Search

Can Battery Electric Vehicles replace conventional internal combustion engine vehicles for commuting purposes when exposed to a busy corporate activity within the city of Edinburgh? This thesis investigates the application of Battery Electric Vehicles (BEV) use in a commercial business environment in the city of Edinburgh, Scotland UK. The motivation behind this work is to determine if the Battery Electric Vehicle can replace conventional fossil fuel vehicles under real world drive cycles and the desire by many to combat the causes of climate change. Due to the nature of this work a significant part of the work will be underpinned by the quantitative methodology approach to the research. As the question indicates the research is supported by real live data coming from the vehicle both in proprietary data logging as well as reading and analysing the data coming from the vehicles own Electronic Control Unit (ECU).There will be mixed research methodology encompassing quantitative and qualitative research to obtain a complete response in respect to the management of the vehicle these methodologies will be the analysis of the measurable data as well as explorative, to gain the underlying reasons and motivations for choosing a battery electric vehicle as an option to the conventional vehicle for this type of application use.

Composite materials are finding increasing utilisation in a number of transportation industries concerned with making structures lighter to reduce environmental impact and improve efficiency. Nevertheless, composite structures are susceptible to damage from low-velocity impact events leading to a significant reduction in compression- after-impact residual strength. Another major challenge is to ensure a prescribed level of crashworthiness of fibre-reinforced composite vehicles. The accurate assessment of the effect of impact damage and the performance of structures under crush loading for composite aerostructures, for example, currently requires costly and highly inefficient experimental testing to meet certification requirements. The aim of this project is to develop and validate a reliable, predictive material damage model for capturing impact damage, residual strength and energy absorption capacity of thermoset and thermoplastic composites for crashworthiness assessments. A mesoscale intralaminar damage model, which combines a range of novel techniques to accurately capture the material response under damaging loads, was developed. This physically-based model makes a significant contribution to composite modelling capability by accounting for the intralaminar nonlinear material response, unloading/reloading and load reversal behaviour, fibre-dominated and matrix-dominated damage mode interactions and robust characteristic length calculation. A cohesive zone model, with mixed-mode softening law, was used to model the interlaminar damage. The presented model requires only physically measureable parameters, such as geometry, ply-level material properties and loading conditions, to achieve an accurate predictive solution of impact and crush behaviour of composite structures. A series of tests have been conducted for the measurement of interlaminar and intralaminar fracture toughness as well as the non-linear shear behaviour of AS4/PEKK thermoplastic composite laminates. The measured intrinsic ply-level values were then used as input material parameters for the finite element analysis. The effectiveness of the composite damage model was validated using experimental data obtained from in-house experimental testing as well as from the literature. Results showed that the model can accurately predict the intralaminar damage features, delamination damage area of composite structures under low-velocity impact as well as compressive behaviour and residual strength in compression after impact. Both the qualitative and quantitative aspects of intralaminar and interlaminar damage for wedge-shape and corrugated-shaped composite structures under crush loading were accurately captured. The predicted crush morphologies, force displacement response and dissipated energy were in a good agreement with experimental results, which demonstrates the reliability of this model in predicting impact and crush response of composite structures. The proposed model can be exploited by industry to reduce time and cost in the development of composite structures.

