How Rocket Engines Work - Part 6 - Injectors

[@melonmusk6008]

my man finally came back from getting milk after 3 years

[@stevefink6000]

your degree, oh my god, look at that subtle off white color, it even has a water mark🤣 Nice Job on the paper, and thanks for the great video!

[@leavoa]

Congratulations on the degree! Onwards, upwards, and very fast sideways!

[@PrimeSuperboy]

Congrats on earning the comparatively free time! Your videos are extremely informative so I hope you keep up the content.

[@thunderace2517]

Man we missed you. Welcome back!!

[@bramv1984]

Awesome video! And I loved the 'business card' reference ;)

[@epaxinc1019]

Nice video! Happy to see the serie continue

[@nikolatasev4948]

Great video, and congrats on the degree. Can you make one about the advancements and differences between old (Apollo era) and modern engines? I don't think there is such great improvement in efficiency (NK-33 from the 60s was still a decent engine when it flew in 2014), but perhaps in control, reliability and labor-intensity? I suppose it is much harder to drill thousands of holes with millimeter precision is harder than to put a single pintle/swirl injector, but would love to learn about less obvious differences. I would also love a video about the tradeoffs in designing a rocket engine, why some approaches got more or less popular with time.

[@jmstudios457]

It's not really in performance I think but the main differences are in development and manufacturing. new metallurgy allows for higher combustion temperatures and chamber pressures, new machining techniques allows for faster or simpler construction, additive manufacturing means more complex parts can be manufactured relatively easily, better computer modeling techniques means allows for cheaper, more analytical approaches to pump, turbine and injector design

[@jmstudios457]

Different impinging patterns are generally used for different propellents, double impinging and self impinging work best for hydrocarbon and hypergolic propellents, triplet impinging works best for hydrogen/oxygen

[@ROSHAN_GOAT]

Hey why are you not making more video this video is great man

[@jmstudios457]

"With deeper throttling, oxidizer and fuel flows tend to oscillate and will usually bo longer remain at their original mixture ratio, the propellent injection streams become erratic. Yo prevent this, engines need to have some special features like those found in the engine used on the first lunar landing rocket...each propellent flow control valve included a cavitating venturi with a moving tapered pintle... This assured predetermined stead reduced flows of propellents at all thrust levels, and maintained a constant mixture ratio... It allows for high injection velocities of liquid propellents, giving good atomization and adequate combustion with relatively small losses on performance at low thrusts." Chapter 8.8, Rocket Propulsion Elements :)

[@Exploreweb-k9f]

I wanna know how the injector, fuel pipelines and ignition are arranged in the engine

[@aldunlop4622]

Man I struggle just to get my garden hose flow rate right! It seems to be different every time I turn it on. Can’t imagine how hard is to get rocket engines to work. I know SpaceX actually have a simulation program that I assume they run on something like a supercomputer that calculates flows. I saw a video of this about 4 years ago from McGregor.

[@WilliamDye-willdye]

Congrats, grad. I hope it pays off for you.

[@Chris-os3zl]

The normal spray injectors won't be that efficient Right?

[@Chris-os3zl]

Hmmm..... the pressure plays a crucial role

[@IstasPumaNevada]

Congrats on the degree. :)

[@nickmerix2900]

How does the propellant stay in the chamber in space? On earth its atmospheric pressure but in space ? Wont the propellant dissipate into the space vacuum before it gets a chance to ignite?

[@SpaceIsKindOfCool]

The whole goal of the rocket engine is to throw the propellant into space as fast as possible, but the time it takes to ignite is a consideration. If the combustion chamber is too short the propellant will indeed exit before it ignites. Luckily these reactions take place in very short amounts of time, so the combustion chamber doesn't need to be too long. The amount of time the propellant is in the chamber is only a fraction of a second, but for modern engines that's enough to burn.

[@nickmerix2900]

@@SpaceIsKindOfCool but once ignited it requires pressure to create thrust . The space vacuum would prevent any pressure build up. It would be like an inflated balloon , when released the exiting air would provide thrust . But if we attach a vacuum hose to the mouth of the balloon then any air released would be sucked out immediately preventing any thrust

[@SpaceIsKindOfCool]

@@nickmerix2900 In your example any air sucked out of the balloon, even if it were due to a vacuum, would indeed cause thrust. It's Newton's laws of motion, any action has an equal and opposite reaction. As for vacuum causing there to be no pressure build up in the engine, this is also false. Since the nozzle is a constriction any flow through it will result in a pressure build up.

[@nickmerix2900]

@@SpaceIsKindOfCool newtons third law does not apply to all forces. Example buoyancy, gravity, and pressure gradient. If we apply newtons third law to lets say a hot air balloon then it should never Lift of the ground. Or when a pressure gradient causes winds to blow south with force x we dont see an x force to the north also. If i drop a 5 kg weight from height it will fall with a force of say 50 newtons but i will not feel that force on my hand. In these situations we have force with no opposite force . Rocket exhaust is basically pressurized gas moving to lower pressure ie pressure gradient. And gas expanding in a vacuum is free gas expansion

[@SpaceIsKindOfCool]

@@nickmerix2900 Newton's laws absolutely do apply to all forces. In all of your examples the object which feels the equal reaction is the Earth (or the Earth's atmosphere). When you drop that 5kg weight it falls, but the Earth also rises to meet it, you just don't notice it because the Earth is so massive that 50 N doesn't move it very fast. In the wind example if you were to take the total momentum of the Earth and its atmosphere you would find it never changes. If the wind blows stronger in one direction the entire Earth must have a change in rotational velocity in the opposite direction.

[@何明果-w7e]

Very good videos, very proud of you! I got my PhD from University of Minnesota back in 1991,