Questions tagged [nozzle]
Questions regarding the rocket engine nozzles, semi-open compartments of various shapes and sizes into which propellant components are injected by their own pressure or with a help of a turbine, often preheated and ignited to start a thermochemical reaction in the nozzle's combustion chamber, producing thrust with expansion into gases and ejecting them through the nozzle's exhaust as plumes, accelerating the rocket to high-mach velocities.
87
questions
3
votes
1answer
97 views
Sea-level nozzles
I understand that there are sea level-optimised and vacuum-optimised nozzles, but why optimise for sea level when the rocket doesn't spend much time there? I would expect the first stage nozzles to be ...
4
votes
0answers
87 views
Aerospike calculator software doesn't seem to altitude-compensate - am I misunderstanding aerospikes?
I'm using mvernacc's Aerospike Nozzle Design GUI, which is supposed to be able to design and predict the performance of aerospike rocket engines. The workings of the software are apparently based on ...
4
votes
1answer
131 views
What were the stingiest and most generous vacuum nozzle? (records for the smallest and largest expansion ratios)
Vacuum nozzles are huge compared to their sea-level or atmospheric counterparts, as can be seen by comparing the first stage engines on an Electron or Falcon-9 to their second stages, where a big ...
1
vote
1answer
38 views
nozzle throat area calculation for choked flow
I am quite confused for my sugar propellant rocket nozzle. I have designed a CD nozzle by hit and trial method. It worked but produced so less amount of thrust .I have used 2.3 kg propellant which ...
8
votes
1answer
382 views
How can firing a Space Shuttle OMS engine below 21 km cause its nozzle to “collapse”?
This answer to Can the space shuttle use OMS engines during landing? says:
No
and quotes Section 3.7 of the Orbital Maneuvering System Workbook; OMS 21002 October 10, 2006, Final version, USA006500 ...
16
votes
3answers
1k views
Is it always one nozzle per combustion chamber and one combustion chamber per nozzle?
When I read about engines like the RD-170 they might have a single turbopump feeding multiple combustion chambers, and each combustion chamber has its own nozzle. Is there, or would it be reasonable ...
0
votes
0answers
41 views
Design a cold gas ACS nozzle
I have the total thrust required to be F=16.9 KN. I am using nitrogen gas, and the stored temperature in the nitrogen gas cylinder is 155 bars with a temperature of 325k. How would I design the nozzle ...
5
votes
2answers
417 views
Aerospike with solid fuel
I was scrolling in youtube and I saw this awesome video
and I think, if we put an aerospike nozzle in a sounding rocket,or even a small orbital rocket, as a first stage solid booster, this type of ...
3
votes
1answer
85 views
Do pulse detonation rocket engines require any type of nozzle?
Rocket nozzles are used to convert slow moving gas under high pressure and temperature into hypersonic gas under approximately ambient pressure. From many videos of experimental Pulse Detonation ...
1
vote
0answers
88 views
Which engine has the highest nozzle wall temperature? [closed]
From all the rocket engines that were used in flight, which one has the highest nozzle wall temperature?
The nozzle wall is not heated uniformly. But there are regions where they reach max temperature....
14
votes
2answers
2k views
How hot do rocket engine nozzles get?
What temperatures are encountered by the nozzles of rocket engines like those in SpaceX's Merlin series? Radiative or regenerative cooling, atmosphere or vacuum.
There's plenty of info about exhaust ...
0
votes
1answer
124 views
What if we have a DC nozzle instead of a CD nozzle?
My understanding is that the exhaust gas gains velocity as its heat converts to kinetic energy, regardless of the geometry of the nozzle, and the reason we have a convergent-divergent (CD) nozzle is ...
1
vote
1answer
71 views
I'm having a problem with the Throat Area formula derivation
I came upon this when reading "Introduction to Rocket Science and Engineering, he said "by differentiating" , my question is: differentiate with respect to what? and how do you get such ...
5
votes
1answer
374 views
Contracting rocket engine nozzles
The efficiency of rocket engine nozzles depends greatly on their expansion ratio an how well the ambient pressure matches the rocket nozzles exit pressure. An optimal expansion ratio means that there ...
3
votes
1answer
98 views
At which pressure does a liquid fueled rocket start producing supersonic flow?
In a compressed-tank LOX+ethanol (or similar liquid fuel) rocket:
How much should the tank or combustion chamber pressure (which should be the same) be to have a significant exhaust velocity increase ...
5
votes
1answer
206 views
Can exit pressure of nozzle be less than atmospheric pressure?
This is kinda dumb question .I got 5psi pressure at outlet of the nozzle from open motor software. Is that possible because its less than atmospheric pressure 14.7 psi?
