Search Results

This study aims to provide an understanding of self-similarity in the turbulent wake generated by a Fastback DrivAer automotive model and assess the impact of upstream disturbances on the wake. The disturbances are generated using a circular cylinder placed five cylinder diameters upstream. Multiple ‘cylinder-model’ positions were tested by offsetting the lateral positioning of the cylinder with respect to the centreline of the model. Data was obtained at cross-planes in the wake going from 25% to 100% car length. Wind tunnel data has been obtained using a total pressure probe rake and a four-hole cobra probe. Data has also been obtained using RANS based simulations with k – ε realisable turbulence model. Mean axial-component velocity profiles were analysed with momentum thickness (θ) and vorticity thickness (δω) used as the scaling parameters. It was seen that self-similarity marginally exists in the wake depending on the upstream conditions and the scaling parameter.

The aim of this paper is to present and discuss a case study on how an Original Equipment Manufacturer's technical design center translates and integrates legislative environmental requirements into their product range. The integration of these environmental requirements during the conceptual design phase, where the significant proportion of resources is committed, is of utmost importance. Additionally, with increasing levels of product development being conducted by the first-tier suppliers, there is greater emphasis on the Original Equipment Manufacturer, who controls the product specifications, for translating and filtering the environmental requirements down the supply chain. A Requirements Management based model addressing environmental issues is described.

The effect of local fuel concentration on cyclic variability in combustion and engine performance in a lean burn stratified charge engine has been investigated. The fuel concentration in a plane close to the spark plug was measured for a large number of cycles using laser-induced fluorescence (LIF) and simultaneous measurement of in-cylinder pressure in an one-cylinder optical research engine. It could be shown quantitatively that the fuel concentration in a small region close to the spark plug has a dominating effect on the subsequent pressure development for lean mixtures. Variations in the mixture concentration in the vicinity of the spark plug contribute significantly to cyclic variation in combustion. Measurement of the flame area in the same plane 20 °CA after ignition revealed that the direction of growth of the established flame is not significantly influenced by the stoichiometry.

The manufacturing cost of composite aerostructures is considerably higher than that of equivalent light-alloy ones. There are several reasons for this, but the transfer of the existing technology from military to civil aviation is identified as a major problem. Neither the designs, nor the methods of manufacture, are considered cost-effective when applied to very large, commercially competitive, structures. This problem was among those addressed within a multi-disciplinary, concurrent engineering project sponsored by BAe Airbus and the UK DTI. During the four year programme, alternative manufacturing technology was developed, and Pilot-plant equipment built. The Pilot-plant was successfully used to demonstrate that wing-box components can be more cheaply, more reliably, and more easily manufactured by simple, innovative, easily automated processes.

This paper describes work being conducted by OC Robotics and Airbus to develop snake-arm robots to conduct assembly tasks within wing boxes - an area currently inaccessible for automation. The composite, single skin construction of aircraft structures presents new assembly challenges. Currently during box close-out it is necessary for aircraft fitters to climb into the wing box through small access panels and use manual or power tools to perform a variety of tasks. In future wing designs it may be that certain parts of the wing do not provide adequate access for manual assembly methods. It is also known that these manual interventions introduce health and safety concerns with their associated costs. Snake-arm robots provide a means to replace manual procedures by delivering the required tools to all areas of the wing box. Such a development has broader implications for aircraft design and assembly.

This paper describes work being conducted by OC Robotics and Airbus to develop snake-arm robot technology suitable for conducting automated inspection and assembly tasks within wing boxes. The composite, single skin construction of aircraft structures presents new challenges for robotic assembly. During box close-out it is necessary for aircraft fitters to climb into the wing box through a small access panel and use manual or power tools to perform a variety of tasks. These manual interventions give rise to a number of health and safety concerns. Snake-arm robots provide a means to replace manual procedures by delivering the required tools to all areas of the wing box. The advantages of automating in-wing processes will be discussed. This paper presents early stage results of the demonstration snake-arm robot and outlines expectations for future development.

A new method of installing LGP collars onto titanium lock bolts has been brought into production in the Airbus wing manufacturing facility in Broughton, Wales. The feed system involves transporting the collar down a rectangular cross-sectioned hose, through a rectangular pathway in the machine clamp anvil to the swage die without the use of fingers or grippers. This method allows the reliable feeding the collars without needing to adjust the position of feed fingers or grippers relative to the tool centerline. Also, more than one fastener diameter can be fed through one anvil geometry, requiring only a die change to switch between certain fastener diameters. In our application, offset and straight stringer geometries are accommodated by the same anvil.

