How Jet Engines Work

[disguised]

Thank you! Finally an animation that shows the propellers rotating the right way.

[bruzote]

This video is more awesome than people may realize. This video captures the following visual information I have not seen in other videos. First, it shows clearly how the air flow volume is actually only a thin cylinder around the spinning fans. Most pepole don't realize that air hitting the engine does not go through the engine even close to the center. Second, it shows how this particular kind of engine has not one but two coaxial counter-rotating shafts. Three, it clearly shows the angle of the compressor blades (I mean the moving blades) and the stator blades (the fixed position blades along the outside). Fourth, the second and third features combined allow you to imagine how the air flows from the forward exterior fan, gets pushed through and will start spiralling, and the *spiral* flow from the front engine fan then meets the first row (part of first stage?) of compressor blades at a *low* angle of attack (the blades are efficiently moving through spiraling air like a wing). I always wondered how the blades were not acting like a wall pushing air. It's because the air coming at them is spiraling and not racing straight in. This reduces the angle of attack, so the compressor blades don't create turbulence (or stall). Then you can imagine (yes, you need to imagine) how the first row of blades starts reducing the spiral flow, so the next row of blades needs to be angled to face more of an axial than spiral flow. This continues through the compressor stage. The video does fail to mention there are two stages (or three? if you count the front blade?). From what I call the first stage, the air still has some spiral motion, and the second stage of blades then rotates in the opposite direction from the first, allowing the blades (like before) to meet the air with less angle of attack. This allows for reduced turbulence/stalling while allowing the blades to do more work. Again, the fans have less and less angle as you go from front to back. All while this is happening, look how very little space the air is moving through. It gets smaller! Now, an engine working at a steady speed always has a steady amount of air mass moving through it (lets say pounds per minute). Each slice of the engine has the same flow rate. Where I pointed out the cylinder gets smaller, the mass moving through has less space, so it must be more dense. That means it *must* be at higher pressure (unless you could magically cool it to reduce the pressure). So, you see the air must be flowing through at higher and higher pressure. Then, when it gets past the second stage (second set of fans), the flow is allowed to expand where it meets the fuel. NORMALLY, expanding air flow reduces the pressure. However, the fuel is ignited at the expansion point. The heat is just like an explosion - it prevents the pressure from dropping. So, you go from a narrow, high-pressure flow to an expanded area with similar pressure. Note - the pressure is NOT greater in the combustion chamber than right upflow. If it were, the flames would move forward. No, the pressure actually DROPS in the expanded flow in the combustion chamber but not much. However, although pressure keeps dropping from final compressor fans to combustion, the ENERGY/work put into the air dramatically increases due to the burning fuel that is preventing the pressure drop in the expanding flow volume. Then, this air is once again squeezed through a narrowing opening, speeding it up and meeting the exit stage of the turbine. (I don't know the terminology.) I may sound rambling, but my point is - I have not seen a video that allows you to see the moving parts this way. I am especially stunned I did not know (a) how narrow the air flow cylinder is and (b) that the engine has counter-rotating shafts, one poking through the other. Cool!

[tamar]

Please loose the irritating music. Good video.

[jasonlake]

Thank you pratt & whitney..only video that has made sense..now I understand jet engines

[KhoPhi]

One of the most educative adverts I've seen in a while

[kelseyj]

That made so much sense. So glad I could learn this!

[jaimemartin]

Very cool. I didn't know the blades turn in opposing directions... I've seen these engines in museums cut open to see inside, but I couldn't figure out how the things don't just shoot flame out of both ends!

[joshispro]

This was a really well animated video and it was very easy to understand thank you!

[karlwolf]

The trick to higher fuel efficiency? An amazing gear.

[bruzote]

This is all amazing, but I still also love even more watching a simple afterburner take-off and feeling it rattle my bones! :-D Well, I guess I can't do that anymore. I only served a brief time and I am not near SR-71s or other AB-equipped jets that are taking off. (OK, nobody is near SRs taking off anymore, but one time I had a single privilege of witnessing that.)

[trueindian]

Beautiful explanation.I understood the jet engine concept clearly.Ty and keep it up.

[gustavoechevarria]

So lemme get this straight, a Jet engine is basically a recoilless rifle and a turbo conjoined to make continuous combustion a reality.

I thought these engines were much more complicated than regular combustion engines but it seems I was wrong; they seem much simpler than a regular car/truck engine!

[nicholasaquino]

Bring back the LOUD JT8D's. That's how a jet engine should sound"❤

[acemaxximus]

The sound effects helped me understand better, thanks Pratt & Whitney!

[royhsieh]

anything that works on action reaction philosophy will work wonders until physical limitation comes in. this is why i love this

[woozy]

"An AMAZING gear" lmao what, the revolutionary secret to fuel efficiency has been an amazing gear all along

[acreepykiwi]

I like bow P&W put what is basically an equivalent of 'buy my merch' at the end ))

[lowkey]

No one gonna talk about how turbine is pronounce 😆

[vipahman]

My son is joining P&W and will make this tech even better.

[Simon_r]

I already knew how they work but I enjoyed watching it anyway. Good video