Human technological advancement has continually created new opportunities for machinery to automate intensive tasks. However, these machines still need to be delivered and often controlled by humans. Autonomous Ground Vehicles (AGVs) can completely remove the locomotion dependency of these systems on humans, enabling a robotic revolution. The locomotive performance of AGVs is dependent on the quantity and quality of information received about the terrain ahead; for this purpose, vision is by far the most effective sense. Contextual machine vision is a new area of research where fundamental questions such as how to optimise a visual system specification for a locomotive platform to enable fast locomotion are yet to be addressed. In this thesis, abstract mathematical models of a generic vision sensor and generic locomotor platform were developed to investigate the relationship between sensor specification and locomotor performance with respect to a single key parameter, the maximum ground speed. Initially a static AGV model was investigated, before being expanded to include forward motion, thus enabling the maximum dynamic performance of an AGV to be evaluated. The vision sensor model was designed with interchangeable sensor geometries so that the performance of multiple sensor geometries could be compared. Two of the sensor geometries were designed to approximate a digital camera and human eye, while the third removed non-linearities associated with the detector. The optimum specification to enable maximum speed was defined by the geometry of the sensor. The achievable proximity to the optimum is restricted by system resolution. Generally the sensor geometries analogous to a digital camera and human eye outperformed the linearised model, however, this model can be made insensitive to sensor angle which can be advantageous. Optical flow algorithm performance was not directly effected by detector geometry. Although the resolution variation of the non-linearised detectors and locomotion context reduced tracking performance. Simulating pose error on the model with a random or systemic error resulted in the outcome that vision was a requirement for motion estimation, leading to the development of an AGV vision system for human AGVs. The performance of a visually limited, controlled, human AGV, in a virtual reality environment showed a minimum of 500 features was required for good performance at a foot placement task.

Pipeline robots, borehole robots or exploring robots that work in underground environments can be classified as underground robots. When an underground robot takes a task, tracing and mapping the track of the robot is very important. This project addresses the development of a positioning technique for stepwise underground robots, which have been developed in Durham University. This research is expected to provide a general benefit to stepwise robotic positioning systems rather than a particular robotic or other situation. The initial period of this project was the most difficult. After a few months of literature searching, no suitable positioning technique had been found. Existing techniques are suitable for surface robots, undersea robots or airborne robots but are far away from the application requirements for underground robots. Positioning technology depends on sensor techniques and measurement technologies. The underground environment restricts the use of absolute measurement technologies. Consequently, underground robotic positioning systems heavily rely on relative measurements, which can cause unbounded accumulation of the positioning errors. Moreover, underground environments restrict the use of many high precision sensors because of restricted space and other factors. Hence, the feasibility of developing high, long-term, accuracy underground robotic positioning systems was problematic. Since it was found that there was a lack of research on underground robotic positioning, fundamental investigation became necessary. The fundamentals include the dominant error and the characters of the accumulation of positioning errors. After the investigation of the fundamentals the difficulty and feasibility of developing a high long-term accuracy positioning system was understood more clearly and the key factors to improve the accuracy of a positioning system were known. Based on these, a novel parallel linkage mechanism based approach was proposed. This approach has flexibility in terms of geometrical structure and provides the possibility to improve long-term accuracy of a positioning system. Although parallel linkage mechanisms have drawn a great deal of attention from researchers in passed years, this is the first time a parallel linkage mechanism has been applied to a robotic positioning system. Consequently, new problems were generated by this application of parallel linkage mechanisms. In this project, a Principal Component Analysis (PCA) method is applied to solve the positioning problems and a particular case has been used to show how to solve these problems. Through this case, the advantages of this approach and the feasibility to improve the positioning accuracy is presented. The methodology that can be used to solve the problems for different particular cases can also be used to carry out study for general situations, which have also been illustrated. Many problems still need to be solved. At the end of this thesis, some further problems are discussed. The author of this thesis believes that the proposed approach can be applied to industrial projects in the near future.

