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Technical Paper

Assessing the Accuracy of Soot Nanoparticle Morphology Measurements Using Three-Dimensional Electron Tomography

2019-04-02
2019-01-1188
Morphology plays an important role in determining behaviour and impact of soot nanoparticles, including effect on human health, atmospheric optical properties, contribution to engine wear, and role in marine ecology. However, its nanoscopic size has limited the ability to directly measure useful morphological parameters such as surface area and effective volume. Recently, 3D morphology characterization of soot nanoparticles via electron tomography has been the subject of several introductory studies. So-called ‘3D-TEM’ has been posited as an improvement over traditional 2D-TEM characterization due to the elimination of the error-inducing information gap that exists between 3-dimensional soot structures and 2-dimensional TEM projections. Little follow-up work has been performed due to difficulties with developing methodologies into robust high-throughput techniques.
Journal Article

The Application of New Approaches to the Analysis of Deposits from the Jet Fuel Thermal Oxidation Tester (JFTOT)

2017-10-08
2017-01-2293
Studies of diesel system deposits continue to be the subject of interest and publications worldwide. The introduction of high pressure common rail systems resulting in high fuel temperatures in the system with the concomitant use of fuels of varying solubilizing ability (e.g. ULSD and FAME blends) have seen deposits formed at the tip of the injector and on various internal injector components. Though deposit control additives (DCAs) have been successfully deployed to mitigate the deposit formation, work is still required to understand the nature and composition of these deposits. The study of both tip and internal diesel injector deposits (IDID) has seen the development of a number of bench techniques in an attempt to mimic field injector deposits in the laboratory. One of the most used of these is the Jet Fuel Thermal Oxidation Tester or JFTOT (ASTM D3241).
Journal Article

Evaluation of Control Methods for Thermal Roll Forming of Aerospace Composite Materials.

2016-09-27
2016-01-2118
With increased demand for composite materials in the aerospace sector there is a requirement for the development of manufacturing processes that enable larger and more complex geometries, whilst ensuring that the functionality and specific properties of the component are maintained. To achieve this, methods such as thermal roll forming are being considered. This method is relatively new to composite forming in the aerospace field, and as such there are currently issues with the formation of part defects during manufacture. Previous work has shown that precise control of the force applied to the composite surface during forming has the potential to prevent the formation of wrinkle defects. In this paper the development of various control strategies that can robustly adapt to different complex geometries are presented and compared within simulated and small scale experimental environments, on varying surface profiles.
Journal Article

Technology Review of Thermal Forming Techniques for use in Composite Component Manufacture

2015-09-15
2015-01-2610
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.
Technical Paper

Permanent Magnet Starter-Generator for Aircraft Application

2014-09-16
2014-01-2157
This paper describes a high-speed electrical machine for an aircraft starter-generator. A surface mounted permanent magnet machine is designed to have minimal rotor losses and a novel cooling system for the stator. An inner stator sleeve is adopted to allow for a flooded stator whilst minimizing rotor windage losses. Different slot-pole combinations are compared in view of attaining an optimal combination that provides minimum losses whilst satisfying the electromagnetic, mechanical and thermal constraints.
Technical Paper

Control Design for Electric Starter-Generator Based on a High-Speed Permanent-Magnet Machine Fed by an Active Front-End Rectifier

2014-09-16
2014-01-2139
The paper reports the control design for an aircraft electric starter-generator system based-on high-speed permanent magnet machine operated in a flux-weakening mode and controlled by an active front-end rectifier. The proposed system utilizes advances of modern power electronics allowing the use of novel machine types and the introduction of controlled power electronics into the main path of energy flow. The paper focuses on control design for such system and includes development of flux weakening control of high-speed permanent magnet machine and droop control of the system output dc-link current. The achieved analytical design results and the expected system performance are confirmed by time-domain simulations.
Technical Paper

Reducing Energy Losses from Automotive Engine Lubricants by Thermal Isolation of the Engine Mass

2014-04-01
2014-01-0672
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.
Technical Paper

Investigating the Effect of Carbon Nanoparticles on the Viscosity of Lubricant Oil from Light Duty Automotive Diesel Engines

