In this document, research into the modelling and analysis of current and concept vehicles for the purpose of enhancing vehicle handling is summarised. This work is recounted in detail in a portfolio of reports that has been submitted for the degree of Doctor of Engineering. The portfolio includes fifteen submissions, eleven of which are concerned with the analysis and simulation of drivers' steering behaviour. Two relate to a novel suspension concept. One addresses a current problem caused by suspension variability and one introduces a process for selecting between new suspension concepts. Each of these fifteen submissions is summarised in this document. In addition, the order in which it is recommended that these submissions be read is listed. In section 4, a project summary of the research into the analysis and simulation of drivers' steering behaviour is presented. Existing models of drivers' steering behaviour are reviewed. Vehicle tests that illustrate the different steering styles used by different drivers are recounted. A driver model that simulates the steering behaviour exhibited in these tests is formulated . Then, this driver model is used to develop a switching strategy for variable dampers. It is demonstrated that the switching strategy enhances vehicle handling and reduces the roll experienced by drivers during a handling manoeuvre. Finally, it is verified that this research complies with the requirement of the degree of Doctor of Engineering to demonstrate innovation in the application of knowledge to the engineering business environment. This is achieved by specifying eight examples of where new ideas and methods have been applied to address current issues within the automotive industry.

The energy management system (EMS) of hybrid electric vehicle controls the operation of two power plants; electric machine/battery and typically engine. Hence the fuel economy and emissions of hybrid vehicles strongly depend on the EMS. It is known that considering the future trip demand in devising an EMS control strategy enhance the vehicle and component performances. However existing such acausal EMS cannot be used in real time and would require prior knowledge of the trip vehicle speed profile (trip demand). Therefore rule based EMS which considers instantaneous trip demand in devising a control strategy are used. Such causal EMS are real time capable and simple in design. However rule based EMS are tuned for a set of driving cycles and hence their performance is vulnerable in real world driving. The research question is “How to design a real time capable acausal EMS for a plug in hybrid electric vehicle (PHEV) that can adapt to the uncertainties of real world driving”. In the research, the design and evaluation of a proposed EMS to deal and demonstrate in scenarios expected in real world driving respectively were considered. The proposed rule based acausal EMS is formulated over the estimated vehicle trip energy and driving information. Vehicle trip energy is the electric (battery) energy required to meet the trip demand estimated using known driving information. Driving information that can be considered are driver style, route distance and road types like urban and extra urban, with traffic as a sub function. Unlike vehicle speed, vehicle trip energy is shown to be relatively less dynamic in real world driving. For the proposed EMS evaluation, a commonly used parallel PHEV model was simulated. For driving information EMS was not integrated to a navigation system but manually defined. Evaluation studies were done for a driver, and traffic was not considered for simplicity. In the thesis, vehicle performance and credentials for real world applicability (real time capability and adaptability) of the proposed acausal EMS are demonstrated for various scenarios in real world driving; varied initial SOC, sequence of road types, trip distance and trip energy estimation. Over the New European Driving Cycle (NEDC) the proposed EMS vehicle performance is compared to a conventional rule based EMS. The proposed EMS fuel economy improvement is up to 11% with 5 times fewer number of engine stop-starts. Similarly in the validation study, with no prior knowledge of trip vehicle speed profile, the fuel economy improvement is up to 29% with 7 times fewer number of engine stop-starts. The simulation duration of the proposed EMS is as good as conventional rule based EMS. Hence the proposed EMS is potentially real time capable. The proposed EMS can adapt to a wide variation in trip energy (±15%) estimation and still perform better than the conventional rule based EMS. The proposed EMS can tolerate variation in trip demand estimation and no prior knowledge of trip vehicle speed profile is required, unlike other acausal EMS studies in the literature. A new PHEV EMS has been formulated. Through simulation it has been seen to deliver benefit in vehicle performance and real world applicability for varied scenarios as expected in real world driving. The key new step was to use vehicle trip energy in the formulation, which enabled rule based EMS to be acausal and potentially real time capable.

