Prandtl–Meyer expansion fan
Ok kiddo, so do you know what happens when you blow air really hard into a balloon and then let the air out slowly? The balloon gets bigger, right? But what happens when you let the air out faster? The balloon's sides start to bulge out and it makes a loud noise!
Well, that kind of fast air release is kind of like what happens when a really fast moving gas (like from an airplane) suddenly hits a slower moving gas (like regular air). The fast gas starts to slow down and spread out, kind of like if you put your hand in front of a fan -- the air doesn't go straight anymore, it goes wider.
But here's where things get tricky. When gas spreads out, it starts to change the air pressure around it. This change in pressure creates a weird thing called a "prandtl-meyer expansion fan."
Think of it like this: you have a balloon and you're blowing it up really fast. As you blow, the rubber between your mouth and the balloon expands, right? But if you poke a finger into the rubber or tie a knot in the end of the balloon, it makes a kind of "obstacle" that the expanding rubber has to work around.
The prandtl-meyer expansion fan is kind of like that obstacle, but for fast-moving gas. It slows down and spreads out, but then it comes across something (like air or another gas) that creates a "kink" and changes the way the gas moves. This kink can create a "fan" of slower-moving gas that spreads out at an angle from the original gas stream.
It's called the "prandtl-meyer expansion fan" because two scientists named Prandtl and Meyer figured out how the gas behaves and named it after themselves.
So in summary, when really fast gas hits something slower, it spreads out and changes the air pressure around it, creating a prandtl-meyer expansion fan that looks like a fan-shaped area of slower-moving gas.
Well, that kind of fast air release is kind of like what happens when a really fast moving gas (like from an airplane) suddenly hits a slower moving gas (like regular air). The fast gas starts to slow down and spread out, kind of like if you put your hand in front of a fan -- the air doesn't go straight anymore, it goes wider.
But here's where things get tricky. When gas spreads out, it starts to change the air pressure around it. This change in pressure creates a weird thing called a "prandtl-meyer expansion fan."
Think of it like this: you have a balloon and you're blowing it up really fast. As you blow, the rubber between your mouth and the balloon expands, right? But if you poke a finger into the rubber or tie a knot in the end of the balloon, it makes a kind of "obstacle" that the expanding rubber has to work around.
The prandtl-meyer expansion fan is kind of like that obstacle, but for fast-moving gas. It slows down and spreads out, but then it comes across something (like air or another gas) that creates a "kink" and changes the way the gas moves. This kink can create a "fan" of slower-moving gas that spreads out at an angle from the original gas stream.
It's called the "prandtl-meyer expansion fan" because two scientists named Prandtl and Meyer figured out how the gas behaves and named it after themselves.
So in summary, when really fast gas hits something slower, it spreads out and changes the air pressure around it, creating a prandtl-meyer expansion fan that looks like a fan-shaped area of slower-moving gas.