in the real world wind tunnel correlation actually means wind tunnel correlationpeewon wrote: ↑21 Jan 2025, 04:31These two articles are a good insight into how wind tunnels are setup and what requirements are placed on wind tunnel testing under current aero regulations.
https://www.motorsport.com/f1/news/the- ... /10672095/
https://www.motorsport.com/f1/news/how- ... /10671540/
They are using special wind tunnel tyres provided by Pirelli.Greg Locock wrote: ↑21 Jan 2025, 22:15They don't use real tires in the wind tunnel, they are just black round things. Well I suppose that is obvious since nobody could make a 60% scale model of a tire that performed at 60%.
Newey recalls in his book 'how to build a car' that they once had an aerodynamic instability issue due to tire flexing in high speed corners which was overlooked in the wind tunnel with the dummy tires. When they changed the dimension of the dummy tire to simulate the behavior during high speed cornering they were managed to overcome the issue. That was 15 years ago, shouldnt they have improved on such states, or can they check thst woth CFD?Greg Locock wrote: ↑21 Jan 2025, 22:15They don't use real tires in the wind tunnel, they are just black round things. Well I suppose that is obvious since nobody could make a 60% scale model of a tire that performed at 60%.
I would say not ...
Motorsport
Racing has its own demands of a wind tunnel, and those differ enough from the requirements of production car testing that it is difficult for one tunnel to be good for both purposes. Along with the variable nozzle, HALO overcomes this with other technology. “We have designed the tunnel to make the switch from road cars to race cars fast and efficient,” Unger explained.
It is the racing focus on downforce that makes the wide-belt system necessary. “For most road cars the focus is on drag, whereas for an Indy car or an Acura DPI machine the focus is not only reducing drag but also maximizing downforce,” he said.
“For racing, the ratio of drag to lift is known as aerodynamic efficiency, one of the primary focuses of development here at the wind tunnel. The majority of the downforce in a race machine comes from the undertray, which, with our unique wide-belt system, is specifically suited exactly for this capability.”
Other Key Features
HALO has other technical details that contribute to both the tunnel’s capabilities and to its efficient operation. Consider the need for engineers to know the frontal area of vehicles being tested in the tunnel. HALO has a system of cameras and lasers to provide that information quickly. “We can measure the frontal area as well as the side area of the car,” reported Unger. “This all feeds into the calculation, which allows us to get the very precise information we need when we are testing in the tunnel.
Not all aerodynamic testing is done with the vehicle pointed straight into the wind, so HALO is equipped with a 180-degree turntable. “This allows us to test at various, and sometimes extreme, yaw angles,” he said. “As well, it allows us to load and unload the car as quickly and as efficiently as possible.” Honda’s engineers are always looking at keeping the operation efficient!
HALO has a giant robot arm that reaches down from the ceiling to take measurements from anywhere inside the tunnel’s test section. The 80-ton arm carries a probe on its tip to measure pressure, velocity, sound or other conditions. “The purpose of this tool is to allow the test engineer to look into detailed phenomena to understand exactly what is going on with the flow field,” stated Unger.
Anyone who remembers Boyle’s Law and its description of the relationship between temperature, pressure, and volume of a gas will recognize the necessity of HALO’s heat exchanger, which preserves a consistent temperature in the tunnel for testing. It is also important to test vehicles are different temperatures, to understand the effect that has on their performance.
“We have the capability of changing the temperature between 10 degrees C and 50 degrees C,” he said. “The reason we do this is that cars are made of various materials, steel, aluminum, carbon fiber, plastic, rubber, and so forth. These all expand and contract at different rates. All of these things impact aeroacoustics and aerodynamics. With this capability we have the ability to understand that much more closely than in the past.”