An analytical approach for satellite orbit determination methodology will be investigated in this work. The motivation for this study is the realisation that enhanced microsatellites can be expected which require accurate orbital knowledge and control onboard to support their payloads. However, a satellite tracking capability has not yet been implemented at Surrey even on the ground segment, as this would involve a considerable cost to maintain and operate. Advanced modern technology enables micro or nanosatellites to have low cost and low power Global Positioning System (GPS) receivers, which opens the way for onboard orbit determination. However, the heavy computational demand required for executing orbit determination has made such an approach unsuitable given the onboard processing environment. In order to overcome this problem, a novel analytical description of a perturbed orbit has been developed by focusing on near circular orbits which is appropriate for Low Earth Orbit (LEO) satellites. To use this analytic description of the orbit for orbit determination extensively reduces the computational demand as no numerical integrator is required to propagate the orbit, the variational equation of the orbit, or state transition matrix. Thus analytical solutions to the orbit perturbation problem are the main focus of this work. The majority of extensive studies made mainly in the late 50's to 60's on this subject considers the general case of orbits, so that the solutions are extremely lengthy and complex. Due to the conventional methods they have chosen, the solutions have a singularity when the eccentricity approaches zero and the argument of perigee becomes undefined. The new description of the perturbed motion of near circular orbits is developed in this work, which does not have a singularity when the eccentricity is zero. This novel description is a natural expansion of the epicyclic motion of a small eccentric orbit, which results in a much simpler expression in the solutions and provides a greater understanding of orbital geometry. A fully analytical orbit determination system is also developed based on this epicyclic description of a perturbed orbit. As this orbit estimator requires no numerical integration scheme, it has extensive computational advantages and suits most onboard applications. This analytical orbit estimator is practically implemented onboard UoSat-12, which is Surrey's 350 kg class minisatellite. It has been operated for more than two years, and has demonstrated reliable autonomous onboard orbit determination. The in-orbit orbit determination results as well as the evaluations of practical accuracy are also presented.

This thesis considers the application of neural networks to automotive suspension systems. In particular their ability to learn non-linear feedback control relationships. The speed of processing, once trained, means that neural networks open up new opportunities and allow increased complexity in the control strategies employed. The suitability of neural networks for this task is demonstrated here using multilayer perceptron, (MLP) feed forward neural networks applied to a quarter vehicle simulation model. Initially neural networks are trained from a training data set created using a non-linear optimal control strategy, the complexity of which prohibits its direct use. They are shown to be successful in learning the relationship between the current system states and the optimal control.

The intense global competition that manufacturing companies face today results in an increase of product variety and shorter product life cycles. One response to this threat is agile manufacturing concepts. This requires materials handling systems that are agile and capable of reconfiguration. As competition in the world marketplace becomes increasingly customer-driven, manufacturing environments must be highly reconfigurable and responsive to accommodate product and process changes, with rigid, static automation systems giving way to more flexible types. Automated Guided Vehicle Systems (AGVS) have such capabilities and AGV functionality has been developed to improve flexibility and diminish the traditional disadvantages of AGV-systems. The AGV-system design is however a multi-faceted problem with a large number of design factors of which many are correlating and interdependent. Available methods and techniques exhibit problems in supporting the whole design process. A research review of the work reported on AGVS development in combination with simulation revealed that of 39 papers only four were industrially related. Most work was on the conceptual design phase, but little has been reported on the detailed simulation of AGVS. Semi-autonomous vehicles (SA V) are an innovative concept to overcome the problems of inflexible -systems and to improve materials handling functionality. The SA V concept introduces a higher degree of autonomy in industrial AGV -systems with the man-in-the-Ioop. The introduction of autonomy in industrial applications is approached by explicitly controlling the level of autonomy at different occasions. The SA V s are easy to program and easily reconfigurable regarding navigation systems and material handling equipment. Novel approaches to materials handling like the SA V -concept place new requirements on the AGVS development and the use of simulation as a part of the process. Traditional AGV -system simulation approaches do not fully meet these requirements and the improved functionality of AGVs is not used to its full power. There is a considerflble potential in shortening the AGV -system design-cycle, and thus the manufacturing system design-cycle, and still achieve more accurate solutions well suited for MRS tasks. Recent developments in simulation tools for manufacturing have improved production engineering development and the tools are being adopted more widely in industry. For the development of AGV -systems this has not fully been exploited. Previous research has focused on the conceptual part of the design process and many simulation approaches to AGV -system design lack in validity. In this thesis a methodology is proposed for the structured development of AGV -systems using simulation. Elements of this methodology address the development of novel functionality. The objective of the first research case of this research study was to identify factors for industrial AGV -system simulation. The second research case focuses on simulation in the design of Semi-autonomous vehicles, and the third case evaluates a simulation based design framework. This research study has advanced development by offering a framework for developing testing and evaluating AGV -systems, based on concurrent development using a virtual environment. The ability to exploit unique or novel features of AGVs based on a virtual environment improves the potential of AGV-systems considerably.