This paper gives an overview of the development of a number of loss models for the pushing metal V-belt CVT. These were validated using a range of experimental data collected from two test rigs. There are several contributions to the torque losses and new models have been developed that are based upon relative motion between belt components and pulley deflections. Belt slip models will be proposed based upon published theory, expanded to take account of new findings from this work. The paper introduces a number of proposals to improve the efficiency of the transmission based on redesign of the belt geometry and other techniques to reduce frictional losses between components. These proposed efficiency improvements have been modelled and substituted into a complete vehicle simulation to show improvements in vehicle fuel economy over a standard European drive cycle.

The first cross-industry guidelines for the implementation of structural health monitoring for aerospace applications have been created as a SAE International Aerospace Recommended Practices document: SAE ARP 6461 ‘Guidelines for Implementation of Structural Health Monitoring on Fixed Wing Aircraft’ [1]. These guidelines have brought together manufacturers, operators / users, systems integrators, regulators, technology providers and researchers to produce information on the integration of SHM into aircraft maintenance procedures, generic requirements and advice on validation, verification and airworthiness. The take-up of SHM in the aerospace industry has been slow, in part due to the lack of accepted industry practices surrounding not just the technology itself (sensors and sensor systems) but also the associated issues arising from the introduction of new methods into aircraft maintenance.

This paper will present the latest development of a configurable and modular steel construction system for use in frameworks of flexible fixtures of the kind called Affordable Reconfigurable Fixtures (ART). Instead of a dedicated aircraft fixture, which is very time consuming and expensive, the ART fixtures enable affordable construction from a standard component kit, by solving the main drawbacks of traditional tooling. In early 2009 Airbus UK built the first steel modular fixture for the aerospace industry. The project was a partnership with DELFOi and Linköping University in a project called ReFlex, Reconfigurable Flexible Tooling. A paper was presented in the last year SAE conference which explained about the project in overall. The construction system called BoxJoint has recently been tested in some manufacturing areas at Airbus UK and also been applied in the production at Saab Aerospace Linköping Sweden.

The present work focuses on developing an integrated airframe, distributed propulsion, and power management methodology for liquid-hydrogen-fuelled HALE UAVs. Differently from previous studies, the aim is to assess how the synergies between the aforementioned sub-systems affect the integrated system power requirement, production, and distribution. A design space exploration study was carried out to assess the influence of distributing motor-driven fans on three different airframes, namely a tube-and-wing, a triple-fuselage, and a blended-wing-body. For the considered range of take-off masses from 5,000 to 15,000 kg, the 200 kW payload power requirement under examination was found to re-shape the endurance trends. In fact, the drop in specific fuel consumption due to the engine design point change alters the trends from nearly flat to a 25% maximum endurance increase when moving towards heavier take-off masses.

A mild hybrid powertrain with crankshaft mounted integrated motor generator (IMG) and torque controlled infinitely variable transmission (IVT) has shown clear potential for fuel economy (FE) enhancement. It also makes significant driveability and performance improvements possible which are a condition for customer satisfaction and subsequent marketability. The hybrid powertrain supervisory control strategy presented here uses the energy recovered during braking events for power assist, hence improving FE and driveability compromises. This is achieved by operating the engine at its best brake specific fuel consumption (BSFC) point during steady state conditions without deteriorating the transient response as a result of the comparatively fast IMG torque response. This paper demonstrates the launch manoeuvre and general driveability improvements achieved in simulation with validated models.

In today's aircraft the diagnostic and prognostic systems play a crucial part in aircraft safety while reducing the operating and maintenance costs. Aircraft are very complex in their design and require consistent monitoring of systems to establish the overall vehicle health status. Most diagnostic systems utilize advanced algorithms (e.g. Bayesian belief networks or neural networks) which usually operate at system or sub-system level. The sub-system reasoners collect the input from components and sensors to process the data and provide the diagnostic/detection results to the flight advisory unit. Several sources of information must be taken into account when assessing the vehicle health, to accurately identify the health state in real time. These sources of information are independent system-level diagnostics that do not exchange any information/data with the surrounding systems.

