to applying this model to analyse autorotative rotors (i.e. rotors in the windmill-brake state), which differ from powered helicopter rotors (i.e. rotors in the normal working state) in that the geometric relation between the inflow and the rotor disc. The principal aim of this research is to theoretically investigate the applicability of existing dynamic inflow models for autorotative rotors, and if necessary, to provide a new dynamic inflow model for autorotative rotors. The contemporary dynamic inflow modelling is reviewed in detail from first principles in this thesis, and this identifies a modification to the mass-flow parameter for autorotative rotors. A qualitative assessment of this change indicates that it is likely to have a negligible impact on the trim state of rotorcraft in autorotation, but a significant effect on the dynamic inflow models in certain flight conditions. In addition, this thesis includes a discussion about the small wake skew angle assumption, which is invariably used in the derivation of Peters and He model. The mathematical validity of the assumption is cast doubt, despite the resultant model has experimentally been fully validated. The author discusses on a theoretical ground the possible reason why the Peters and He model works well in spite of its inconsistent derivation

The interaction of a vortex with a lifting surface occurs in many aerodynamic systems, and can induce significant airloads and radiate impulsive noise. Yet due to their complex nature, the ability to accurately model the important flow physics and noise radiation characteristics of these interactions in realistic situations has remained elusive. This work examines two cases of vortex-lifting surface interactions by enhancing the capabilities of a high fidelity flow solver. This flow solver utilises high spatial discretisation accuracy with a 5th order accurate WENO scheme, and overset meshes to accurately resolve the formation, evolution and interaction of a tip vortex using an inviscid approximation of the fluid. An existing computational infrastructure is further developed and applied to analyse blade-vortex interactions that occur on a helicopter rotor. An idealised interaction is studied, where an independently generated vortex interacts with a rotor. It is found that through the employment of adequate spatial and temporal resolution, the current methodology is capable of resolving the important details of the interaction over a range of vortex-blade miss distances. A careful study of the spatial and temporal resolution requirements is conducted to ensure that the computed results converge to the correct physical solution. It is also demonstrated that a linear acoustic analysis can accurately predict the acoustic energy propagated from these interactions to the far-field, provided the blade surface pressures are accurately computed. The methodology is then used to study an idealised propeller wake-wing interaction, which occur behind a tractor mounted turboprop. A computationally efficient method of modelling the wake-wing interaction is developed and the computed surface pressures of the interaction are confirmed to agree well with the experimental data. The analysis is coupled to an optimisation algorithm to determine a novel wing design, and it is found that significant drag reductions can be achieved with small changes in the twist distribution of the wing. This work confirms that by using a combination of strategies including efficient grids, high order accurate numerical discretisations and a flexible software infrastructure, high fidelity methods can indeed be used to accurately resolve practical cases of vortex-lifting surface interactions in detail while being feasible in a design setting. The airloads and aeroacoustics from these interactions can be accurately predicted, thus confirming that with the modern advances in computing and algorithms, high fidelity methodologies such as those presented in this thesis are in a position to be used to gain a deep understanding of the relevant flow physics and noise radiation patterns, and their impact on aircraft design.

As a rotorcraft descends or manoeuvres, the interactions which occur between the rotor blades and vortical structures within the rotor wake produce highly impulsive loads on the blades and with these a highly intrusive external noise. Brown’s Vorticity Transport Model has been used to investigate the influence of the fidelity of the local blade aerodynamic model on the quality of the prediction of the high-frequency airloads associated with blade-vortex interactions and thus on the accuracy with which the acoustic signature of the aircraft can be predicted. Aerodynamic, wake structure and acoustic predictions using the Vorticity Transport Model are compared against the HART II wind tunnel data for an experimental rotor based on the characteristics of the Bo105 rotor. The model can resolve very accurately the structure of the wake, and allows significant flexibility in the way that the blade loading can be represented. The predictions of two models for the local blade aerodynamics are compared for all three of the HART II flight cases. The first model is a simple lifting-line model and the second is a somewhat more sophisticated lifting-chord model based on unsteady thin aerofoil theory. The predicted positions of the vortex cores agree with measured data to within a fraction of the blade chord, and the strength of the vortices is preserved to well downstream of the rotor, essentially independently of the resolution of the calculation or the blade model used. A marked improvement in accuracy of the predicted high-frequency airloads and acoustic signature of the HART II rotor is obtained when the lifting-chord model for the blade aerodynamics is used instead of the lifting-line type approach. Errors in the amplitude and phase of the loading peaks are reduced and the quality of the prediction is affected to a lesser extent by the computational resolution of the wake. Predictions of the acoustic signature of the rotor are similarly affected, with the lifting-chord model at the highest resolution producing the best representation of the distribution of sound pressure on the ground plane below the rotor.