This thesis investigates the principle of co-ordination of chassis subsystems by proposing a new control structure for co-ordinating active steering technologies and a brake based directional stability controller. A non-linear vehicle handling model was developed for this study using the Mattab and Simulink tools. This consists of a 4 degree of freedom (d. o. f) lumped-parameter model that includes longitudinal, lateral, yaw and roll motions with quasi-static longitudinal load transfer effects including non-linear suspension and tyre descriptions. The non-linear vehicle dynamics are discussed for the whole operating regime and two specific driving tasks are identified, steerability and stability. In the context of the vehicle states these are yaw rate control and side slip angle bounding respectively. Linear active steering controllers for front, rear and four wheel steering are designed and evaluated in the context of the vehicle handling problem throughout the non-linear operating regime to assist the driver in the two driving tasks previously defined. It is shown through the analysis of the vehicle dynamics in the Chapter 3 that linear controllers can be used to significantly improve the handling behaviour of a non-linear vehicle when only one active input is considered, however when controlling two active inputs, non-linear multivariable approach is required to deal with the strongly coupled nature of the vehicle handling with respect to front and rear steering inputs. A brake based stability system that reflects the state of the art is implemented. The work then proposes a novel co-ordination controller structure for coordination of an active steering controllers and a brake based stability controller for improving to vehicle handling control. The controller was assessed both in steady state and transient tests selected to simulate real world driving manoeuvres over the whole non-linear vehicle handling regime. The co-ordination controller is found to lead to a trade-off between stability and limit cornering performance. The proposed structure improves vehicle stability and reduces interactions in the longitudinal vehicle motion. A detailed discussion of the implications of a coordinated control approach showing it to be a powerful tool providing, the interactions can be conveniently related vehicle handling task and that an appropriate measure of vehicle performance is available. The limitations of the approach are discussed. The most significant limitations being a) the difficulty in proving the optimalty of a heuristic control structure, b) the difficult in assessing the controller behaviour and its interaction with a real driver and c) the likely complexity of the rule base for coordinating more than 2 or 3 systems or describing more complex interactions than were observed here.

This study was concerned with improvement and validation of a thermodynamic spark ignition engine simulation code developed in Leeds. Experimental validation data were generated using a central ignition, disc-shaped combustion chamber variant of a ported single-cylinder research engine with full-bore overhead optical access. These data included simultaneous measurement of cylinder pressure and flame position at different operating conditions. The engine was skip fired (fired once every five cycles), to remove residuals and ensure well defined in-cylinder fuel-air mixture for simulation. Flames were imaged using a digital camera capturing the light emitted from the flame ("natural light"). New methods were developed to process the pressure and film data. Flame pictures were processed to determine enflamed area, mean flame radius and flame centroid. Parameters were also developed to describe flame "circularity" ("shape factor") and to describe asymmetry of flame approach to the cylinder walls ("active perimeter fraction", APF). Time-base crank angle records allowed evaluation of engine speed variation within a cycle and mean engine speed for a cycle. Although generated principally for model validation, the experimental results proved interesting in their own right. Middle, slow and fast cycles were defined for each condition. Analysis of these cycles suggested that there was no correlation between the initial flame centroid displacement, its locus over the flame propagation period or the flame "shape factor" and the speed of combustion and pressure development. As the flame approached the wall, the active perimeter fraction fell in a similar manner for all the middle cycles. Substantial modifications were made to a pre-existing thermodynamic engine cycle code. Deficiencies in the blowby, heat transfer and thermodynamic aspects were corrected. An additional ("Zimont") turbulent burning velocity sub-model and a new routine for the influence of engine speed variation within a cycle were incorporated into the code. The active perimeter fraction parameter function determined in the experiments was encoded to allow for the effects of flame-wall contact on entrainment rate during the late flame propagation. A radial stratified charge model was also developed. Burned gas expansion over the flame propagation period was shown to significantly change the unburned gas charge stratification from the initial variation. Two types of initial stratification (linear and parabolic distributions, rich of the centre and lean close to the wall) were imposed. Faster combustion development was observed in both cases, c. f that for equivalent homogeneous charge. Good agreement was observed between experimental results and "Zimont model" predictions at different equivalence ratios and engine speeds. Other computations using the pre-existing Leeds K and KLe correlations gave reasonable predictions at the various engine speeds and at rich conditions; however, they yielded slower results than experimentally observed for lean conditions.