2014-04-01
2014-01-1481
The influence of size and concentration of carbon nanoparticle on the viscosity of an SAE 5W-30 lubricant oil has been investigated experimentally. Data were collected for oil samples drawn from sump of light duty automotive diesel engines. The average size of soot particles in the used oil samples was in the range of 180-320nm with concentrations ranging from 0 to 2 percentage by weight (wt. %.). A Brookfield DV-II Pro rotary viscometer was used to measure dynamic viscosity at low shear rates and temperatures of 40°C and 90°C. Nanoparticle concentration and particle size distribution were evaluated using Thermo-Gravimetric Analysis (TGA) and Dynamic Light Scattering (DLS) respectively. The viscosity of suspensions of graphite powder in lubricant oil was also investigated for concentrations ranging from 0 to 2 wt. %. The results show that dynamic viscosity increases with increasing soot content and decreasing temperature.
Journal Article

Emerging Technologies for Use in Aerospace Bonded Assemblies

2013-09-17
2013-01-2134
Several new technologies are now emerging to improve adhesive supply and formulation along with surface treatments that have the potential to offer significant improvements to both surface energy and cleanliness [3]. Additionally, the miniaturisation of laboratory techniques into portable equipment offers potential for online surface energy and chemical analysis measurement for use as quality control measures in a production environment. An overview of newly available technology is given here with several devices studied in further detail. Technologies assessed further in this paper are; portable surface contact angle measurement, ambient pressure plasma cleaning, portable FTIR measurement and adhesive mixing equipment. A number of potential applications are outlined for each device based on the operational technique. The practical aspects of implementation and the perceived technology readiness levels for operation, implementation and results are also given.
Technical Paper

Review of Reconfigurable Assembly Systems Technologies for Cost Effective Wing Structure Assembly

2013-09-17
2013-01-2336
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.
Technical Paper

Fixturing and Tooling for Wing Assembly with Reconfigurable Datum System Pickup

2011-10-18
2011-01-2556
The aerospace manufacturing sector is continuously seeking automation due to increased demand for the next generation single-isle aircraft. In order to reduce weight and fuel consumption aircraft manufacturers have increasingly started to use more composites as part of the structure. The manufacture and assembly of composites poses different constraints and challenges compared to the more traditional aircraft build consisting of metal components. In order to overcome these problems and to achieve the desired production rate existing manufacturing technologies have to be improved. New technologies and build concepts have to be developed in order to achieve the rate and ramp up of production and cost saving. This paper investigates how to achieve the rib hole key characteristic (KC) in a composite wing box assembly process. When the rib hole KC is out of tolerances, possibly, the KC can be achieved by imposing it by means of adjustable tooling and fixturing elements.
Journal Article

The Potential for Fibre Alignment in the Manufacture of Polymer Composites from Recycled Carbon Fibre

2009-11-10
2009-01-3237
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.
Technical Paper

The Build-Up of Oil Dilution by Gasoline and the Influence of Vehicle Usage Pattern

2000-10-16
2000-01-2838
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.
Technical Paper

The Influence of Gas/Fuel Ratio on Combustion Stability and Misfire Limits of Spark Ignition Engines

2000-03-06
2000-01-1208
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.
Technical Paper

Audit of Fuel Utilisation During the Warm-Up of SI Engines

1997-05-01
971656
Experimental studies of fuel utilisation during the early stages of engine warm-up after cold-starts are reported. The investigation has been carried out on a 1.81, 4 cylinder spark-ignition engine with port electronic fuel injection. The relationship between fuel supplied and fuel accounted for by the analysis of exhaust gas composition shows that a significant mass of fuel supplied is temporarily stored or permanently lost. An interpretation of data is made which allows time-dependent variations of these to be separately resolved and estimates of fuel quantities made. The data covers a range of cold-start conditions down to -5°C at which, on a per cylinder basis, fuel stored peaks typically at around 0.75g and a total of 1g is returned over 100 seconds of engine running. Fuel lost past the piston typically accounts for 2g over 200 to 300 seconds of running.
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