The sensorimotor network receives a rich variety of somesthetic afferents and outputs considerable motor efferents, both of which drive experience-dependent plasticity in the system. It remains unclear to what extent subtle changes in somaesthesis and motor function extrinsic to the brain drive plasticity in the functional organisation and anatomy of the sensorimotor network. This thesis contains a series of multimodal MRI experiments to investigate how altered-use and disuse can induce plastic changes in the sensorimotor network of the human brain. In Chapter 3, a method of mapping digit somatotopy in primary somatosensory cortex at the single-subject level using 7.0 tesla fMRI was developed and applied for a study of healthy participants. Using a phase-encoding paradigm, digit representations were accurately mapped in under 10 minutes. These maps were reproducible over time and comparable to a standard block design. In Chapter 4, a further fMRI study assessed the potential for short-term reorganisation of digit representations in primary somatosensory cortex following a manipulation whereby the right index and right middle fingers were glued together for 24 hours. There was a marked shift in the cortical overlap of adjacent digits after the glued manipulation, not seen across an equivalent control period, providing strong evidence for short-term remapping of primary somatosensory cortex. In Chapter 5, a patient study investigated plasticity associated with chronic unilateral disuse of the upper limb. A cross-sectional comparison with control participants showed reduced grey matter density in the posterior right temporoparietal junction, and increased radial diffusivity in the white matter of the right superior longitudinal fasciculus, consistent with change in the right ventral attention network. A complementary longitudinal study in Chapter 6 investigated structural plasticity associated with rehabilitation of the disused limb. There were localised increases in grey matter density, notably in the right temporoparietal junction, further implicating a potential role for regions responsible for egocentric attention in regaining upper limb use. In Chapter 7, a further patient study investigated candidate predictive biomarkers at the sub-acute stage of stroke recovery, identifying CST-lesion cross-section and sensorimotor network strength as correlates of motor function, which warrant further study. The results of the studies presented in this thesis provide a novel insight into the nature and time frame of functional and structural plasticity associated with altered use and disuse. Further study of how subtle changes in our sensory and motor use shape the sensorimotor network is warranted, particularly in the context of disuse in non-neurological clinical populations.

This thesis describes research undertaken to improve computational modelling capability for the internal gearbox (IGB) of an aeroengine. Using the commercial computational fluid dynamics (CFD) software ANSYS FLUENT modelling methodologies for regions within the IGB have been developed, applied and refined. The IGB is a bearing chamber that houses the bearings that support the low pressure, intermediate pressure and high pressure shafts and in addition the spiral bevel gear pair that enable power to be taken from the high pressure shaft to power aircraft auxiliary systems. Within civil aeroengines parasitic power loss is a significant issue and as oil is used to lubricate and cool throughout the engine, this power loss largely manifests as increased heat-to-oil (HTO). A significant contributor to HTO is the IGB. The IGB contains complex geometry and a highly rotating two-phase flow consisting of films, droplets, ligaments and mist. Central to the IGB is the spiral bevel gear pair. Previous modelling research has shown that detailed modelling of flow behaviour is too computationally expensive for domains larger than a few teeth. Modelling the meshing gears with full flow fidelity is not yet feasible. In this thesis a significantly less computationally expensive approach is explored. The complex gear-shroud geometry is replaced by a smooth cone with momentum sources used to generate the required fluid motion. In the single phase model these momentum sources were tuned/calibrated against a full tooth model spanning four teeth. The model was capable of generating flow behaviour to within 5% of the full tooth model. Oil was added as a discrete phase with a film model but was less successful as oil motion is strongly affected by geometrical detail. A second approach to whole chamber modelling was proposed where the chamber is split into three zones and coupled via boundary conditions. Single phase investigation showed that the amount of swirl in the front chamber affects computed windage power loss with the maximum occurring at an inlet swirl number of around 0.5. The amount of swirl at gear entry does not however affect the amount of swirl at shroud exit and this shows that decoupling of the front chamber is viable. The investigations into the zonal coupling of the IGB highlighted the importance of the geometry of the rear chamber (between gear and bearing) on the flow through the gear. A study to investigate how best to model the two-phase flow in this rear chamber was conducted. Transient models showed the volume of fluid approach (VOF) to be inadequate whereas a full two-phase Eulerian model converged, yielding viable results consistent with limited qualitative experimental data. The computational model predicts significant accumulation of oil towards the bearing side of the chamber, with this oil stripping periodically through shroud exit slots to the front chamber. In the final part of the research a parametric study on several geometric features in the rear chamber was conducted using the developed two-phase modelling methodology. The chamber size, rear wall geometry, shroud exit slot location and size were investigated. The work in this thesis improves IGB modelling capability through - Establishing the capabilities and limitations of momentum source approach for full two-phase modelling of a shrouded gear - Establishing that to some extent a bearing chamber can be productively modelled as separate but linked zones - Identifying a successful modelling methodology for the high volume fraction two phase flow in the rear chamber In addition the work in this thesis shows that - For single phase flow the amount of swirl at gear inlet affects the windage power loss - The behaviour of oil in the rear chamber, including the amount trapped and the exit condition, are strongly affected by chamber geometry Guidelines for rear chamber design are also suggested.

