Viewing 1 to 11 of 11
Technical Paper
Roberto Sabatini, Terry Moore, Chris Hill, Subramanian Ramasamy
Abstract Global Navigation Satellite Systems (GNSS) can support the development of low-cost and high performance navigation and guidance architectures for Unmanned Aircraft Systems (UAS) and, in conjunction with suitable data link technologies, the provision of Automated Dependent Surveillance (ADS) functionalities for cooperative Sense-and-Avoid (SAA). In non-cooperative SAA, the adoption of GNSS can also provide the key positioning and, in some cases, attitude data (using multiple antennas) required for automated collision avoidance. A key limitation of GNSS for both cooperative (ADS) and non-cooperative applications is represented by the achievable levels of integrity. Therefore, an Avionics Based Integrity Augmentation (ABIA) solution is proposed to support the development of an Integrity-Augmented SAA (IAS) architecture suitable for both cooperative and non-cooperative scenarios.
Technical Paper
J Barker, Jacqueline Reid, M Piggott, Mike W. Fay, A Davies, Christopher Parmenter, N Weston, C Snape, D Scurr, Sarah Angel-Smith
The effect of legislation in driving towards lower emissions has seen significant changes in injector design, (common- rail) and fuel composition (ULSD). This has led to numerous reports of deposits throughout the vehicle diesel system, filters, tanks, pumps and injectors. In recent examples, deposits internal to the fuel injector on the needle have become prevalent and characterisation of the deposits on the injector needle has become an industry priority. A number of studies have made progress on this but the deposits have proven difficult to fully characterise and often have an ineradicable nature, which makes analysis other than in situ difficult. This paper will describe for the first time the application of a number of surface techniques, in combination which not only provide characterisation data but also the ability to provide cross-sectional lifts out of the sample, which may then be the subject of further analysis.
Technical Paper
Philip Webb, Celine Michel, Amir Kayani, Mike Poad, Nirosh Jayaweera
A modern aircraft wing contains many complex pipes and ducts which, amongst other functions, form the fuel management and bleed air systems. These parts are often fabricated from thin sheet material using a combination of forming and welding and the manufacturing process is predominantly manual requiring highly skilled labor. Since each wing may only contain one or two of each part type the product volumes are very low, typically a few hundred per year. This means that conventional mass production approaches used in, for example the automotive industry, are not economically viable and the parts are thus disproportionately expensive. The current fabrication process involves splitting the component into parts that can be press formed from sheet, laser trimmed and then manually welded together in a fixture. This process requires a perfect fit between the parts whose quality is reliant on the initial forming process.
Technical Paper
P. Webb, C. Ye, M. To, S. Al-Thraa, A. Kayani
Measurement assisted assembly is one of the key emerging technologies in airframe manufacture. The use of metrology to assist with the assembly process can significantly reduce the cost and complexity of the required fixtures as well as reducing manual labor input and assembly time. Most of the existing systems use a single metrology system but this paper describes the development and deployment of a network based system that allows the deployment of multiple metrology systems to support either a single task or multiple tasks simultaneously.
Journal Article
D. MacMillan, A. La Rocca, P. J. Shayler, T. Morris, M. Murphy, I. Pegg
An experimental investigation of combustion cycle-by-cycle stability under cold idling conditions has been carried out on a Dl diesel to examine the influence of pilot fuel injection strategy. The engine is a single cylinder variant of a multi-cylinder design meeting Euro 4 emissions requirements. The engine build had a swept volume of 500cc and a compression ratio of 18.4:1. Work output and heat release characteristics have been investigated at test temperatures of 10, 0, −10 and −20°C and speeds in the range from 600 to 1400rpm. At the lowest temperature, −20°C, stability is sensitive to the timing of main injection and is prone to deteriorate with increasing engine speed. The influence of the number of pilot injections and pilot fuel quantity on stability has been explored. Best stability was achieved by increasing the number of pilot injections as temperature is lowered, from one at 10°C to two at −10°C and between two and four at −20°C.