This thesis presents a complete vision-based navigation system that can plan and follow an obstacle-avoiding path to a desired destination on the basis of an internal map updated with information gathered from its visual sensor. For vision-based self-localization, the system uses new floor-edges-specific filters for detecting floor edges and their pose, a new algorithm for determining the orientation of the robot, and a new procedure for selecting the initial positions in the self-localization procedure. Self-localization is based on matching visually detected features with those stored in a prior map. For planning, the system demonstrates for the first time a real-world application of the neural-resistive grid method to robot navigation. The neural-resistive grid is modified with a new connectivity scheme that allows the representation of the collision-free space of a robot with finite dimensions via divergent connections between the spatial memory layer and the neuro-resistive grid layer. A new control system is proposed. It uses a Smith Predictor architecture that has been modified for navigation applications and for intermittent delayed feedback typical of artificial vision. A receding horizon control strategy is implemented using Normalised Radial Basis Function nets as path encoders, to ensure continuous motion during the delay between measurements. The system is tested in a simplified environment where an obstacle placed anywhere is detected visually and is integrated in the path planning process. The results show the validity of the control concept and the crucial importance of a robust vision-based self-localization process.

A three dimensional implicit multiblock Navier-Stokes solver for hovering rotor vortical flow simulations has been developed. The governing equations used are cast in an attached blade rotating frame. Two formulations of the governing equations using the relative or absolute velocity as variables respectively are employed and investigated. The Osher's approximate Riemann solver is used for the convective fluxes evaluation. A modified MUSCL scheme is employed for improving the accuracy of the discretisation for the in viscid fluxes. A Block Incomplete Lower and Upper Decomposition (BILU) is adopted for solving the linear system resulted from the use of an implicit scheme. Special treatment for the terms, including extra flux terms and source terms, arising from the non-inertial reference system are implemented. A multiblock technique is used to obtain the exibility for quality grid generation. The suitability of different grid topologies for vortex wake capturing is demonstrated. Numerical tests show that significant improvement in computational efficiency is achieved by utilising the BILU implicit scheme in both fixed wing and hovering rotor calculations. Numerical simulations also demonstrate Navier-Stokes solutions give more accurate results than that from Euler solutions, especially in transonic tip speed cases. Computed results including surface pressure distributions and tip vortex trajectories are compared with the experimental data, which shows that the developed solver and the numerical scheme can simulate hovering rotor flows with good accuracy.

This study investigates a novel methodology for the preliminary design of aeroengines. This involves the modelling of the disciplines that affect the engine's requirements and constraints, their implementation in software format and their coupling into a single unit. Subsequently, this unit is interfaced with an optimiser software. The resulting multidisciplinary optimisation (MDO) tool allows the automation of the traditional, human-based preliminary design process. The investigation of the above-mentioned novel methodology is carried out through the development of a "pilot" MDO tool and its subsequent utilisation in three case studies, characterised by different optimisation scenarios. The selection of each case study is motivated by current research questions, such as aviation's contribution to climate change or the attractiveness of specific novel propulsion concepts. The outcome of the pilot MDO study is considered successful and has been well received by several academic and industrial aero-engine organisations. The choice of the disciplines and of their modelling fidelity allowed a realistic representation of the main disciplinary interactions and tradeoffs that characterise the important phase of preliminary design. The computational effort involved in the solution of the optimisation studies was found to be acceptable, and no major reprogramming was required when different optimisation scenarios were considered. The case studies were investigated with an ease and comprehensiveness that would not have been achievable through a human-based parametric analysis. The positive experience with the pilot MDO tool suggests that an automated methodology for the preliminary design of aero-engines is feasible, applicable and valuable. Its adoption can provide substantial advantages over the traditional human-based approach, such as a reduction in human effort, costs and risk. From this perspective, the pilot study constitutes a first step towards the development of a full-scale MDO tooL usable by aero-engine manufacturers. In the near future, issues like climate change could drive significant modifications in airframe and engine design. A preliminary design MDO tool is therefore timely, and has the potential of making a significant contribution.