Bearing Chambers in Aero-Engines are located near the rolling-element type of bearings which support the shafts and accomodate the resulting thrust loads. One of the main task of the bearing chambers is, beside an efficient scavenging of the lubricating oil, the cooling of the hot compartments. A very complex two-phase air-oil flow takes usually place in these bearing chambers consisting of oil droplet-laden air flows and shear-driven liquid wall films. The interaction of the droplets with the wall films is significantly influencing the wall heat transfer and the cooling performance of these systems. For this reason, a detailed characterization and modelling of the mass and momentum exchange between droplets and wall films for the unique impingement parameter range in bearing chambers is inevitable. This scientific report investigates the oil droplet impact dynamics for typical impingement regimes relevant to aero-engine bearing chambers. The application of a Direct Numerical Simulation (DNS) technique based on the Volume-of-Fluid (VOF) method and coupled with a gradient-based adaptive mesh refinement (AMR) technique allowed to characterize the drop impact dynamics during various single micro- and millimeter drop impacts onto thin and thick films. With the help of a special numerical treatment, a self-perturbing mechanism is installed that leads to the correct resolution of the crown disintegration process. The numerical methodology was thoroughly validated using the experimental results of millimeter sized drop impacts onto deep liquid pools. These results were developed with an enhanced back-illuminated high-speed imaging and Particle Tracking Velocimetry (PTV) technique. New insights into the cavity penetration, the crown’s breakup dynamics and the secondary droplet characteristics following a single drop impact have been developed with the help of the isolated variation of different parameters of influence. Particularly the influence of the Froude number, the impingement angle, and the cavity-wall interaction delivered results to date not reported in scientific literature. Beside the advances in fundamental physics describing the drop impact dynamics with the help of the numerical and experimental results, a set of correlations could also be derived. From these correlations, a drop-film interaction model was formulated that is suitable for the parameter range found in bearing chambers.

With recent developments in active vehicle drivelines and the trend towards the use of electric propulsion in road vehicles, the optimal way to distribute power in a vehicle has become an interesting area of research. Automobiles with Active Torque Distribution (ATD) capabilities demonstrate improved handling and stability, and there is the possibility that energy consumption could be reduced through better distribution of power. Motorcycles that can apply some of the drive torque at the front wheel exist, with the aim of increasing tractive force on low-friction surfaces. Research is required to investigate the effects of torque distribution on the handling and efficiency of motorcycles and automobiles. In this work, multibody models of both motorcycles and automobiles are created, and are verified with existing mathematical models. The vehicle models include the influences of suspension, aerodynamics and gyroscopic effects, and complex tyre models are used that account for combined lateral and longitudinal slip and the vertical loading situation. Simple driver models are used to control the speed and yaw rate of the vehicles while they undertake a series of on-road manoeuvres. Left–right torque vectoring is shown to be effective in the alteration of the steady-state handling characteristics of the automobile, and front–rear torque vectoring has a small effect at high speeds. A slight increase is possible in transient responsiveness at moderate speeds, but instabilities can be exacerbated at high speeds. In motorcycles, the torque distribution has only a small effect on handling in steady-state situations. During straight-running, the optimum efficiency of the both vehicles is shown to occur when the torque is distributed in proportion with the vertical load at the tyres. During cornering, a slight additional bias towards the front wheel(s) is beneficial. Despite the alteration in handling characteristics made available through ATD, the effects of weight distribution and tyre characteristics still dominate. At normal speeds, almost the same effect on automobile handling can be achieved through left–right torque vectoring in a front- or rear-wheel-drive vehicle, as in a four-wheel-drive vehicle. In these steady-state situations, the energy efficiency of the vehicles varies only by small amounts, with aerodynamic and lateral slip dissipations dominating. The models presented in this thesis, and the results and conclusions obtained from them, offer the designers of future vehicles useful information for the improvement of vehicle handling, efficiency and quality.

