This thesis is concerned with the potential applications for in-cylinder ionisation probes for the feedback control of spark ignition engines. Such sensors are shown to yield useful qualitative information about the combustion process. Two different implementations of an in-cylinder ionisation probe are investigated - both types are demonstrated to have potential for specific control applications. The first implementation is a <i>Flame front sensor</i> - here an ionisation probe is used to determine the time of flame arrival at a position remote from the spark plug. This parameter is typically subject to a high degree of cyclic variability, but is generally sensitive to variables which affect the flame speed such as air/fuel ratio, turbulence characteristics etc. The flame arrival time is shown to be useful as an indicator of relative cylinder to cylinder variations. The general signal characteristics were determined for a range of engine conditions and a system for the real-time, feedback control of a fuel injection system was developed and demonstrated. Results showed that, with the controller implemented on a four cylinder engine, the lean misfire limit could be extended to higher air/fuel ratios and the brake specific fuel consumption was improved. The second implementation of a <i>Post-flame ionisation sensor</i> -- the residual ionisation in the burnt gases behind a flame front is used to provide a signal which is sensitive to cylinder temperature and pressure. The central electrode of the spark plug is conveniently located to produce such a signal -- providing precautions are taken to protect the signal circuitry from the high voltage ignition spark. The signal characteristics of the spark plug ionisation probe were evaluated. Applications of the signal to the feedback control of ignition timing and/or fuelling, based on the estimation of peak cylinder pressure arrival and knock intensity, are demonstrated.

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The performance requirements of turbofan engines demands a stability and transient capability beyond that associated with the past generations of gas turbine engines. The axial flow fan unit is most vulnerable to loading limitations due to the primary problems associated with the compression process, its sensitivity to inlet distortion and the difficulty to design for an overall optimum blade duty in a machine of wide radial blade loading distribution. The development of mathematical models with some capability of predicting the stable operating range of an axial flow fan has to overcome the difficulties associated with the modelling of the radially distinct flow regions and their dynamic interaction. ' The current investigation combined the available knowledge of one-dimensional models (based on the principles of conservation of mass, linear momentum and energy) with the assumptions of the parallel compressor theory, in order to develop a linearized system of equations for stability analysis (surge prediction). The stability conditions which emerged from this approach were applied on the experimentally derived characteristics of a low hub to tip ratio split flow fan in a manner which involved the modelling of the dynamic interaction of the inner and outer flow region of the fan. The development of the governing equations was achieved by applying one-dimensional flow analysis to the inner and outer section of the fan. Their interaction was modelled on the experimentally obtained radial movement of the splitter streamline and the discharge ,static pressure 'radial distribution. The inner and outer region were treated as a lumped volume element search operating on a local masflow averaged total pressure rise characteristic and alternatively acting in conjunction with a common nozzle and separate nozzles. The experimental investigation was carried out on a low hub totipratio two-stage split flow fan(with the facility of independent bypass and core throttles)in order to examine the localised and overall performance of such a fan(and the staling processes involved)and to enable the application of the stability analysis. The influence of reducing the distance between the fan flow spliter and the last bladerowasal so investigated, «The mathematical mode1s predicted the point of dynamic instability within 4.52 of the experimental observed mas flow rate and pressure is value.

The continuous growth in flight operations has led to public concern regarding the impact of aviation on the environment with its anthropogenic contribution to global warming. Several solutions have been proposed in order to reduce the environmental impact of aviation. However most of them are long term solutions such as new environmental friendly aircraft and engine designs. In this respect, management of aircraft trajectory and mission is a potential short term solution that can readily be implemented. Therefore, in order to truly understand the optimised environment friendly trajectories that can be actually deployed by airlines, it is important to investigate the impact of degraded engine performance on real aircraft trajectories at multi-disciplinary level. Several trajectory optimisation studies have been conducted in this direction in the recent past, but engines considered for the studies were clean and trajectories were ideal and simple. This research aims to provide a methodology to enhance the conventional approach of the aircraft trajectory optimisation problem by including engine degradation and real aircraft flight paths within the optimisation loop (framework); thereby the impact of engine degradation on optimum aircraft trajectories were assessed by quantifying the difference in fuel burn and emissions, when flying a trajectory which has been specifically optimised for an aircraft with degraded engines and flying a trajectory which has been optimised for clean engines. For the purpose of this study models of a clean and two levels of degraded engines have been developed that are similar to engines used in short range and long range aircraft currently in service. Degradation levels have been assumed based on the deterioration levels of Exhaust Gas Temperature (EGT) margin. Aircraft performance models have been developed for short range and long range aircraft with the capability of simulating (generating) vertical and horizontal flight profiles provides by the airlines. An emission prediction model was developed to assess NOx emissions of the mission. The contrail prediction model was adopted from previous studies to predict contrail formation. In addition, a multidisciplinary aircraft trajectory optimisation framework was developed and employed to analyse short range flight trajectories between London and Amsterdam and long range flight trajectories between London and Colombo under three cases. Case_1: Aircraft with clean engines, Case_2 and Case_3 were Aircraft with two different levels of degraded engines having a 5% and 10% Exhaust Gas Temperature (EGT) increase respectively. Three different multi objective optimisation studies were performed; (1) Fuel burn vs Flight time, (2) Fuel burn vs NOx emission, and (3) Fuel burn vs Contrails. Finally optimised trajectories generated with degraded engines were compared with the optimised trajectories generated with clean engines ... [cont].

