Experimental investigation of the effect of coherent secondary structures upon a tip vortex
Lead Research Organisation:
University of Surrey
Department Name: Mechanical Medical and Aerospace Eng
Abstract
A vortex occurs when some of the fluid within a larger volume is caused to rotate, and is one of the most important phenomena in fluid mechanics. Vortices may range in size from microns (such as those formed around the beating wings of a mosquito) to hundreds of kilometers (such as hurricanes), and are of great importance in a large number of engineering applications. Vortex flows are of particular interest in the aircraft industry, since part of an aircraft's drag is the result of the formation of large vortices by the wing tips. As the engines propel the aircraft forward, part of the engine power is used to no other benefit than stirring the air behind the aircraft. If the wing tip vortex could be reduced in strength, the aircraft drag would decrease, reducing the amount of fuel burned. This would lead to both decreased carbon emissions and operating costs. The large vortices in the aircraft wake also pose a danger to other aircraft, so a minimum distance must be kept between them. Since the vortices are strongest at low speed such as during takeoff and landing, this wake hazard is what limits runway capacity. If the vortex could be destabilized and forced to break up and dissipate more quickly, airports would be able to accommodate a larger number of flights without needing additional runways. The strength and stability of a wing-tip vortex can be greatly reduced by introducing turbulence (or random disturbances) into the flow ahead of the wing. These disturbances interact with the vortex, transport energy away from it and reduce its strength. However, in wind tunnel tests, the disturbances are usually introduced by placing a series of heavy bars ahead of the wing; on a real aircraft, this would not be possible. Instead, in this study, small and carefully designed 'bumps' will be strategically placed on the surface of the wing in order to generate similar disturbances.Since there are infinitely many possible combinations of bump geometries and locations, it is first necessary to study the vortex and how it is affected by smaller disturbances. To begin with, despite the engineering importance of these flows, it still isn't clear whether or not there are naturally-occurring disturbances inside a vortex. Also, vortices are in many ways analogous to the flow over flat walls. Though similar disturbances occur naturally in wall flows and play a vital role in their development, very little attention has been given to the role played by the disturbances in vortex flows. If it can be shown that very small disturbances can have an effect on large vortices, this in itself would be an extremely important result: many flow simulation computer codes assume that the direct interaction between very small disturbances and very large vortices is impossible. Finally, all vortices- regardless of how they were generated, how strong they are or how 'disturbed' they may be- appear to evolve in exactly the same way. While this similarity has already been noticed, it is still not clear why it happens. Once the vortex and the way it responds to disturbances is better understood, this understanding will be used to intelligently develop a wing surface which can reduce aircraft drag (cutting down both cost and carbon emissions) and increase airport capacity.
Planned Impact
The results of the proposed study would be of significant interest to aircraft manufacturers and operators. Any drag reduction would translate directly to fuel savings and an improvement in operating efficiency, as well as a reduction in carbon emissions. Furthermore, the proposed study would also be of interest to airport operators, as a reduction in wake hazard would increase airport capacity without the need for additional runways, which would allow the continued expansion of commercial air traffic with minimal disruption to nearby communities. The applications of this research will also not be limited to aircraft. Road vehicles also expend energy in the production of unwanted vortices, so an inexpensive and simple vortex control technology could improve road vehicle fuel efficiency and reduce ground-level emissions (based on 1997 fuel consumption data, a 0.1% average decrease in passenger car drag would have resulted in an overall savings of over 10 million litres of petrol and diesel in the UK alone). The understanding and technology developed would be applicable within the chemical processing industry as well, where vortex generators of various types are used to promote mixing. By applying the technology developed to these vortex generators, the rate of turbulent transport will be increased, leading to the refinement of the design of reaction and mixing vessels. The fundamental results of the proposed study will also be of value to developers of commercial large-eddy flow simulation codes, as a flow field database would be generated in which the interactions between structures of carefully controlled sizes are catalogued. The database could be used for the refinement and improvement of the modelling, as LES codes have difficulty accurately representing the direct interactions of very small structures with very large structures. This research will generate a bankable technology, and the patentability and marketing of the technology will be explored in conjunction with the University of Surrey Research and Enterprise Support Office, as the University of Surrey as strong links within the commercial defence technology, aerospace and automotive industries. For maximum exposure, the scientific results will be disseminated through publication in highly circulated peer-reviewed scientific journals, including the Journal of Aircraft, the Journal of Fluid Mechanics and the AIAA Journal. Summaries of progress and interim results will be made publicly available on the University of Surrey website, and results will be presented at European and international conferences with both academic and industrial attendance (such as the AIAA, ETC and APS/DFD meetings, as well as any future UKTC meetings) for maximum exposure. The University of Surrey also strongly supports community awareness and engagement activities (such as its annual Science Circus for local children). The student will be encouraged to participate in these activities and will be provided with any necessary training or support.