Thermal management is crucial in many engineering applications because it affects the electrical, material, and other properties of the system. A recent study focuses on the use of heat pipes for battery thermal management in electric vehicles, which explores a new area for heat pipe applications. The battery, as one and only energy source in an EV, establishes a vital barrier for automotive industry because it can make the car more expensive and less reliable. The modelling methodology developed in this thesis is a one-dimensional electrochemical model, decoupled and coupled with a three-dimensional flow and heat transfer model. A prototype for 2-cell prismatic battery cooling and preheating using heat pipes is developed, and a full experimental characterisation has been performed. The experimental results characterised system thermal performance as well as validating material properties/parameters for simulation inputs. Two surrogate cells filled with atonal 324 were used in this experiment. The eligibility of substituting atonal 324 for lithium-ion battery electrolytes has been assessed and confirmed. The consistency demonstrated between the finite element analysis and the experiment facilitates BTM simulation at pack level, which is a scale-up model containing 30 lithium-ion batteries. The study shows that heat pipes can be very beneficial to reduce thermal stress on batteries leading to thermally homogenous packs. Additionally, an attempt of integrating biomimetic wicks for ultra-thin flat plate heat pipes is made in response to space limitations in microelectronics cooling. To date, no one has devised an ultra-thin FPHP with enough vapour space by constructing different wicks for each heat pipe segment, especially under anti-gravity condition. It is thus interesting to see whether a new type of wick structure can be made to achieve an optimum heat transfer potential.

With the dramatic development of the automotive industry and global economy, the motor vehicle has become an indispensable part of daily life. Because of the intensive competition, vehicle manufacturers are investing a large amount of money and time on research in improving the vehicle performance, reducing fuel consumption and meeting the legislative requirement of environmental protection. Engine calibration is a fundamental process of determining the vehicle performance in diverse working conditions. Control maps are developed in the calibration process which must be conducted across the entire operating region before being implemented in the engine control unit to regulate engine parameters at the different operating points. The traditional calibration method is based on steady-state (pseudo-static) experiments on the engine. The primary challenge for the process is the testing and optimisation time that each increases exponentially with additional calibration parameters and control objectives. This thesis presents a basic dynamic black-box model-based calibration method for multivariable control and the method is applied experimentally on a gasoline turbocharged direct injection (GTDI) 2.0L virtual engine. Firstly the engine is characterized by dynamic models. A constrained numerical optimization of fuel consumption is conducted on the models and the optimal data is thus obtained and validated on the virtual system to ensure the accuracy of the models. A dynamic optimization is presented in which the entire data sequence is divided into segments then optimized separately in order to enhance the computational efficiency. A dynamic map is identified using the inverse optimal behaviour. The map is shown to be capable of providing a minimized fuel consumption and generally meeting the demands of engine torque and air-fuel-ratio. The control performance of this feedforward map is further improved by the addition of a closed loop controller. An open loop compensator for torque control and a Smith predictor for air-fuel-ratio control are designed and shown to solve the issues of practical implementation on production engines. A basic pseudo-static engine-based calibration is generated for comparative purposes and the resulting static map is implemented in order to compare the fuel consumption and torque and air-fuel-ratio control with that of the proposed dynamic calibration method. Methods of optimal test signal design and parameter estimation for polynomial models are particularly detailed and studied in this thesis since polynomial models are frequently used in the process of dynamic calibration and control. Because of their ease of implementation, the input designs with different objective functions and optimization algorithms are discussed. Novel design criteria which lead to an improved parameter estimation and output prediction method are presented and verified using identified models of a 1.6L Zetec engine developed from test data obtained on the Liverpool University Powertrain Laboratory. Practical amplitude and rate constraints in engine experiments are considered in the optimization and optimal inputs are further validated to be effective in the black box modelling of the virtual engine. An additional experiment of input design for a MIMO model is presented based on a weighted optimization method. Besides the prediction error based estimation method, a simulation error based estimation method is proposed. This novel method is based on an unconstrained numerical optimization and any output fitness criterion can be used as the objective function. The effectiveness is also evaluated in a black box engine modelling and parameter estimations with a better output fitness of a simulation model are provided.

