How engines work

[HAL9000]

These animations have been on the internet for a long time, but I thought I would create a post for those who haven't seen them

Suck, squeeze, bang, blow.

The engine sucks in a mixture of fuel and air, then squeezes it together (compresses it), then it burns / explodes that with a bang, and finally it blows out the exhaust.

How a Car Engine Works - Animagraffs

Inside a Jet Engine - Animagraffs

 

[SheilaNaGig]

Oh my god thank you!

The workings of the internal combustion engine are a total mystery to me. I have a better grasp of the offside rule than of what goes on when I'm moving around in engine driven vehicles.





(I have no idea what the offside rule is all about.)

 

[existentialist]

Oh my god thank you!

The workings of the internal combustion engine are a total mystery to me. I have a better grasp of the offside rule than of what goes on when I'm moving around in engine driven vehicles.





(I have no idea what the offside rule is all about.)

I DO know (generally) how engines work, but still have not the slightest idea about the offside rule, despite having had it explained at tedious depth a number of times. I think it's because I don't actually care

 

[SheilaNaGig]

So it's the opposite of breathing....?

The diaphragm descends, pulling the base of the lungs along with it, which draws air into the lungs as a result of negative pressure.


The internal combustion engine pushes the diaphragm down by means of a little explosion just above it.

 

[SheilaNaGig]

I DO know (generally) how engines work, but still have not the slightest idea about the offside rule, despite having had it explained at tedious depth a number of times. I think it's because I don't actually care

Yeah, I don't care either. It's a good way to make someone talk for a while if I need to drift off for some reason.

 

[hash tag]

The offside rule is one thing but what about the duckworth Lewis method?

I'm fine with infernal combustion engines but, shamefully, cannot get super boilers in a steam loco

 

[Mrs Miggins]

I'm fine with the car one - that's pretty straightforward but the jet engine - nope - I don't understand what it's doing

 

[HAL9000]

jets engine also use the same cycle...

suck, squeeze, bang, blow

But jets use rotating blades, to suck and squeeze the incomming air. Then tubines near the exhaust collect the energy from the blow part to power suck and squeeze stages. Summary looks like this..

Jet Engines

 

[hash tag]

suck, squeeze, bang, blow

/QUOTE]

Now you are talking

 

[Mrs Miggins]

I think what I don't yet understand is this:
- car engine converts the up and down motion of the pistons caused by the explosions into circular motion which drives the wheels. All good. All mechanical. I get it.

- what is a jet engine doing? Taking in air, compressing it massively, mixing it with fuel, exploding it causing rapid expansion of gasses which are then blown out of the back and all that hot expanded gas creates the forward motion?

Is that it? (Please be kind to me )

 

[HAL9000]

I think what I don't yet understand is this:
- car engine converts the up and down motion of the pistons caused by the explosions into circular motion which drives the wheels. All good. All mechanical. I get it.

- what is a jet engine doing? Taking in air, compressing it massively, mixing it with fuel, exploding it causing rapid expansion of gasses which are then blown out of the back and all that hot expanded gas creates the forward motion?

Is that it? (Please be kind to me )

Yes

 

[Crispy]

I think what I don't yet understand is this:
- car engine converts the up and down motion of the pistons caused by the explosions into circular motion which drives the wheels. All good. All mechanical. I get it.

- what is a jet engine doing? Taking in air, compressing it massively, mixing it with fuel, exploding it causing rapid expansion of gasses which are then blown out of the back and all that hot expanded gas creates the forward motion?

Is that it? (Please be kind to me )

Exactly that. They take a little bit of energy from that hot expanded gas to drive the compression stage.

Modern civilian jet engines actually take most of that energy and use it to drive a big fan, which pushes air *around* the hot bits of the engine. Much more efficient. That's why modern engines are so much larger and quieter than old ones. Military engines want raw power, so all the air goes through the hot bits. Smaller, but louder.

And then *rocket* engines are the same again, just without the "taking in air and compressing it" bit.

 

[Mrs Miggins]

Yes

Wooo! Thanks for that. You know I really didn't know how they worked and now I do. On the simplest of levels but that's kind of all I need.

 

[Mrs Miggins]

So how does a turbo charger work? What does that do?

 

[Mrs Miggins]

Oh and I'm also very pleased to learn what V8 means

 

[hash tag]

And for our next lesson what about a flat four, a V8, a boxter layout or, when you are ready for it (my desire), a hemi?

 

[Mrs Miggins]

Exactly that. They take a little bit of energy from that hot expanded gas to drive the compression stage.

Modern civilian jet engines actually take most of that energy and use it to drive a big fan, which pushes air *around* the hot bits of the engine. Much more efficient. That's why modern engines are so much larger and quieter than old ones. Military engines want raw power, so all the air goes through the hot bits. Smaller, but louder.

And then *rocket* engines are the same again, just without the "taking in air and compressing it" bit.

