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Porous wall permeability is one of the most critical factors for the estimation of backpressure, a key performance indicator in automotive particulate filters. Current experimental and analytical filter models could be calibrated to predict the permeability of a specific filter. However, they fail to provide a reliable estimation for the dependence of the permeability on key parameters such as wall porosity and pore size. This study presents a novel methodology for experimentally determining the permeability of filter walls. The results from four substrates with different porosities and pore sizes are compared with several popular permeability estimation methods (experimental and analytical), and their validity for this application is assessed. It is shown that none of the assessed methods predict all permeability trends for all substrates, for cold or hot flow, indicating that other wall properties besides porosity and pore size are important.

Engine Electronic Control (EEC) systems on spark ignition engines enable a high degree of performance optimisation to be achieved through strategy and calibration details in software, but development times and costs can be high. The range of functions performed by EEC systems, and the level of performance demanded, are increasing and new methods of development are required. In the paper, the use of neural networks in the development and implementation of open-loop control of air/fuel ratio during engine transient operating conditions is described. The investigation has addressed the definition of suitable networks, the procedure and data required to train these, and assessment of real-time performance of the implemented system. The potential benefits of the approach include reduced calibration effort and simplification of the control strategy.

China is the world’s largest automotive producer and has the world’s biggest automobile market. However, in the past decades, the development of China’s automotive industry has depended primarily on the foreign direct investment; domestic automakers have struggled in the lower ranks of car producers. In recent years, China’s automotive industry, supported by government policies, has been improving their Research and Development (R&D) capacity, to compete with their international peers. Against this background, China’s automotive industry requires a large number of R&D professionals who have not only a higher degree but also the applied and practical knowledge and skills of research. For the purpose of meeting the industry’s needs, a new Professional Automotive Engineering Masters Programme was launched in 2009, which aims to deliver the Masters to be the R&D professionals in the future.

This paper studies the feasibility and potential benefits of aligning recycled carbon fibres, in the form of short individual filaments, to manufacture fibre reinforced polymer composites. A review of fibre alignment processes is presented to provide insight into the different alignment technologies. The main focus is on wet hydrodynamic processes, which offer a high degree of alignment for discontinuous fibres. The process parameters that govern the alignment efficiency are also reported. The effect of alignment on fibre packing efficiency in the manufacture of composites is included, together with a report of preliminary fibre alignment results obtained from three different alignment processes.

Experimental studies have been undertaken on a single-cylinder HPCR diesel engine with a compression ratio of 15.5:1 to explore the effect of fuel injection strategy on cycle by cycle stability. The influence of the number, separation and quantity of pilot injections on the coefficient of variation of IMEP has been investigated at -20°C, 1000 rev/min, post-start idling conditions. Injection strategy and glow plug temperature trade-off has also been investigated at a range of soak temperatures. Up to four pilot injections have been used. For timing of the main injection near to the optimum, CoVIMEP values of 10% or better can be achieved. Closer spacing of injections improved stability and extended the range of timings to meet target stability. The best combinations of pilot number and pilot quantity varied with total fuel delivered.

The deterioration of combustion stability as lean operating limits and misfire conditions are approached has been investigated experimentally. The study has been carried out on spark ignition engines with port fuel injection and four-valves-per-cylinder. Test conditions cover fully-warm and cold operation, and ranges of air/fuel ratio, exhaust gas recirculation rates and spark timing. An approximate method of calculating gas/fuel ratio is described. This is used to show that combustion stability, characterised by the coefficient of variation of i.m.e.p., is a function of calculated gas/fuel ratio and spark timing until near to the limit of stability. A rapid deterioration in stability and the onset of weak, partial burning occurs at a gas/fuel ratio between 24:1 and 26:1 under fully-warm operating conditions, and around one gas/fuel ratio lower under cold operating conditions.

The effect of compression ratio on sensitivity to changes in start of injection and air-fuel ratio has been investigated on a single-cylinder DI diesel engine at fixed low and medium speeds and loads. Compression ratio was set to 17.9:1 or 13.7:1 by using pistons with different bowl sizes. Injection timing and air-to-fuel ratio were swept around a nominal map point at which gross IMEP and NOx values were matched for the two compression ratios. It was found that CO, HC and ISFC were higher at low compression ratio, but the soot/NOx trade-off improved and this could be exploited to reduce the fuel economy penalty. Sensitivity to inputs is generally similar, but high compression ratio tended to have steeper response gradients. Reducing compression ratio to 13.7 gave rise to a marked degradation of performance at light load, producing high CO emissions and a fall in combustion efficiency. This could be eased by reducing rail pressure, but the advantage in smoke emission was lost.