This thesis presents closed loop control of active Gurney flaps on rotors. Firstly, it builds on the Helicopter Multi-Block 2 CFD solver of the University of Liverpool and demonstrates the implementation and use of Gurney flaps on wings, and rotors. The idea is to flag any cell face within the computational mesh with a solid, no slip boundary condition. Hence the infinitely thin Gurney can be approximated by “blocking cells” in the mesh. Comparison between thick Gurney flaps and infinitely thin Gurneys showed no difference on the integrated loads, the same flow structure was captured and the same vortices were identified ahead and behind the Gurney. The results presented for various test cases suggest that the method is simple and efficient and it can therefore be used for routine analysis of rotors with Gurney flaps. The potential effect of a Gurney flap all over the performance of the W3-Sokol rotor blade in hover was studied next. A rigid blade was first considered and the calculations were conducted at several thrust settings. The Gurney flap was extended from 46%R to 66%R and it was located at the trailing edge of the main rotor blade. Four different sizes of Gurney flaps were studied, 2%, 1%, 0.5% and 0.3% of the chord, and the biggest flap proved to be the most effective. A second study considered elastic blades with and without the Gurney flap. The results were trimmed at the same thrust values as the rigid blade and indicate an increase of aerodynamic performance when the Gurney flap is used, especially for high thrust cases. Moreover, the performance of the W3-Sokol rotor in forward flight with and without Gurney flap was tested. Rigid and elastic blade models were considered and calculations were guided using flight test data. The Gurney flap was extended from 40%R to 65%R, while the size of the Gurney was selected to be 2% of the chord based on the hover study. All results were trimmed to the same thrust as flight tests. The harmonic analysis of the flight test data proved to be a useful tool for identifying vibrations on the rotor caused by stall at the retreating side, and a carefully designed Gurney flap and actuation schedule were essential to alleviate the effects of flow separation. The last part of the thesis is dedicated to a closed loop actuation of the Gurney flap based on the leading edge pressure divergence criterion. The effect of the Gurney flap on the trimming of a full helicopter model, as well as the handling qualities of the rotorcraft were investigated. To the author’s knowledge this is the first attempt to study the effect of active Gurney flaps on elastic rotors with 3D CFD in a closed loop control for retreating blade stall alleviation and hover performance enhancement. The idea is that Gurney will stay deployed during the hover and it will be actuated based on the forward flight demands in order to enhance the rotorcraft capabilities.

The research reported here was driven by a desire to obtain a prediction method for helicopter rotor performance that would have sufficient resolution to evaluate changes to the design of the blade tip. This thesis examines the effectiveness of Computational Fluid Dynamics (CFD) methods to solve this problem. An accurate, high-fidelity prediction is essential to quantify the performance of a new rotor tip shape which hitherto could not be properly assessed by a traditional approach. The CFD method lends itself to the resolution of the compressible, viscous flow around the helicopter blade tip. Starting from the surface shape required to generate a grid, together with the flow conditions, the flowfield naturally evolves from the numerical solution of the Navier-Stokes equations, based on the principles of conservation of mass, momentum and energy. Thus both the flow physics and the geometry of the tip are fully modelled by this technique. In order to demonstrate the process, the Helicopter Multi-block solver (HMB) is used to predict the performance of a series of example tail rotor configurations. The various tip shapes are evaluated and compared, initially using an Euler approach to economically cover a wide range of designs, before going on to apply the Navier-Stokes method. The concepts behind each of the tail rotor blade (TRB) tip designs are explained in the thesis. As further computational resources became available, the datum blade, and the down-selected Kuchemann-like and anhedral-Kuchemann tip blades were the subject of Navier-Stokes predictions. Early in this work, the numerical method was validated against published data, and was also compared to existing model tail rotor test data for blades having different twist. In the central part of this thesis, the computational results are further analysed to reveal the influence of blade design changes on the time-averaged induced flow, and to extract more familiar aerodynamic parameters such as the angle of attack from the 3D rotor computations. Steady Navier-Stokes predictions were obtained over a range of pitch angles such that the induced power factor could be reliably determined and the trends on profile power could also be established for the selected tip shapes. The research reported in this thesis has established that this numerical approach provides a good prediction of rotor performance, adequately resolving the flow-field and tip aerodynamics. Since the assessment of helicopter rotors may involve additional interactional effects, or a degree of unsteady flow due to operating at high pitch angles near the onset of stall, an unsteady case was also demonstrated for a tail rotor blade adjacent to a fin. It is concluded that only by using a CFD approach can a sufficiently high-fidelity prediction be obtained for helicopter rotor aerodynamics to allow progressive enhancements of future helicopter blade designs.