The hovering flight of a micro air vehicle was investigated. Various flight control concepts, inspired by observation of insect and bird flight, were investigated in some detail. The concepts make use of flap frequency or phase between the flap and pitch attitudes of the wing to control the force magnitude. Tilt of the stroke plane or fuselage was used to vector the force. A flight control system was designed for each concept investigated. The investigation has revealed that the preferred control concept is one in which force vectoring is achieved by the fuselage tilt through a shift in the centre of gravity location while the force magnitude is controlled by the phase between pitch and flap attitudes. This has the advantage of reducing the vehicle weight while at the same time relaxing the demand of extremely high frequency actuators. The equations of motion based on a multi-body representation of a flapping wing micro air vehicle were derived and these form the basis for the SIMULINK flight simulation program used to carry out the above investigation. The aerodynamic model used for the simulation was obtained from force measurements with a flapping mechanism that allows the model wing to oscillate with two degrees of freedom (flap and pitch). During these measurements, the phase angle between the flap and pitch angles of the model wing was varied to determine the effects on the force magnitude and direction.

This thesis describes the development of a generic design methodology for variable camber flap systems for transport aircraft, intended to be used for cruise and low-speed operations. The methodology was structured after several revisions were performed on conventional high-lift device design methodologies for existing transport aircraft. The definition and detail explanations are given at every phase of the methodology. A case study was performed in order to give an example of the implementation of the methodology where a transport aircraft called A TRA, a design study from previous PhD report, was taken as a model. Experimental work could not be performed, due to budget constraints, so the case study was only carried out using computer-based analyses. Software packages such as MSES-code (a Computational Fluid Dynamic software), CATIA and PATRANINASTRAN were used for this case study to analyse aerodynamic characteristics, layout as well as simulation and structure analyses respectively. The results obtained showed that it was practically feasible to deploy such a high-lift device to transport aircraft when the effect from aerodynamic loads gave minimum effect on structural deformation. The deflections of the flap as well as spoilers under critical loads were below the allowable limits, which had a minimal effect due to the additional lift force generated from the movable surfaces.

This thesis presents investigations into dynamic modelling and control of a flexible manipulator system. The work on dynamic modelling involves finite element and symbolic manipulation techniques. The control strategies investigated include feedforward control using command shaping techniques and combined feedforward and feedback control schemes. A constrained planar single-link flexible manipulator is used as test and verification platform throughout this work. Dynamic model of a single-link flexible manipulator incorporating structural damping, hub inertia and payload is developed using the finite element method. Experiments are performed on a laboratory-scale single-link flexible manipulator with and without payload for verification of the developed dynamic model. Simulated and experimental system responses to a single-switch bang-bang torque input are presented in the time and frequency domains. Resonance frequencies of the system for the first three modes are identified. The performance and accuracy of the simulation algorithm are studied in comparison to the experimental results in both domains. The effects of damping and payload on the dynamic behaviour of the manipulator are addressed. Moreover, the impact of using higher number of elements is studied. The application of a symbolic manipulation approach for modelling and performance analysis of a flexible manipulator system is investigated. System transfer function can be retained in symbolic form using this approach and good approximation of the system transfer function can be obtained. Relationships between system characteristics and parameters such as payload and hub inertia are accordingly explored. Simulation and experimental exercises are presented to demonstrate the effectiveness of the symbolic approach in modelling and simulation of the flexible manipulator system. Simulation and experimental investigations into the development of feedforward control strategies based on command shaping techniques for vibration control of flexible manipulators are presented. The command shaping techniques using input shaping, low-pass and band-stop filters are considered. The command shaping techniques are designed based on the parameters of the system obtained using the unshaped bang-bang torque input. ii Abstract Performances of the techniques are evaluated in terms of level of vibration reduction, time response specifications, robustness to error in natural frequencies and processing times. The effect of using higher number of impulses and filter orders on the system performance is also investigated. Moreover, the effectiveness of the command shaping techniques in reducing vibrations due to inclusion of payload into the system is examined. A comparative assessment of the performance of the command shaping techniques in vibration reduction of the system is presented. The development of hybrid control schemes for input tracking and vibration suppression of flexible manipulators is presented. The hybrid control schemes based on collocated feedback controllers for rigid body motion control with non-collocated PID control and feedforward control for vibration suppression of the system are examined. The non-collocated PID control is designed utilising the end-point deflection (elastic deformation) feedback whereas feedforward control is designed using the input shaping technique. The developed hybrid schemes are tested within the simulation environment of the flexible manipulator with and without payload. The performances of the control schemes are evaluated in terms of input tracking capability and vibration suppression of the flexible manipulator. Initially, a collocated PD utilising the hub-angle and hub-velocity feedback signals is used as a feedback controller. Subsequently, to achieve uniform performance in the presence of a payload, a collocated adaptive control is designed based on pole-assignment self-tuning control scheme. Lastly, a comparative assessment of the performance of the hybrid control schemes is presented.

