Engineers at NASA are studying how game balls in sports are able to move through the air to help them develop new spacecraft designs for future space missions.
Rabi Mehta, head of the space agency's Experimental Aero-Physics Branch at the Ames Research Center, explained that they decided to focus on the aerodynamics involved in sports to provide future generations of NASA researchers something very relatable.
Researchers study aerodynamics to determine how certain fluids are able to pass through objects with specific shapes such as spheres and cylinders. This allows them to find out how they can alter the flow patterns of fluids by making even slight changes on an object's design.
In sports, aerodynamics serves an important role in determining how game balls are able to fly when thrown in the air. Sports scientists make use of fairly simple visualizations of fluids flowing over balls to figure out the best way to throw them and why they tend to curve while in flight.
For their research, NASA scientists used water channels and small wind tunnels together with high-speed wind tunnels at the Ames Research Center to create controlled environments where sports balls can be exposed to fluids at various speeds.
They also use other elements, such as lasers, smoke and even brightly colored dyes infused with the fluid flow, in order to identify smoothness or disturbance patterns that could appear during aerodynamics tests.
"What we are looking for in the smoke patterns is at what speed the smoke patterns suddenly change," Mehta pointed out.
"There is a thin layer of air that forms near the ball's surface called the 'boundary layer,' and it is the state and behavior of that layer that is critical to the performance of the ball."
Mehta added that the ball's material, surface roughness and distribution are all important factors to consider when finding out its aerodynamics.
One example of how a ball's design affects its aerodynamics can be seen through the movement of a golf ball in the air.
Dimpled golf balls can travel at a far greater distance than a smooth one. This is because the dimples on the balls' surface allow the boundary layer to become "turbulent", which in turn keeps the layer attached to the ball longer and delays the separation.
Allowing the boundary layer to separate from the ball would result in a pressure imbalance and drag, causing the ball to slow down in its flight.
Another example is when a quarterback throws a football during a game. Mehta said that a player would want to throw the ball in a tight spiral with a high enough rotation rate in order to keep it stable as it moves through the air.
Doing so would allow the ball to fly at a faster pace because it meets little resistance from drag. It will also allow the receiver to catch the ball more easily compared to wobbling balls.
Photo: Kevin Dooley | Flickr
