Transonic and supersonic ground effect aerodynamics

A review of recent and historical work in the field of transonic and supersonic ground effect aerodynamics has been conducted, focussing on applied research on wings and aircraft, present and future ground transportation, projectiles, rocket sleds and other related bodies which travel in close ground proximity in the compressible regime. Methods for ground testing are described and evaluated, noting that wind tunnel testing is best performed with a symmetry model in the absence of a moving ground; sled or rail testing is ultimately preferable, though considerably more expensive. Findings are reported on shock-related ground influence on aerodynamic forces and moments in and accelerating through the transonic regime – where force reversals and the early onset of local supersonic flow is prevalent – as well as more predictable behaviours in fully supersonic to hypersonic ground effect flows

A study of the factors that influence the perceptions of strategic information value in major UK based organisations

It has been argued for many years that if applied effectively, information can be a valuable organisational resource; indeed, many contend that it is the lifeblood of the organisation. This view is supported by the academic literature, which identifies a wide range of factors that influence perceptions of strategic information value. For example, information quality and information accessibility have both been widely discussed. The use of information for enabling organisational change in organisations, for marketing activities, and for strategic planning have also been the subject of academic investigation. However, whilst the literature in this domain is fairly extensive, it is largely theoretical, rather than empirical, in nature and it also tends to be highly fragmented, addressing narrow aspects of value. The primary aim of this study was to undertake a holistic exploration of the factors affecting the perceived value of strategic information, using rigorous empirical methods. Moreover, the research sought to address the question of why organisations typically fail to treat information as a formal asset, even though they perceive it to be valuable resource. To explore these broad objectives, a three-phase approach was adopted combining the use of both quantitative and qualitative methods of research. More specifically, the study commenced with a questionnaire-based survey that was designed to validate the initial conceptual framework. This was followed by a phase of the research, which utilised detailed case studies in eight major UK based commercial organisations, to explore how perceptions of information value were affected by the implementation of data warehouses. The final phase of the study sought to validate the research findings and explore their wider implications, through the utilisation of on-line focus groups. The research project has produced several key findings. It has provided evidence that information accessibility and information quality are critical constructs that impact the perceived value of information. It has confirmed that a number of business activities, such as marketing, are highly dependent on the use of information. It has suggested that improvements in the accessibility and quality of information can lead to the improved effectiveness of these business activities, and that this can lead to the attainment of more substantial measurable business benefits. Finally, the research has also suggested that although most organisations consider information to be valuable, few give serious consideration to formally classing information as an asset, and none appear to measure the value of their information assets. It is believed that this study has made a number of significant contributions to the literature. It has provided a holistic view of the dimensions that can impact the perceived value of strategic information. Most importantly, from an academic perspective, it has produced empirically based evidence on the relationships between a wide-range of dimensions and the perceived value of information, on attitudes to information being considered an asset, and the actions organisations take to measure the value of information assets. It has been argued that without a clear understanding of the value of information, it is difficult to manage it appropriately, and consequently it is also difficult to ultimately attain the value of the information. By providing afar clearer and holistic picture of the factors affecting the value of information, coupled with many important new insights about the management of information, the results of this study should help to ensure that organisations can fully realise the value of their strategic information resources

Application of kriging to motorsport aerodynamic analysis

Aerodynamic analysis in motorsport is conducted using three methods, computational, scaled experimental and full-scale operational. However, the varying fidelity, different sampling resolutions and unavoidable errors of each technique make valid comparisons between datasets from each method difficult and time consuming. Kriging is a geostatistical method to estimate values within a data field by examining and applying the trends of the dataset. This research examines how such techniques can be used to aid comparison between aerodynamic measurements of a race car. It examines how kriging can be used to transform discrete measurements, of varying fidelity and sampling resolution, into semi-continuous measurements, thus allowing computational results to be compared across a wider range of conditions than initially tested. This work explores how kriging can allow the trends from highly sampled data, such as track running, to be applied to less sampled data, such as CFD to improve computational and overall aerodynamic analysis