The main scope of this thesis is the four stoke petrol engine performance tuning by ECU. The thesis analyses processes during engine management, describes and explains singular signals processed and generated by ECU. Designs measuring strings and optimal procedures for measuring on whose basis has been assembled optimal methodology leading to the optimalization of single operating mode of engine.

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Yes / The natural gas as an alternative fuel has economical and environmental benefits. Bi-fuel engines powered by gasoline and compressed natural gas (CNG) are an intermediate and alternative step to dedicated CNG engines. The conversion to bi-fuel CNG engine could be a short-term solution to air pollution problem in many developing countries. In this paper a mathematical model of a bi-fuel four-stroke spark ignition (SI) engine is presented for comparative studies and analysis. It is based on the two-zone combustion model, and it has the ability to simulate turbulent combustion. The model is capable of predicting the cylinder temperature and pressure, heat transfer, brake work , brake thermal and volumetric efficiency, brake torque, brake specific fuel consumption (BSFC), brake mean effective pressure (BMEP), concentration of CO2, brake specific CO (BSCO) and brake specific NOx (BSNOx). The effect of engine speed, equivalence ratio and performance parameters using gasoline and CNG fuels are analysed. The model has been validated by experimental data using the results obtained from a bi-fuel engine. The results show the capability of the model in terms of engine performance optimization and minimization of the emissions. The engine used in this study is a typical example of a modified bi-fuel engine conversion, which could benefit the researchers in the field.

Approved for public release, distribution is unlimited / Operational characteristics of a valveless pulse detonation engine system were characterized by experimental measurements of thrust, fuel flow, and internal gas dynamics. The multi-cycle detonation experiments were performed on an axis-symmetric engine geometry operating on an ethylene/air mixtures. The detonation diffraction process from a small 'initiator' combustor to a larger diameter main combustor in a continuous airflow configuration was evaluated during multi-cycle operation of a pulse detonation engine and was found to be very successful at initiating combustion of the secondary fuel/air mixture at high frequencies. The configuration was used to demonstrate the benefit of generating an overdriven detonation condition near the diffraction plane for enhanced transmission of the larger combustor. Results have shown that the addition of optical sensors, such as tunable diode lasers, to provide fuel profile data are invaluable for providing high fidelity performance results. The performance results demonstrated the ability of the valveless pulse detonation engine to run at efficiencies similar to valved pulse detonation engine geometries and may be a low cost alternative to conventional air-breathing propulsion systems. / Funded By: N00014OWR20226. / Lieutenant, United States Navy

This thesis evaluates the battery performance of two widely known game engines and compares the results to find the most battery friendly choice. Unity and Unreal Engine 4 are the two engines being compared; it aims to fill the need for research around mobile games battery performance. Smartphones battery life issues becomes more and more common with the powerful smartphones we use in today’s society. They are becoming faster every year, but the batteries stay the same. Power hungry games are not uncommon to find on the biggest game market that has surpassed the combined income of PC and Console games. Tests were performed on an Android system where multiple applications were tested while the battery consumption was measured. The applications are testing how different 2D or 3D components will impact the battery consumption compared to their baseline idling consumption. This thesis provides instructions on how the test applications were developed and which components were included. The findings show that the components had very little impact on the battery consumption for both Unity and Unreal Engine 4. Unity consumed between 1,1 – 1,4 % (36-42mAh) battery for all applications, Unreal Engine 4 consumed between 1,3 – 1,6% (39-48mAh) battery. This thesis conclusion is that Unreal Engine 4 game components require more battery power than the corresponding components of Unity. Therefore, Unity is according to the findings of this thesis a more battery friendly game engine for android games. These results mean that those who looks to create a smaller 2D or 3D game would get a more battery friendly application if they chose to use Unity. However, the results are limited because of how features like gyro, GPS and bigger applications were not included in the performed test cases.