Cycle-by-cycle pressure data have been recorded for a spark ignition engine operating over a wide range of steady state and perturbed running condition. The data base has been analysed to derive mass fraction burnt, pressure development and work mean effective pressure characteristics for individual cycles. Cross-correlation coefficients have been calculated to identify predominant relationships. The effect of combustion phasing on cross-correlation coefficients is particularly significant and three regimes of behaviour have been identified. These are associated with early, optimal and late cases. The cross-correlations between parameters derived from cycle-by-cycle data do not uniformly reflect trends seen between cycle-averaged values of these. Auto-correlation results have been examined for interactions between successive cycles with less success, although, again combustion phasing can have a significant influence on the strength of auto-correlation coefficients.

A physics based, lumped thermal capacity model of a 1litre, 3 cylinder, turbocharged, directly injected spark ignition engine has been developed to investigate the effects of cylinder deactivation on the thermal behaviour and fuel economy of small capacity, 3 cylinder engines. When one is deactivated, the output of the two firing cylinders is increased by 50%. The largest temperature differences resulting from this are between exhaust ports and between the upper parts of liners of the deactivated cylinder and the adjacent firing cylinder. These differences increase with load. The deactivated cylinder liner cools to near-coolant temperature. Temperatures in the lower engine structure show little response to deactivation. Temperature response times following deactivation or reactivation events are similar. Motoring work for the deactivated cylinder is a minor loss; the net benefit of deactivation diminishes with increasing load.

The increased severity and prevalence of insoluble deposits formed on fuel injectors in gasoline direct injection (GDI) engines precipitates negative environmental, economic and healthcare impacts. A necessary step in mitigating deposits is to unravel the molecular compositions of these complex layered materials. But very little molecular data has been acquired. Mass spectrometry shows promise but most techniques require the use of solvents, making them unsuited for analyzing insoluble deposits. Here, we apply the high mass-resolving power and in-situ analysis capabilities of 3D OrbitrapTM secondary ion mass spectrometry (3D OrbiSIMS) to characterize deposits formed on the external tip and internal needle from a GDI injector. This is the first application of the technique to study internal GDI deposits. Polycyclic aromatic hydrocarbons (PAHs) are present up to higher maximum masses in the external deposit.

An experimental investigation has been carried out to compare the indicated performance and heat release characteristics of a DI diesel engine at compression ratios of 18.4:1 and 15.4:1. The compression ratio was changed by modifying the piston bowl volume; the bore and stroke were unchanged, and the swept volume was nominally 500cc. The engine is a single cylinder variant of modern design which meets Euro 4 emissions requirements. Work output and heat release characteristics for the two compression ratios have been compared at an engine speed of 300 rev/min and test temperatures of 10, -10 and -20°C. A more limited comparison has also been made for higher speeds representative of cold idle at one test temperature (-20°C). The reduction in compression ratio generally produces an increase in peak specific indicated work output at low speeds; this is attributable to a reduction in blowby and heat transfer losses and lower peak rates of heat release increasing cumulative burn.

A Ford 2.4-liter 115PS light-duty diesel engine was modified to allow solenoid control of the oil feed to the piston cooling jets, enabling these to be switched on or off on demand. The influence of the jets on piston temperatures, engine thermal state, gaseous emissions and fuel economy has been investigated. With the jets switched off, piston temperatures were measured to be between 23 and 88°C higher. Across a range of speed-load points, switching off the jets increased engine-out emissions of NOx typically by 3%, and reduced emissions of CO by 5-10%. Changes in HC were of the same order and were reductions at most conditions. Fuel consumption increased at low-speed, high-load conditions and decreased at high-speed, low-load conditions. Applying the results to the NEDC drive cycle suggests active on/off control of the jets could reduce engine-out emissions of CO by 6%, at the expense of a 1% increase in NOx, compared to the case when the jets are on continuously.

Two methods of determining the rate of heat transfer from the combustion chamber have been investigated. A First Law analysis is shown to be ill-conditioned because of sensitivity to heat release and gas property calculations. An alternative approach equates cycle-averaged chamber heat transfer to the difference between heat rejected to the coolant and gas heat transfer to the exhaust port. This has been examined as a basis for calibrating the Woschni correlation.

The dilution of lubricating oil by fuel has adverse effects on engine wear, oil lubricity, air/fuel ratio control and feedgas emissions. Dilution is one of the factors limiting oil change intervals. The level and rate of accumulation depend on engine operating conditions and patterns of vehicle use. The work reported here develops and evaluates an empirical model to predict accumulation characteristics. This is aligned to requirements for predictions of dilution build-up in service. Predictions are shown to be in good agreement with data given in the literature. The model is used to investigate the influence of patterns of vehicle use on dilution.