Aerodynamic testing and development of Sunswift eVe

The current understanding of the aerodynamic performance of Sunswift’s solar-electric race car eVe is limited, despite the design and manufacture of the vehicle in 2012-13. This paper describes an investigation into the aerodynamic behaviour of the vehicle and details the successive design and development of drag minimisation strategies. A study of the ex­ternal airflow around the vehicle was undertaken through a computational fluid dynamics analysis, with validation offered through the results of real-world track testing. Particular reference is made to the Sunswift team’s successful long-range electric vehicle land speed record attempt on 23 July 2014. A predicted 10% reduction in drag has been achieved through external bodywork modifications as described within this paper. Recommenda­tions for the design of low drag vehicles are also presented, with relation made to the future of sustainable transport

Fundamental Studies of Vortices Induced by a Vortex-generator for Automotive Applications

For automotive applications, passive flow control devices can be used to reduce, delay or prevent flow separation. This study explores the nature of vortex generation and behaviour, numerically and experimentally, for a simple geometry at a Reynolds Number (Rex) of 5×105 and 1.945×106. The setup comprised a triangular vane vortex-generator mounted on a shallow ramp referenced from literature. Flow over the isolated ramp was validated with past experimental particle-image-velocimetry (PIV) data, which also highlighted the relative performance of various turbulence models. A parametric study was undertaken with the vane orientation defined by an angle-of-attack (β) and stream-wise location (xedge/xVG). These results revealed relationships between geometric parameters of the vortex generator, as well as the influence of the boundary layer thickness (hVG/δ), on the spatial trajectory of induced vortices

Aerodynamic design and development of the Sunswift IV solar racing car

The aerodynamic design and development of the University of New South Wales\u27 ultra-low-drag solar-electric Sunswitt IV car is described, detailing the student-led design process from initial concept sketches to the completed vehicle. The body shape was established and relined over a period of six months in 2008-2009, almost entirely using computational fluid dynamics. The guiding philosophy was that predictable handling and drag minimization in challenging, changing wind conditions of the type commonly seen during the World Solar Challenge across Australia was preferable to high performance only on \u27perfect\u27 days. The car won its class in the 2009 and 2011 World Solar Challenges, and holds the Guinness World Record for last est solar-powered vehicle

The effects of simplifications on isolated wheel aerodynamics

In order to study the aerodynamic forces and flow features of rotating wheels, compromises and simplifications are often made in wind tunnel testing, and more frequently so in numerical modelling. A CFD approach similar to that commonly used in industry was utilised to investigate common assumptions involving; the influence of geometric fidelity in wheel hub regions, ground representation, the modelling of the contact patch, and the effects of rotation on separation. It was found that the separation and wake characteristics were strongly influenced by the rotation of the wheel; the separation point changed by as much as 90% compared to a stationary wheel, and drag was close to 20% less – downforce was approximately 40% greater. In addition, the modelling of the contact patch, treated here as a small step to facilitate skew-free meshing necessary for a reliable converged result, was seen to cause up to a 52% difference in predicted lift characteristics, and an increase in the step of just 2 mm decreased the maximum wake thickness by close to 50% – considerable changes stemming from superficially-minor simplifications. Including indented wheel hubs proved to be more influential on the production of vortices and wake structures, causing the merging of previously-separate vortex structures. The results point to a need for very careful evaluation of the goals of any study when determining which simplifications can be made in both physical testing and numerical analysis

Design of high-area-ratio nozzle contours using circular arcs

A method using circular arcs to generate the divergence contour in a supersonic nozzle is presented. Comparison of the arc-based geometry with existing nozzle contours demonstrated that an average decrease in axial length of 7.5% can be expected when the arc-based design method is applied to a core stage nozzle. Two arc-based and conventional nozzles were evaluated numerically across the pressure operating range of a core stage engine to compare calculated thrust and separation characteristics with existing data. The length-weighted thrust coefficient was increased by 0.3–1.8% in the arc-based design in both configurations. Separated flow characteristics were compared using contours of Mach number and static pressure distributions, which suggested equivalent side loading in the arc-based nozzle at separated flow conditions. The result indicates that a geometric advantage independent of thrust may be achieved when the arc-based method is applied to high-area-ratio nozzle contour design