The aim of the present thesis is to develop new methods that are useful for a space mission analyst to design low thrust trajectories in the preliminary phases of a mission study, where the focus is more on exploring various concepts than on obtaining one optimal transfer. The tools cover three main axes: generating low thrust trajectories from scratch, improving existing low thrust trajectories and exploring large search spaces related to multiple gravity assist transfers. Stress is put on the computational efficiency of the tools. Transfer arcs are generated with shaped based approaches, which have the advantage of having the ability to reproduce close to optimal transfers satisfying time of flight constraints and varied boundary constraints without the need for propagation. This thesis presents a general framework for the development of shape-based approaches to low-thrust trajectory design. A novel shaping method, based on a three-dimensional description of the trajectory in spherical coordinates, is developed within this general framework. Both the exponential sinusoid and the inverse polynomial shaping are demonstrated to be particular two-dimensional cases of the spherical one. The pseudo-equinoctial shaping is revisited within the new framework, and the nonosculating nature of the pseudo-equinoctial elements is analysed. A two-step approach is introduced to solve the time of flight constraint, related to the design of low-thrust arcs with boundary constraints for both spherical and pseudo-equinoctial shaping. The solutions derived from the shaping approach are improved with a feedback linear-quadratic controller and compared against a direct collocation method based on finite elements in time. Theoretical results are given on the validity of the method and a theorem is derived on the criteria of optimality of the results. The shaping approaches and the combination of shaping and linear-quadratic controller are tested on four case studies: a mission to Mars, a mission to asteroid 1989ML, to comet Tempel-1 and to Neptune. The design of low thrust multiple gravity assist trajectories is tackled by an incremental pruning approach. The incremental pruning of reduced search spaces is performed for decoupled pairs of transfer legs, after which regions of the total search space are identified where all acceptable pairs can be linked together. The gravity assists are not powered therefore the trajectory is purely low thrust and the transfer arcs are modelled by shaping functions and improved with the linear quadratic controller. Such an approach can reduce the computational burden of finding a global optimum. Numerical examples are presented for LTMGA transfers from Earth to asteroid Apollo and to Jupiter.

This thesis presents an initial Finite Element (FE) based modelling investigation aimed at supporting the development of 'smart' tyre or intelligent tyre technologies. Physical tests carried out with a stationary (non-rolling) and rolling experimental tyre are used to enhance understanding of tyre behaviour in the contact patch and validate the modelling methodology. Simulation results with the explicit FE package LS-DYNA are then used to characterise the internal stresses and strains at several positions in the tyre tread. Two separate FE models are developed to simulate the stationary and rolling tyre behaviour at the macroscopic level. The models differ only with respect to the mesh density in the circumferential direction, the mesh through the cross section is identical. The complex tyre structure is represented as a rubber and reinforced rubber composite, and the mesh specification and the material descriptions used in the models are discussed. The structural behaviour of the stationary experimental tyre under normal load is simulated. The inflation of the tyre, the wheel fit and the normal loading against the horizontal surface are represented. Simulation results are also presented when a subsequent longitudinal or lateral load is applied to the stationary tyre. These analyses were conducted to determine the longitudinal and lateral tyre stifffiesses, respectively. The predicted normal load-deflection characteristics and contact patch dimensions (length and width) are compared with a reasonable degree of success to those obtained in the full-scale physical tests. The longitudinal and lateral simulations also appear to give realistic tyre stiffnesses. The contact patch dimensions give a good trend-wise agreement, but the length and width are greater than the experimental measurements. A parametric study is carried out and this disparity is related to a deficiency in the performance of the contact algorithms. It is concluded that it not straightforward to accurately predict contact patch behaviour, and therefore the internal transient stresses and strains in a rolling tyre in absolute terms. However, the good trend-wise agreement suggests that the modelling methodology should be capable of predicting internal transient responses which are related to the 'actual' deformations in the contact region. To simulate the rolling tyre behaviour on flat bed and drum surfaces, consideration is given to the inflation of the tyre, the wheel fit, the normal loading and the rotation of the tyre. Numerical instabilities are found to occur and these are related to imperfections inherent in version 950d of the code. This version was, at the time, the most up to date release. The current release is version 960 and it does not contain many of the imperfections in the earlier version. Thus, the flat bed simulation is repeated using the current version. The predicted contact patch stresses are presented and a reasonable correlation is achieved with the experimental data. The internal stresses and strains are then characterised at a number of selected positions in the tread region. These stresses and strains are discussed in context with the development of smart tyre technologies and are useful as a guide to the most appropriate location for an in-tyre sensor (or sensors).