People |
ORCID iD |
David Birch (Principal Investigator) |
Publications
Birch D
(2013)
Tracer particle momentum effects in vortex flows
in Journal of Fluid Mechanics
Birch D
(2012)
Self-similarity of trailing vortices
in Physics of Fluids
Jammy S
(2014)
Boundary conditions and vortex wandering
in Journal of Fluid Mechanics
McParlin, S.
(2013)
Optimal calibration of directional velocity probes
Shaw-Ward S
(2018)
Optimal Calibration of Directional Velocity Probes
in AIAA Journal
Shaw-Ward S
(2015)
Calibration and Use of n-Hole Velocity Probes
in AIAA Journal
Description | In addition to generating some useful insight into the behaviour of vortical flows, the novel instrumentation which we developed in order to carry out this work itself has sparked off new research, collaborations, patents, and even a spin-out company- none of which would have been predictable at the time of application. |
Exploitation Route | This is still being explored. |
Sectors | Aerospace, Defence and Marine,Environment,Healthcare,Pharmaceuticals and Medical Biotechnology,Other |
URL | http://www.surrey.ac.uk/mes/people/david_birch/ |
Description | As a primarily fundamental study, the results of this work have contributed in a wide range of areas. The experimental instrumentation developed, in their own right, represented an important step forward; one of the instruments used has developed into a medical diagnostic device, for which a patent application has been submitted. The technology and capability that enabled the development of these instruments has also resulted in the formation of a new university start-up company, and a new collaborative partnership with health professionals. Several important papers have been produced in the areas of fluid physics, computational fluid dynamics and measurement technology. An application to atmospheric science, and an important partnership with colleagues working in air quality and dispersion has also emerged from this research project. |
First Year Of Impact | 2012 |
Sector | Aerospace, Defence and Marine,Agriculture, Food and Drink,Environment,Healthcare,Other |
Impact Types | Economic |
Description | EPSRC Impact Acceleration Account (IAA) |
Amount | £20,000 (GBP) |
Organisation | University of Surrey |
Sector | Academic/University |
Country | United Kingdom |
Start | 04/2014 |
Description | EPSRC Impact Acceleration Account (IAA) |
Amount | £19,200 (GBP) |
Organisation | University of Surrey |
Sector | Academic/University |
Country | United Kingdom |
Start | 10/2016 |
End | 02/2017 |
Description | Development of a fast respirometer |
Organisation | South-East Health Technology Alliance |
Country | United Kingdom |
Sector | Private |
PI Contribution | Development of a high-sensitivity respirometer for medical and clinical applications |
Collaborator Contribution | Market analysis and pre-clinical testing of the instrument |
Impact | None yet |
Start Year | 2014 |
Description | Impact of aircraft vortex wakes on air quality near large airports |
Organisation | King's College London |
Country | United Kingdom |
Sector | Academic/University |
PI Contribution | This was an unexpected outcome of the particle modelling carried out for this project; a need for this sort of modelling had been previously and independently identified within the air quality and emissions community. A collaborative funding bid is currently underway. The report of the tehchnical committee on the Project for the Sustainable Development of Heathrow (2006) has identified the importance of establishing the role of aircraft wakes in the dispersion of gaseous and particulate emissions in the vicinity of airports. A collaboration between aircraft aerodynamicists and air quality modellers is therefore of significant importance toward this end. |
Collaborator Contribution | The University of Surrey Department of Civil Engineering is contributing expertise in the modelling of air quality. King's College London is contributing expertise in environmental monitoring and field measurements. A joint NERC bid is currently in submission, awaiting outcome. |
Impact | None yet. |
Start Year | 2013 |
Description | Impact of aircraft vortex wakes on air quality near large airports |
Organisation | University of Surrey |
Country | United Kingdom |
Sector | Academic/University |
PI Contribution | This was an unexpected outcome of the particle modelling carried out for this project; a need for this sort of modelling had been previously and independently identified within the air quality and emissions community. A collaborative funding bid is currently underway. The report of the tehchnical committee on the Project for the Sustainable Development of Heathrow (2006) has identified the importance of establishing the role of aircraft wakes in the dispersion of gaseous and particulate emissions in the vicinity of airports. A collaboration between aircraft aerodynamicists and air quality modellers is therefore of significant importance toward this end. |
Collaborator Contribution | The University of Surrey Department of Civil Engineering is contributing expertise in the modelling of air quality. King's College London is contributing expertise in environmental monitoring and field measurements. A joint NERC bid is currently in submission, awaiting outcome. |