So rocket engines are literally just burning fuel and forcing all the exhaust gasses out in 1 concentrated direction?

 

[Mrs Miggins]

And for our next lesson what about a flat four, a V8, a boxter layout or, when you are ready for it (my desire), a hemi?

Steady on mate! How about you tell me how a 2 stroke engine works first. Which are the stages missing from the 4 stroke?

 

[existentialist]

So how does a turbo charger work? What does that do?

A turbo charger compresses the air being fed into the engine. It does so by using the flow of exhaust gases to spin a pump very, very fast, which pressurises the air going into the carburettor/injectors.

In the olden days, they'd have used "superchargers", which were lower-speed pumps driven off the engine direct, before the materials able to manage the high temperatures and speeds of the turbocharger part were available.

 

[Mrs Miggins]

This is all 100% more interesting than the offside rule.

 

[hash tag]

PS, similar in layout to the V8 is the V6. Alfa's used to make a beautifully balanced one.
Similar mechanics as any other engine, different layout

 

[HAL9000]

I think what I don't yet understand is this:
- car engine converts the up and down motion of the pistons caused by the explosions into circular motion which drives the wheels. All good. All mechanical. I get it.

- what is a jet engine doing? Taking in air, compressing it massively, mixing it with fuel, exploding it causing rapid expansion of gasses which are then blown out of the back and all that hot expanded gas creates the forward motion?

Is that it? (Please be kind to me )

But....

the jet engines on passenger aircraft are not called jet engines, they're called...


Turbofans

Central part is the jet engine. The big fan at the front pushes lots of air that bypasses the jet engine, the reason for this is to reduce noise and reduce the amount of fuel needed to produce the same thrust

 

[Crispy]

So rocket engines are literally just burning fuel and forcing all the exhaust gasses out in 1 concentrated direction?

Yep!

 

[Mrs Miggins]

A turbo charger compresses the air being fed into the engine. It does so by using the flow of exhaust gases to spin a pump very, very fast, which pressurises the air going into the carburettor/injectors.

In the olden days, they'd have used "superchargers", which were lower-speed pumps driven off the engine direct, before the materials able to manage the high temperatures and speeds of the turbocharger part were available.

And this increases the power how/why? Because the more compressed the air is, the greater the explosion/expansion? So you can use less fuel but create more power?

Also...I don't know what a carburettor does.

 

[pseudonarcissus]

I present the Doxford Marie engine

 

[pseudonarcissus]

For balance

 

[Mrs Miggins]

View attachment 185483
I present the Doxford Marie engine

Looking at this gives me great pleasure. It's very elegant.

 

[existentialist]

And this increases the power how/why? Because the more compressed the air is, the greater the explosion/expansion? So you can use less fuel but create more power?

Also...I don't know what a carburettor does.

Let's start with the carburettor.

For an engine to work, it needs fuel, air, and a source of ignition. It's important that the fuel and air are as well mixed as possible when they are ignited, so that you get the most efficient burn. In older petrol engines, this was achieved by feeding a precise amount of petrol into a chamber via an atomiser, to be mixed with a current of air. That was then sucked into the cylinder, and "bang". Nowadays, we use an "injector" which does just that - injects a carefully-calibrated quantity of fuel into the cylinder direct, as air is also drawn in.

A normally-aspirated (non-turbocharged) engine sucks the air in through a manifold, and a filter. This means that the pressure, and therefore the amount, of air that ends up in the cylinder is less than if it had all been at ambient pressure. The notion is that even higher input pressures will get even more air into the cylinder, allowing you to burn a correspondingly greater amount of fuel at the most efficient ratio to the air ("volumetric efficiency"), and gain greater power. So you use a turbocharger (exhaust-driven) to actively "blow" the air into the engine under pressure. The advantage of using exhaust is that it's (mostly) just energy going to waste otherwise - superchargers "stole" a proportion of the engine power in order to provide the (significant) boost in power they offered.

 

[mauvais]

And this increases the power how/why? Because the more compressed the air is, the greater the explosion/expansion? So you can use less fuel but create more power?

Also...I don't know what a carburettor does.

No - because for a given volume of air, you can mix a given amount of fuel into it, in order to get the ideal combustion ratio. Turbochargers allow you to add more air, and so more fuel, so power is increased.

Carburettors... In the picture in the OP, fuel is injected directly ('direct injection') into the cylinder, which is relatively modern. Before that, it was mixed in the intake port, and the air entering the engine was a fuel/air mix. How do you make the mix? Well, before direct injection, it was still done with electronically controlled injectors - same thing, just not direct. But before that, it was mixed with a mechanical device, and that was a carburettor.

 

[Baronage-Phase]

I DO know (generally) how engines work, but still have not the slightest idea about the offside rule, despite having had it explained at tedious depth a number of times. I think it's because I don't actually care

I know the offside rule...
Not as sure about engines but if pushed I could possibly explain.