Tuesday, September 1, 2009

Soap Bubbles to Decrease Drag of Future Cars

Bubbles Decreasing Drag in Future CarsWe've heard a lot of different ideas about different fuel types to use instead of gas and other things we could use to make cars work better and pollute less. But could something as small as the bubbles from your soap actually be enough to decrease the drag in your car? The Engineers at Mira, an automotive research company in Nuneaton, UK seem to think so.

According to the studies by Mira, helium filled soap bubbles are helping to improve fuel efficiency. The 3-millimeter bubbles swirl around cars in a wind tunnel. The bubbles have a natural buoyancy due to the helium in them. If left to themselves, the bubbles will simply float in place, neither rising nor falling. Therefore, any movement in their position can be directly attributed to the air flow around the car.

According to aerodynamics specialist and lead developer of the soap bubble system Angus Lock, "There aren't any tools in use today that can give such insight into what's going on in the fluid around a vehicle."

Two of the biggest factors consumers are considering when buying a new car these days are fuel economy and carbon emissions. This being the case, aerodynamics have become a more important factor to car manufacturers. Instead of reworking a car's drive train or the entire engine, cutting a vehicle's air resistance is usually cheaper.

Although it sounds great, the bubble technique isn't exactly a new idea. People have used the bubble technique to see how air flows around different structures. However, Mira uses a 12 camera system to get intricate details about the bubbles and how they move. The system captures the movements of the bubbles which can be transformed into 3D images for later analysis.

The gold standard for looking at a cars aerodynamics is still full-scale wind tunnel tests. "It is simple to try out new ideas for improving streamlining by simply swapping parts of the car in the tunnel." , Lock says. Sensors in the tunnel measure how the car interacts with the air rushing past it.

One problem, according to Lock, is that they can not visualize the whole field around the vehicle which means you don't know what is behind those forces. Using the bubble tracking method, the speed and direction of the air flow can be captured. This makes it more useful than existing tracking techniques such as injecting smoke trails around the car.

The infrared camera system from Vicon that Mira uses is the same kind typically found in a motion capture studio for video games and movies. Mira pushes the cameras to their limits in order to track the light reflected from the bubbles. "We are are thinking about what we can do to the bubbles to make them easier for the cameras to see," says Lock.

One idea the team is considering is building a machine able to produce larger bubbles. These larger bubbles would have to be filled with a mixture of helium and air in order for them to achieve natural buoyancy. Another machine Lock's team is working on is one that produces more bubbles as well.

Even though computer simulations are as sophisticated as ever, finding different ways to show complex air flows visually is a critical part in understanding aerodynamics. Finding ways to accomplish this in large wind tunnels is also very valuable. According to Alex Liberzon of Tel Aviv University in Israel, "You can not solve everything completely in space and time on a computer. Simulations do not capture the full complexity of wakes and other features, which can exhibit large changes in behaviour caused by very small changes."

Fuel efficiency is one of the biggest concerns for people all over the world. In recent years people have been working extremely hard on finding better ways to power not only our cars but also everything else we use. With techniques like the bubble technique, we are just that much closer to finding a solution.

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