Am i missing out something?
2
votes
0answers
125 views
Why nozzle extensions for ULA's Vulcan; why not make them this long in the first place?
This answer to What is the difference between the Vulcan 562 configuration and the Vulcan 5H2 ("Heavy") configuration? explains that the 2nd stage nozzles were modified by extending them, ...
1
vote
0answers
82 views
Need help finding a clean expression for exit velocity [duplicate]
I'm trying to calculate a engine burning LOX and ethanol (96%) and for that I am using both
CEAgui, a GUI for NASA's CEA (Chemical Equilibrium with Applications) code
Sutton's Rocket Propulsion ...
0
votes
1answer
88 views
Efficiency of rocket stages and converging/diverging nozzle
It is a fact (to the best of my knowledge) that for optimum thrust from a rocket engine, one of the most important factor is the design of its converging/diverging Nozzle - the diverging cone to be ...
4
votes
1answer
169 views
Do converging-diverging engine nozzles need to be bell-shaped?
Many rockets designed after the V2 but prior to Saturn V, do not show the typical "Bell" shaped diverging nozzle. Why is it so? Do they achieve supersonic speeds for the exhaust gases in any other way?...
0
votes
0answers
71 views
Supersonic flow of non-compressible fluids
Will the non-compressible fluids, travelling at Mach 1, at the throat of a CD nozzle, accelerate after they leave the throat?
6
votes
2answers
233 views
Nozzle throat velocity
I have the following question regarding nozzles; It is known that in a CD nozzle there can be only one of the following outcomes;
a flow fully subsonic in the convergent, subsonic at the throat and ...
2
votes
1answer
231 views
Nozzle Exit Pressure Too High?
I've been doing some simple rocket science for fun, and I wanted to calculate the specifications of the Lunar Module Descent Engine (LMDE). The LMDE uses Aerozine-50 (UDMH) and Dinitrogen Tetroxide($...
6
votes
1answer
399 views
What is the thickness of a rocket nozzle?
For a university project, I'm working on optimisation of a Falcon-9-like launch vehicle, and one element of that is varying expansion ratios of the engines. This will impact on the engine mass, but to ...
5
votes
1answer
282 views
What was the first rocket with de Laval (convergent-divergent) nozzle to fly?
Rocket engine Wikipedia article states that
Goddard was the first to use a De Laval nozzle on a solid-propellant (gunpowder) rocket engine, doubling the thrust and increasing the efficiency by a ...
6
votes
1answer
212 views
Why do many ablative nozzles use phenolic resin and not some other resin?
I am currently looking into ablatively cooled nozzles. Most of the nozzles made out of composite material that I have found use phenol as resin (Space Shuttle Solid Rocket Booster, ARCA Excecutor).
...
1
vote
1answer
340 views
What is a typical sea-level engine nozzle/expansion ratio? What about vacuum engines?
On a sea-Level engine, what is the average nozzle ratio? What about an upper-stage vacuum engine?
2
votes
0answers
81 views
Deep throttling in sea level engines
In this excellent answer, asked for merlin engines deep throttling in first stage and produced here.
To help you understand where the cross over point is, here is some math for understanding the ...
2
votes
1answer
141 views
Grossly overexpanded nozzle?
How do we classify a nozzle to be grossly overexpanded in the design phase? For example, looking at the dimensions and operating at sea level, can we determine if it will be overexpanded or grossly ...
11
votes
2answers
3k views
Why should the velocity through the nozzle throat be sonic?
I have read (even on this site), that exhaust gas velocity is (normally?) sonic (exactly Mach 1) through the choke point of a De Laval, or convergent-divergent, nozzle:
At the "throat", where the ...
5
votes
2answers
306 views
What factors determine the altitude at which rocket exhaust plumes start blooming hugely?
The images below are from a much larger set of photos in Spaceflight Now's August 8, 2019 article Photos: Atlas 5 paints the sky with spectacular sunrise launch.
They show several effects related to ...
2
votes
1answer
219 views
Do the pipes used for RS-25 nozzle cooling channel have a constant section?
If I understand correctly from this question, The SSME's nozzle is made of pipes into which cool propellant circulate.
The nozzle is larger at the end than near the combustion chamber. Thus, it must ...
9
votes
1answer
603 views
Sea level static test of an upper stage possible?
As we know that for the upper stages of the rocket, we need high propulsion efficiency thereby high specific impulse. For that we employ a nozzle with higher expansion ratios.
Now, if we conduct the ...
6
votes
2answers
135 views
Does adding a nozzle increase peak pressure in a rocket?
If I had two charges of the same solid propellant both in the same geometry and casing, and added a de laval nozzle to one, while the other would have just a simple hole for an exhaust, upon firing, ...