The noise generated by aircraft can be easily heard by those living under the flight path of passenger or cargo carriers. It is considered an environmental pollutant and is treated as such by the International Civil Aviation Organization (ICAO) who monitor and review noise levels. The ICAO imposes substantial fines on those carriers who do not adhere to the decibel limitations. With the new limit or `stage' enforced in 2006, aircraft manufacturers (including jet engine manufacturers) are seeking ways to reduce the noise created by an aircraft. A 1/150th scale model, based on the exit geometry typically found on commercial jet engines, was designed and manufactured at Warwick. The laboratory jet flow conditions operated at 0.7 Mach. The work presented in this thesis looks at the noise generated in a subsonic, co- owing jet, with particular focus given to the distribution sound sources from 5 kHz to 80 kHz (0.375 St to 6.0 St). An acoustic mirror mounted on a motorized 3-way traverse measured radiated sound in the co-flowing jet to produce 2D sound source maps. This is done using combinations of smooth cowl and chevrons for the core and bypass nozzles. For frequencies less than 30 kHz, a reduction of noise was observed using the bypass chevron nozzle compared with the bypass smooth cowl nozzle. Laser Doppler Anemometry (LDA) was used to reveal the 2D flow dynamics of the jet, supporting the acoustic distribution results with velocity profiles of the flow. The change in the flow dynamics with different nozzle combinations is discussed and different regions of the flow were identified.

The control of the noise and vibration generated by an automobile is referred to as Noise, Vibration and Harshness (NVH) engineering. It involves identifying the design detail required to reduce the noise and vibration inside the passenger compartment of the vehicle to levels that are acceptable to the customer. It also involves delivering an engine or a powertrain sound character that is both pleasing to the customer and that suits the character of the vehicle. Tuning the sound generated by a vehicle to deliver a particular character is referred to as Sound Quality Engineering. This document summarizes the work of the EngD research programme that was aimed at developing a structured process for engineering the Powertrain Sound Quality of an automobile. The need for developing a Sound Quality Engineering Process at Jaguar Cars was identified through a review of customer evaluations of the sound in Jaguar's vehicles and those of its competitors. This review established that Jaguar's existing vehicles were trailing the leading competition in terms of the delivery of Powertrain Sound Quality. The reason for this shortfall was that the NVH Department at Jaguar did not have a focus on delivering the customer requirements. Without this focus there was no means of using the customer level requirements, for Sound Quality to drive the vehicle design process. The EngD research programme resulted in the formulation and implementation of a Sound Quality Engineering Process at Jaguar Cars that addressed this need. The first part of the research programme involved developing a means of quantifying the differences in the subjective Sound Quality character perceived by the customer. It was established that the subjective nature of the Powertrain Sound Quality could be represented by two underlying dimensions; a measure of the degree of Refinement and a measure of degree of Powerfulness. An assessment technique was developed that enabled the subjective Sound Quality character for a given vehicle to be quantified through its location within a 2-Dimensional Sound Quality Space, the axes of which were defined by each of the two underlying dimensions of Sound Quality. This 2- Dimensional Sound Quality Space provided the means of quantifying the differences in the Sound Quality characters for all of the vehicles competing in the luxury vehicle sectors. It was applied to define subjective Sound Quality targets for all of the new vehicle programmes at Jaguar Cars. These targets identified the required improvements to each of the two underlying dimensions of Sound Quality needed to address the shortfalls in Jaguar Cars' existing vehicles. The second part of the research programme involved identifying the key acoustic features within the sound signatures of Jaguar's vehicles that were responsible for determining the differences in subjective perception between these vehicles and their competitors. The changes to these key acoustic features were related to the required improvements to each of the two dimensions of Sound Quality that were established from the subjective target setting process. The final part of the research programme involved developing techniques that linked these key acoustic features to the noise sources and paths that were responsible for generating them. Through this link it was possible to establish the changes to these noise sources and paths that were necessary to deliver the required changes to the key acoustic features. In this way the required improvements to each of the two underlying dimensions of Sound Quality were used to define the vehicle design specification at the concept stage of the vehicle development programme and consequently drive the vehicle design process. The ability to link the subjective customer level requirements for Sound Quality to the design detail specification has overcome the previously identified shortfall within the NVH development process at Jaguar Cars. The techniques developed during the EngD research programme were formulated into a Sound Quality Engineering Process. Although the process was developed for Jaguar Cars the findings from the research and the techniques developed have since been applied by the different brands within the Ford Motor Company. Within Jaguar Cars the process has been implemented across all of the new vehicle programmes. It has directly resulted in significantly improved Sound Quality characters in the new vehicles that have been recently introduced to the luxury vehicle market.