Technical Paper
T. Wu, S. Bozhko, G. Asher, P. Wheeler, D. Thomas
This paper develops fast reduced-order models for generic aircraft electromechanical actuators (EMA). The models derivation is described in detail. It is shown that constant power load representation has its own dynamics that depend both on the principal machine parameters and upon the pulse-width modulation algorithm used. The accuracy specification cannot be met unless these dynamics are considered. The mechanism to take these dynamics into account by reduced-order models is proposed. Simulation results demonstrate the accuracy within the specified frequency bandwidth and the significant improvement in the computational time. The reported models can be used in a wide range of aircraft power system simulations.
Technical Paper
Paul J. Shayler, Lawrence Alger
Experimental investigations of intake and exhaust valve timing effects at part load have been carried out on a 4 cylinder, 1.6 l spark ignition engine. The effects of valve timing on charge dilution by residual gases, and on fuel consumption and emission characteristics, have been explored. The valve timings, and particularly the duration of the valve overlap period, strongly influence levels of charge dilution. The extent to which this accounts for the observed changes in specific fuel consumption and emissions with valve timings is investigated. Residuals gas fraction values have been determined at various steady operating conditions through the analysis of gas samples drawn from the cylinder near the tip of the spark plug. A gasoline direct injection fuel injector operating in reverse flow was used as a high-speed sampling valve. Brake specific values reflect a combination of changes in dilution and, at different brake loads, changes in pumping work.
Technical Paper
Paul J. Shayler, David K. W. Leong, Michael Murphy
Friction data have been acquired from motored engine tests on four designs of light duty automotive diesel engines with a swept capacity around two litres (1.8l-2.2l). The data cover temperatures at the start of motoring of -20°C and above, and motoring speeds from 200 rev/min to 1000 rev/min. Most tests were carried out using SAE 10W/30 oil. The breakdowns separated piston assembly, crankshaft assembly, valve train and auxiliary component contributions to friction mean effective pressure (fmep). The empirical coefficients and functions used in the engine friction model developed by Patton, Nitschke and Heywood (SAE 890836) have been modified to fit the low speed, low temperature test data without greatly affecting predictions for fully-warm conditions. The dependence of component contributions on oil viscosity during warm-up has been taken into account.
Technical Paper
P. J. Shayler, T. D. Brooks, G. J. Pugh, R. Gambrill
The paper outlines experimental investigations of fuel injection strategies which are possible using high pressure common rail fuel injection systems. Strategies using a split main with a pilot injection have been explored. The strategy variables were the ratio of the first to second part of the main, the separation between these and the timing of the start of main injection. Exhaust gas recirculation rate was a fourth variable. Pilot injection quantity and timing, and rail pressure were held constant. The influence on emissions and specific fuel consumption is described and the method of optimising settings is outlined. The manipulation of fuel injection settings to best meet optimisation targets for emissions and specific fuel consumption is described. The benefits compared to results for optimised single main injection are described, as are issues of strategy robustness.
Technical Paper
P. J. Shayler, A. J. Allen, A. L. Roberts
The paper reports the design of a model and HIL system produced to support the development and testing of Electronic Control Unit/Engine Management System (ECU/EMS) software for a V6 turbo-charged automotive diesel engine. The engine model, developed in Simulink, is compiled to execute on a dSpace platform and interacts with the ECU/EMS module in real time. The main features of the engine model are outlined. The configuration of the model and HIL components are described, and the performance of the system is illustrated and discussed. Practical decisions on the inclusion of real or virtual sensors and actuators, and other implementation issues, are explained. Recent and potential future applications of the system are described.
Technical Paper
P. J. Shayler, H. K. Ng
Kiva-3v Release 2 has been used to investigate combustion and emissions formation processes in a direct injection diesel engine with a high pressure common rail injection system. The influence of split main ratio and separation on NO and soot emissions have been of particular interest. Model validation has been based on comparisons with experimental data for heat release and engine-out emissions. Simulations have been carried out to explore the temporal development of combustion processes under typical part-load operating conditions. The results presented are for an engine speed and BMEP of 1600 rev/min and 6.76 bar, respectively.
Viewing 1 to 11 of 11


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