There is a growing demand for composites to be utilised in the production of large-scale components within the aerospace industry. In particular the demand to increase production rates indicates that traditional manual methods are no longer sufficient, and automated solutions must be sought. This typically leads to automated forming processes where there are a limited number of effective options. The need for forming typically arises from the inability of layup methods to produce complex geometries of structural components. This paper reviews the current state of the art in automated forming processes, their limitations and variables that affect performance in the production of large scale components. In particular the paper will focus on the application of force and heat within secondary forming processes. It will then review the effects of these variables against the structure of the required composite component and identify viability of the technology.

Formation of soot is a known phenomenon for diesel engines, however, only recently emerged for gasoline engines with the introduction of direct injection systems. Soot-in-oil samples from a three-cylinder turbocharged gasoline direct injection (GDI) engine have been analysed. The samples were collected from the oil sump after periods of use in predominantly urban driving conditions with start-stop mode activated. Thermogravimetric analysis (TGA) was performed to measure the soot content in the drained oils. Soot deposition rates were similar to previously reported rates for diesel engines, i.e. 1 wt% per 15,000 km, thus indicating a similar importance. Morphology was assessed by transmission electron microscopy (TEM). Images showed fractal agglomerates comprising multiple primary particles with characteristic core-shell nanostructure. Furthermore, large amorphous structures were observed. Primary particle sizes ranged from 12 to 55 nm, with a mean diameter of 30 nm and mode at 31 nm.

Airbus commercial wings are assembled manually in dedicated steel structures. The lead time to design, manufacture and commission these fixtures is often in excess of 24 months. Due to the nature of these fixtures, manufacturing is slow in responding to changes in demand. There is underused capacity in some areas and insufficient ramp-up speed where increased production rate is needed. Reconfigurable Manufacturing Systems and Reconfigurable Assembly Systems (RAS) provide an approach to system design that provides appropriate capacity when needed. The aim of the paper is to review RAS technologies that are suitable for cost-effective wing structure assembly and what knowledge gaps exist for a RAS to be achieved. The paper examines successful cases of RAS and reviews relevant system design approaches. Cost savings are acknowledged and tabularised where demonstrated in research. The research gaps to realising a RAS for wing assembly are identified and different approaches are considered.

The thermal efficiency of an internal combustion engine at steady state temperatures is typically in the region of 25-35%[1]. In a cold start situation, this reduces to be between 10% and 20% [2]. A significant contributor to the reduced efficiency is poor performance by the engine lubricant. Sub optimal viscosity resulting from cold temperatures leads to poor lubrication and a subsequent increase in friction and fuel consumption. Typically, the engine lubricant takes approximately twenty minutes [3] to reach steady state temperatures. Therefore, if the lubricant can reach its steady state operating temperature sooner, the engine's thermal efficiency will be improved. It is hypothesised that, by decoupling the lubricant from the thermal mass of the surrounding engine architecture, it is possible to reduce the thermal energy loss from the lubricant to the surrounding metal structure in the initial stages of warm-up.

Soot formation and distribution inside the cylinder of a light-duty direct injection diesel engine, have been predicted using Kiva-3v CFD software. Pathlines of soot particles traced from specific in-cylinder locations and crank angle instants have been explored using the results for cylinder charge motion predicted by the Kiva-3v code. Pathlines are determined assuming soot particles are massless and follow charge motion. Coagulation and agglomeration have not been taken into account. High rates of soot formation dominate during and just after the injection. Oxidation becomes dominant after the injection has terminated and throughout the power stroke. Computed soot pathlines show that soot particles formed just below the fuel spray axis during the early injection period are more likely to travel to the cylinder wall boundary layer. Soot particles above the fuel spray have lesser tendency to be conveyed to the cylinder wall.

Evolving of aircraft design towards further electrification requires safe and fault-free operation of all the components. More electric aircraft are increasingly utilizing electro-mechanical actuators (EMA). EMAs are prone to jamming and subsequent failure due to large forces on the shaft. Large forces are generated due to the high reflected inertia of the electric machine rotor. To limit the force acting on the shaft, a torque limiting device is connected to the power train which can separate the rotating mass of the electric machine from the power train. In this paper, a concept of integration of torque limiter and the electric machine rotor is presented to reduce overall volume and mass. It is connected closely with the rotor, within the motor envelope. A commercially available torque limiter and an electric machine designed for actuator application are used to demonstrate the concept. While essential for safety, the torque limiter adds to the mass and size of the overall EMA.