That fighter pilots often break the sound barrier is something that we are more than clear about. However, exceeding this speed in other vehicles is much more difficult. The formula 1 cars, for example, reach very high speeds, but do not go that far. Although there is a time when a Formula 1 driver can exceed the speed of sound: when you uncork a bottle of champagne to celebrate their victory.
This has recently been demonstrated by a team of French scientists (how could it be otherwise) in a study accepted for publication in Physics of Fluids. In it, they analyze the shock wave pattern that occurs from the moment the cork begins to separate from the champagne bottle until he is thrown away from her.
For this they have used a high speed camera, capable of capturing all the details that the human eye cannot detect. Thus they have seen that the shock waves of the gas reach speeds far above the speed of sound and that patterns similar to those of the launch of a rocket or bullet that is fired from a firearm.
Why do they use a high speed camera?
It may sometimes sound counterintuitive that to see all the details of a video slow motion requires high speed cameras. Where are we, fast or slow?
But the truth is that we do need high speed. To put it simply, you need a high rate of fire. And it is that what these cameras do is capture many frames in a very short time. Thus, you can see all the details and calculate your speed.
In this case, you can see how the cork of the champagne bottle gradually separates. Initially it still prevents the gas flow, then interacts with him and finally walks away. In this process, shock waves are generated that can exceed the speed of sound. But let’s see how.
When champagne goes beyond the speed of sound
The first thing these scientists saw is that as the cork pulls away from the champagne bottle, a coronal shock wave with speeds of almost 1,500 kilometers per hour. This is much more than what a Formula 1 car can achieve and also much more than the speed of sound. So yeah, at that point they’re kind of emulating the fighter pilots. But the thing does not stop there.
Those waves combine to form a phenomenon known as shock diamond. This usually occurs in the combustion columns of the aerospace propulsion systems, when the pressure of the expelled gases is different from the ambient one. Ultimately, a wave pattern characteristic of rockets is formed.
But the process continues. Two-thirds of a millisecond later, the cork in the champagne bottle has already parted some more and a cylindrical flow can form. But it’s not far enough to get out of the way of the gas. At that point something known as bow shock. This type of wave is more common in cosmic phenomena or when a bullet leaves a firearm.
And that is precisely why this study is so interesting. A bottle of champagne is a very easy to get with which it is possible to study various much more complex phenomena in which the speed of sound is exceeded, from rocket launches to the trajectory of bullets.
Even if you are not a Formula 1 driver or an athlete, surely at some point, in the not too distant future, you will open a bottle of champagne. When you do, remember that you could be exceeding the speed of sound. More reasons to avoid gouging out someone’s eye.