2
votes
1answer
429 views
Under-expanded nozzle at sea level - is it a problem?
I'm designing a solid rocket motor with a fixed pressure in the combustion chamber $p_{cc} = 70~bar$. When it comes to the choice of the right nozzle, I have to consider the proper expansion ratio, in ...
7
votes
2answers
1k views
Why does the Superdraco exhaust seem so under-expanded in this photo?
The Ars Technica articles
From zero to 100mph in 1.2 seconds, the SuperDraco thruster delivers
Dragon was destroyed just before the firing of its SuperDraco thrusters
both include this "file photo" ...
4
votes
2answers
454 views
What are these big shiny metallic “lumps” on the bottom edge of each Falcon Heavy nozzle?
What are these big shiny metallic "lumps" on the bottom edge of each nozzle of each core of this Falcon Heavy image from the Teslarati article SpaceX reveals Falcon Heavy Block 5 in first official ...
9
votes
1answer
2k views
What is the white spray-pattern residue inside these Falcon Heavy nozzles?
What is the white residue in a spray pattern seen on the inside of each nozzle of each side core of this Falcon Heavy image from the Teslarati article SpaceX reveals Falcon Heavy Block 5 in first ...
5
votes
2answers
309 views
Issue with units for a rocket nozzle throat area problem
I'm working through How to Design, Build, and Test Small Liquid-Fuel Rocket Engines. The guide explains calculating a rocket nozzle throat area using Eq. (7):
$$A_t = \frac{w_t}{P_t} \sqrt{\frac{R ...
0
votes
1answer
491 views
Weight Flow Rate
I read in the book INTRODUCTION TO ROCKET SCIENCE AND ENGINEERING by T.S.T that Rocket Engineers design how big the throat of the nozzle should be based on the Weight Flow Rate.
So my question is HOW?
1
vote
0answers
1k views
Rao contour nozzle: Calculate throat and exit angle?
The Rao nozzle formula is an empiric formula for a parabolic nozzle used in pretty much all nozzles today.
The problem is it depends on the throat and exit-angle of the nozzle, which varies with ...
2
votes
1answer
233 views
How is the exit velocity of the flow in a sounding rocket nozzle?
How is the exit velocity of the flow in a sounding rocket nozzle?
Is it subsonic or supersonic?
Is a de Laval nozzle required for sounding rockets?
Bonus Question: What about Model Rockets?
6
votes
0answers
226 views
Could ablative material sublimation slow down a spacecraft?
Thought experiment illustrated below:
Suppose a weird spacecraft entering Earth's atmosphere from low Earth orbit, payload first. Behind it there is an inverted nozzle shaped structure, attached with ...
0
votes
2answers
479 views
Why are exhaust nozzles in space shaped the way they are? [duplicate]
Why are nozzles in space shaped like a cone and not like a tube ensuring all the exhaust is directed strait?
2
votes
0answers
45 views
What are some common exit pressures for liquid propellant engines?
Most engines are overexpanded at launch so that they reach peak efficiency at altitude. It’s easy to find values for thrust, specific impulse, expansion ratio, chamber pressure, etc, but I’m trying to ...
6
votes
0answers
159 views
What modifications constituted the ‘reorificing’ of F-1 engines on later Saturn V flights?
The topic of uprating the Saturn V’s first stage engines appears to have been widely discussed, and yet there is little agreement as to how it was done.
Early Rocketdyne F-1 engines quote lower ...
2
votes
2answers
286 views
What causes those curtain-like hot and cool spots in the 2nd stage nozzle of this Electron ELaNa 19 launch?
Here is a GIF that I made of the recent Electron Launch from frame grabs in the Rocket Lab video ELaNa 19 Launch - 12/16/2018 It is about 4M, so it won't fit in SE's normal image import.
Frames are ...
4
votes
0answers
75 views
Why doesn't a regeneratively cooled engine crack due to differential expansion induced by thermal gradients?
A liquid rocket engine with regeneratively cooled chamber walls and nozzles would definitely be one among those components experiencing the steepest thermal gradients (Chamber wall inner - $3000 K$ ...
4
votes
1answer
364 views
Are there rocket nozzles that use non-elliptical shapes?
I was reading this question: Why the non-symmetric design of rocket nozzles?
Which got me thinking, have there been any nozzles that don't end in an ellipse? Even the one in that question ends in a ...
2
votes
0answers
324 views
Why is SpaceShipTwo's nozzle scarfed? [duplicate]
As seen in this photo (from here) there appears to be a significant scarf to the nozzle.
I'm familiar with scarfing reaction control jet nozzles to fit fuselage contours, but this one is completely ...