Numerical and experimental and investigations have been conducted on a full-scale, high downforce rear wing from a Ferrari Formula One racing car. The wing comprised a main- plane, vane and flap elements incorporating substantial aft camber and for the first time, air jet vortex generators. This study focuses on the wing performance at 19° incidence. Original numerical investigations were conducted using the CFX-4.2 finite volume, Navier-Stokes, fluid flow solver using non-orthogonal, body-fitted grids. All flows were modelled as steady state, incompressible and fully turbulent using the standard k - e turbulence model for closure of the Navier-Stokes equations. Two-dimensional numerical studies capture the performance trends of the high down- force wing. When compared with the experiments, the downforce is generally overpredicted by up to 28%. In the three-dimensional numerical studies performed, flow separation is predicted on the suction surface of the mainplane. The application of air jets is predicted to reduce the amount of flow separation through an enhancement of the skin friction above that seen on the model without air jets. An increase in downforce is also predicted for the air jet equipped wing. Some modifications were made to the wing to facilitate its testing in the City University Low Speed T2 Wind Tunnel at 35 and 40 m/s. These were the installation of the air jets, static pressure orifices, and the fitting of endplates. Boundary-layer control was not applied to the endplates. In the experiments, at high angles of incidence, the wing experiences incipient flow separation on the suction surface of the mainplane. The application of air jets reduces this flow separation and also increases the downforce generated by the wing over that of the wing without air jets. The interactions of the experimental and numerical solutions reveal the mechanisms by which the air jets enable the wing to generate more downforce. Nevertheless, additional work is needed to address issues such as the degree of two dimensionality of the flow fields in the experiments and grid sensitivity of the numerical results.

The goal of the research was to investigate a low cost bi-propellant engine of 40N thrust, suitable for integration into a small spacecraft. Small spacecraft are often launched as secondary payloads, where the primary spacecraft dictates the orbit. Thus propulsion is fast becoming a necessity to change the initial orbit into the mission-required orbit. The low-cost driver forced the use of non-toxic or 'green' propellants and the imposed volume constraints drove the requirement for a high density Isp. The propellant combination chosen was kerosene and hydrogen peroxide (HTP), both readily available and cheap liquids. Unfortunately HTP suffers from the intrinsic decomposition into oxygen and water during storage, which in a sealed tank causes the pressure to rise until rupture occurs. The compatibility of fluoropolymer and aluminium tank liner materials was measured through decomposition rate determination, chemical analysis and mechanical pull tests. The results demonstrated that while pure aluminium is superior to the fluoropolymer FEP, the latter has the ability to passively vent oxygen. This enabled a passively vented tank to be produced, which demonstrated sealed storage over 18 days. In order to maintain the low cost approach, high temperature alloys for the thruster were avoided. A range of cooling options were considered, however for the purpose of maximising the density Isp and minimising the complexity of the engineering, the novel decomposed HTP cooling system was chosen. The theory was evaluated with five practical engines built and tested. Combustion experiments determined the ignition conditions, combustion efficiency and stability. Cooling experiments were executed to determine the effectiveness of nitrogen and decomposed hydrogen peroxide coolant for the chamber and nozzle of the engine. The test data showed that this form of cooling is effective and a density Isp performance comparable to a commercial hypergolic bipropellant engine is possible.