This paper details the development of a user-friendly computerised tool created to evaluate the Manufacturing Readiness Levels (MRL) of an emerging technology. The main benefits achieved are to manage technology development planning and tracking, make visually clear and standardised analysis, and improve team communication. The new approach is applied to the Technology Readiness Levels (TRL), currently used by Airbus Research & Technology (R&T) UK. The main focus is on the improvement of the analysis criteria. The first phase of the study was to interpret the manufacturing criteria used by Airbus at TRL 4, including a brief benchmarking review of similar practices in industry and other Airbus' project management tools. All information gathered contributed to the creation of a complete set of criteria.

Simulations are presented which fully couple both the aerodynamics and cooling flow for a model of a fully engineered production saloon car (Jaguar XJ) with a two-tier cooling pack. This allows for the investigation of the overall aerodynamic impact of the under-hood cooling flow, which is difficult to predict experimentally. The simulations use a 100 million-element mesh, surface wrapped and solved to convergence using a commercially available RANS solver (STARCCM+). The methodology employs representative boundary conditions, such as rotating wheels and a moving ground plane. A review is provided of the effect of cooling flows on the vehicle aerodynamics, compared to published data, which suggest cooling flow accounts for 26 drag counts (0.026 Cd). Further, a sensitivity analysis of the pressure drop curves used in the porous media model of the heat exchangers is made, allowing for an initial understanding of the effect on the overall aerodynamics.

Co-production of aircraft is resulting in demands for higher standards of manufacturing quality to ensure that parts and sub-assemblies from different companies and countries are compatible and interchangeable. As a result the existing method of building aerostructure using large numbers of dedicated manufacturing jigs and assembly tools, is now seen as being commercially undesirable, and technologically flawed. This paper considers an alternative, potentially more cost-effective, approach that embraces digital design, manufacturing, and inspection techniques, and in which reference and tooling features are incorporated into the geometry of the component parts. Within the aerospace industry this technology is known as ‘Flyaway Tooling’.

Current modelling capability for engine icing accretion prediction is still limited for App. C. To further validate icing codes in complex engine geometries, it is necessary to perform additional experimental work in relevant geometrical and environmental conditions. Within the frame of ICE GENESIS [1], an experiment has been setup to replicate the condition at the inlet of an engine first stage compressor. This paper describes the choices for the design of the engine compressor model, the setup within the icing wind tunnel and the methodology employed to obtain the results. Additionally, more effort has been focused on obtaining accurate ice shapes using a 3D scanning system. Results of 3D scans are given.

UAS (Unmanned aircraft system), widely known to the general public as drones, are comprised of two major system elements: an Unmanned Aircraft (UA) and a Ground Control Station (GCS). UAS have a high mishap rate when compared to manned aircraft. This high mishap rate is one of several barriers to the acceptance of UAS for more widespread usage. Better awareness of the UA real time as well as long term health situation may allow timely condition based maintenance. Vehicle health and usage are two parts of the same solution to improve vehicle safety and lifecycle costs. These can be worked on through the use of two related aircraft management methods, these are: IVHM (Integrated Vehicle Health Management) which combines diagnosis and prognosis methods to help manage aircraft health and maintenance, and FOQA (Flight Operations Quality Assurance) systems which are mainly used to assist in pilot skill quality assurance.

The paper describes a way of generating a cost model, which is aimed to compare different drilling processes. The development of this tool is a part of an ongoing European Union funded aircraft industry project called ADFAST (Automation for Drilling, Fastening, Assembly, Systems Integration, and Tooling). This part of the project involves 4 industrial partners, (Alenia, Airbus Espana SL, Airbus UK and Saab AB), 1 equipment developer (Novator AB) and 1 academic institute (Linkoping University). The model has been created to enable the benefits of an advanced system such as orbital drilling to be quantified. The model is able to generate a cycle time and a cost for the whole drilling process involving equipment, consumables and assembly of varied aircraft structures. The challenge of the task was to develop the ability of modeling a process with a sequence of drilling operations that the model user, in an intuitive way, can select and modify.

Jigless assembly is an approach towards reducing the cost and increasing the flexibility of tooling systems for aircraft manufacture through the minimisation of productspecific jigs, fixtures and tooling. A new, integrated methodology has been developed, which uses a number of building blocks and tools, to enable design for jigless assembly as a result of a logical, step-by-step process. This methodology, AIM-FOR-JAM, is currently being applied to redesign the Airbus A320 Fixed Leading Edge for jigless assembly, as part of the ‘Jigless Aerospace Manufacture’ (JAM) project.