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Tuesday, October 28, 2008

The science of speed

Bloodhound SSC project logo
Bloodhound SSC project logo


How world class UK research is behind the fastest car in the world

World class UK research is helping to build the fastest car in the world thanks to the Engineering and Physical Sciences Research Council (EPSRC).

The BLOODHOUND SSC Project, led by Richard Noble OBE, is aiming to set a new world land speed record of a thousand miles per hour by 2011.

The challenge at the heart of the project is to create a car capable of 1,000mph - a car 30% faster than any car that has gone before.

An aerodynamics team at Swansea University – funded by EPSRC – is playing a vital role. Using Computational Fluid Dynamics (CFD), the team has spent the last year creating the predictive airflow data that has shaped the car.

In time, the research could lead to better vehicle or aircraft design, improved fuel efficiencies, and even new medical techniques.

“From the nose to the tail, anything that has any kind of aerodynamic influence we are modelling,” says researcher Dr. Ben Evans – who as a school boy watched the Thrust SSC record on TV.

“It’s the kind of thing aerospace engineers would have traditionally done in a wind tunnel, but we’re doing it on a computer, a big multi-processor super computer. Wind tunnels have massive limitations. BLOODHOUND SSC is a car, so it’s rolling on the ground and there are no wind tunnels in existence where you can simulate a rolling ground with a car travelling faster than mach one, faster than the speed of sound.”

Richard Noble with image of the car behind him

Richard Noble, current holder of the world land speed record with the Thrust SSC team.

This ‘mach factor’ is the major difference between this vehicle and its predecessor Thrust SSC. Thrust SSC was a supersonic car in that it crossed the sound barrier and was supersonic for a matter of seconds.

But with BLOODHOUND, the target speed is 1,000mph - mach 1.4. It will be going supersonic way beyond mach one, and for a much longer time period, which means the supersonic shockwaves it creates will be far stronger than Thrust SSC, and they will interact with the car and the desert floor for much longer.

“Once you start approaching, and go beyond the speed of sound, you can no longer send a pressure wave forward to tell the air ahead of you you’re coming,” explains Evans. “What happens is a big pressure wall builds up in front of you. Rather than air slowly and smoothly getting out of the way, at supersonic speeds these changes happen very suddenly in a shockwave.”

Supersonic aircraft create these shockwaves and they dissipate in the surrounding atmosphere but still reach the ground as a ‘sonic boom’.

Evans adds: “What we’re trying to understand is what happens when this shockwave interacts with a solid surface which is a matter of centimetres away.”

What the team do know is this ‘interaction’ creates a phenomenon known as ‘spray drag’ – a term first coined by BLOODHOUND team member and aerodynamicist Ron Ayers during the Thrust SSC attempts.

Spray drag is an additional drag component not accounted for in aerodynamic or rolling resistance theory.

“As the car interacts with the desert, and the shockwaves interact with the desert, they actually eat up the desert floor,” says Evans.

“That introduces sand particles into the aerodynamic flow around the car and this interaction is not accounted for in standard CFD work. We plan to look at this spray drag phenomena, what happens and when, and how the sand particles impinge on the car.”

The Swansea team are also looking at key systems in isolation. Work has already changed the car from twin to single air intake for stability.

Bloodhound team members grouped around a computer monitor
Bloodhound team members - from left to right: Brian Coombes, Ben Evans and Mark Chapman

The car will also sport solid titanium wheels with twin ‘keels’: “That was fundamentally an aerodynamic design decision,” says Evans. “We studied different design options, a single keel running down the centre of the wheel, a design that had three keels and finally the one we went for with two keels. It was chosen as a compromise between lift and drag patterns and minimising the pressure disturbance around the wheel on the desert surface.

“Another thing we have been looking at closely is the exact nose shape. We want a nose that constantly generates a small down force on the front to help keep the car on the ground. But we’re also constantly looking a how we can minimise spray drag and if we can constantly achieve a positive pressure on the desert surface leading up to the front wheels then hopefully the surface will remain intact until the front wheels roll over it.”

But Evans and the team also remain focussed on the wider aims of the project and the application of their research in other areas.

“The whole point of doing this is not just to create a fast car. We live in a carbon economy and lots of the issues we face will require engineers and scientists to solve them – part of this project is to inspire young people.”

And sat at his desk in Swansea he has a constant reminder of the potential of CFD.

“Some of my university colleagues are working on blood flow monitoring through the arterial system and trying to predict when aneurysms will explode through pressure loadings.

“On one side of the office we have pictures of Bloodhound and on the other we have pictures of blood flow through the heart.

“There are the obvious applications in aerospace, but any application you can think of that involves fluid flow can be modelled using CFD. Biomechanical systems seems to be one of the areas CFD is being applied to now.”

For more information or interviews contact:

EPSRC Press Office on (01793) 444404 or e-mail: lawrie.jones@epsrc.ac.uk

More information is available on the Bloodhound SSC project website and the EPSRC Bloodhound SSC webpages.

Notes for Editors:

EPSRC Podcast Available

An 18 minute podcast featuring the science and engineering behind the project is available on the EPSRC website (www.epsrc.ac.uk). This includes detailed interviews with Richard Noble and Ben Evans and recording from the cockpit of THRUST SSC when the current World Land Speed Record was set in 1997 ( the use of the cockpit recording was provided courtesy of Jeremy Davey: www.thrustssc.com/).

BLOODHOUND SSC

EPSRC has provided funding of £740,718.55 for the computational modelling of the aerodynamics research for BLOODHOUND SSC, which is being carried out at the Civil and Computational Engineering Centre, School of Engineering at Swansea University.

Bloodhound brings together the UK’s leading STEM organisations and technology-based companies (STEM – Stimulating the interests of young people in Science, Technology, Engineering and Mathematics) for more information visit http://www.stemcentres.org.uk/)

Apart from EPSRC and Swansea University other major participants include: the Ministry of Defence, Serco Group plc, the University of the West of England, Clorox, the Engineering and Technology Board, the Royal Academy of Engineering, the Royal Air Force and the Institution of Engineering and Technology.

About EPSRC

The Engineering and Physical Sciences Research Council (EPSRC) is the UK’s main agency for funding research in engineering and the physical sciences. The EPSRC invests around £800 million a year in research and postgraduate training, to help the nation handle the next generation of technological change. The areas covered range from information technology to structural engineering, and mathematics to materials science. This research forms the basis for future economic development in the UK and improvements for everyone’s health, lifestyle and culture. EPSRC also actively promotes public awareness of science and engineering. EPSRC works alongside other Research Councils with responsibility for other areas of research. The Research Councils work collectively on issues of common concern via Research Councils UK.

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