This thesis presents laboratory and field studies into the effects of solar radiation on the thermal comfort of vehicle occupants. Whilst, thermal comfort has been widely studied in built environments, there have been relatively few studies into thermal comfort in vehicles. Those studies that have been conducted have noted that the effect of solar radiation is considerable in these confined microclimates. The aim of this thesis was to provide baseline data for the effects of solar radiation on thermal sensation and determine how this information can be integrated to provide a method for the assessment of vehicle thermal comfort. This was achieved using a specially constructed whole body solar chamber in a series of four laboratory studies looking at different aspects of solar radiation on human thermal comfort and an extensive field trial conducted in Seville, Spain. The laboratory studies were as follows:- 1, The effect of the intensity of direct simulated solar radiation on human thermal responses. Eight male subjects were exposed to 4 different intensity solar radiation conditions. Physiological and psychological measurements were taken. It was established that a mean response to 200 Wm"2 of direct simulated solar radiation will give a thermal sensation shift of one positive scale point. 2, The effect of the spectral content of simulated solar radiation on human thermal responses. Eight male subjects were exposed to 4 different spectral radiation conditions, with the same total radiation intensity, 400 wm·2 • There was found to be no significant difference in the thermal sensation responses due to spectra. 3, The effects of glazing type on human thermal comfort responses. Eight male subjects were exposed to 4 different automotive glazings, with a fixed external solar radiation level of 1000 wm·2 • The spectral qualities of glazing can significantly effect human thermal comfort. The lower the transmission of visible radiation through the glazing, the lower the thermal sensation felt by subject in a neutral environment. 4, The effect of direct short wavelength and long wavelength radiation on human thermal comfort. Nine male subjects were exposed to short wavelength, long wavelength and combined short and long wavelength radiation. For the conditions investigated it was established that the addition of reradiation from internal components has an effect on thermal sensation when combined with direct solar radiation. However, it is not considered that it will be a major factor in a real world situation, as dashboards generally do not maintain high surface temperatures in vehicles without high air temperatures. Using the data collected in the laboratory studies a predictive model, PMV sotu, was developed which integrated directed solar radiation into an existing thermal comfort model (PMV) in the form of a factor, Rsolar· Rsolar is a correction factor for the addition of short wavelength radiation which converts actual measured solar radiation to a thermal sensation scale adjustment The PMV solar model was validated with other models in field trials conducted in Seville, Spain. Four male subjects, undertook a series of 32, one hour long experiments over 8 days, whilst travelling on a Spanish highway. Environmental, physiological and psychological measurements were taken throughout the experiments to provide data for validation of THE PMV solar model. The assessment of human thermal comfort in vehicles is complex. Variation in environmental parameters in terms of both spatial and temporal changes, make accurate prediction of thermal comfort difficult. However, the PMV solar model provides an improved level of prediction of the state of thermal comfort of the vehicle occupants, in environments which have a high solar radiation level over existing thermal indices.

Exhaust Gas Recirculation (EGR) is one of several technologies that are being investigated to deliver future legislative emissions targets for diesel engines. Its application requires a detailed understanding of the thermofluidic processes within the engine's charge air system. A fully validated Computational Fluid Dynamics (CFD) process is one way of providing this understanding. This thesis describes how a process was developed using validation data from a four-branch diesel engine inlet manifold with a secondary EGR inlet. The validation and verification technique adopted, divided the complex flow problem into simpler elemental flow problems. Knowledge on these simple problems was, in some cases, found to be well documented in published literature. In other cases, additional detailed experimental validation and verification studies were carried out to supplement published information. Knowledge from these simple problems was utilised to develop the main CFD process and to enhance understanding of the calculation uncertainties.