Impact | None yet. |
Start Year | 2013 |
Description | Turbulence in fractal internal flows for pneumopathological assessment |
Organisation | Imperial College London |
Department | National Heart & Lung Institute (NHLI) |
Country | United Kingdom |
Sector | Academic/University |
PI Contribution | Imperial College is contributing expertise in flow simulation/DNS and in the multifractal nature of turbulence; King's College is contributing expertise in human respiratory anatomy and disease; I am contributing expertise in turbulent flow measurement and instrumentation development. |
Collaborator Contribution | We have developed a strong, multidisciplinary research proposal and are now trying to collect some pilot data to support this. |
Impact | This is a multidisciplinary collaboration. No outputs have yet been published. |
Start Year | 2016 |
Description | Turbulence in fractal internal flows for pneumopathological assessment |
Organisation | King's College London |
Department | Department of Physics |
Country | United Kingdom |
Sector | Academic/University |
PI Contribution | Imperial College is contributing expertise in flow simulation/DNS and in the multifractal nature of turbulence; King's College is contributing expertise in human respiratory anatomy and disease; I am contributing expertise in turbulent flow measurement and instrumentation development. |
Collaborator Contribution | We have developed a strong, multidisciplinary research proposal and are now trying to collect some pilot data to support this. |
Impact | This is a multidisciplinary collaboration. No outputs have yet been published. |
Start Year | 2016 |
Title | "A flow meter" |
Description | This is a compact, very-high-sensitivity, time-accurate flow meter intended for use in medical diagnostics, for the purposes of assessing lung function. |
IP Reference | GB1500257.9 |
Protection | Patent application published |
Year Protection Granted | 2015 |
Licensed | No |
Impact | We are in the process of developing a formal relationship with King's College Hospital, who have been testing the system for some time. The respiratory physicians have discovered some extremely interesting characteristics of human breathing being revealed for the first time by this system. We are now seeking funding for further research. |
Title | Respirometer Mk. II |
Description | This is a high-speed, ultra-high sensitivity spirometer intended for use in respiratory diagnostics. The device provides information never before available to clinicians, so the diagnostic value is still being explored. Preliminary, pre-clinical trials have been carried out, and the data is still being assessed in collaboration with colleagues at King's College Hospital in London. Funding is currently being sought for further development and trials. |
Type | Diagnostic Tool - Non-Imaging |
Current Stage Of Development | Refinement. Non-clinical |
Year Development Stage Completed | 2015 |
Development Status | Actively seeking support |
Impact | The interest generated by this product and the capability enabling its developmed has led to the formation of a new university start-up company, Surrey Sensors Ltd. |
Company Name | Surrey Sensors Ltd. |
Description | This is a new university start-up formed as a partnership between industry and academia. The company's aim is to manage the research group's commercial activities and to commercialize the technology being developed by the group. |
Year Established | 2015 |
Impact | The company is still in the process of being set up. |
Description | Active route is hard way to fight drag |
Form Of Engagement Activity | A magazine, newsletter or online publication |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Media (as a channel to the public) |
Results and Impact | A general-interest article appearing in a popular trade magazine, describing some aspects of this work. After an invited seminar delivered on the subject of the work undertaken as part of this research grant, the PI was interviewed by Flight International, and the work was summarized in the mainstream media (Flight International, 15-21 May 2012, p.25) My work received some attention from the materials community |
Year(s) Of Engagement Activity | 2012 |
Description | Nanocomposites Take Flight: Working Smart |
Form Of Engagement Activity | A magazine, newsletter or online publication |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Public/other audiences |
Results and Impact | The seminar delivered by the PI by invitation at the HiPerNano on the subject of this work was reviewed by Materials World, a trade magazine with a readership within the materials community. This was an article reviewing the work done under this grant. The article appeared in a popular trade magazine, Materials World (June 2012, p.9), and highlighted the opportunities for interdisciplinary collaboration in the field of aerodynamic flow control. The work received broad attention, and even caught the attention of those working in fields as diverse as food security. |
Year(s) Of Engagement Activity | 2012 |