12 votes

Is it always one nozzle per combustion chamber and one combustion chamber per nozzle?

Partial answer: This engine from the 1970s vintage Viking Lander is a liquid engine featuring one combustion chamber and many nozzles. (you can ignore the red arrow, it's from another question). The ...
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10 votes
Accepted

What is the job of the acoustic cavities inside the main combustion chamber?

They are provided to help damp out combustion instabilities. The main injector uses cooled baffle elements, developed at Glenn in the 1960s to control pressure waves that could destroy the engine....
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10 votes
Accepted

Does peroxide spontaneously decompose when introduced into hot combustion chambers?

HTP will sustain a combustion reaction without a catalyst once ignited, but it's not clear to me if the reaction proceeds quickly and smoothly enough to be a good idea for rocket combustion chambers. ...
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8 votes
Accepted

Is there a distinct flame-front in a liquid-fuelled rocket combustion chamber?

Partial answer because based on a simulation doesn't address the secondary question about changes with throttling The paper CFD SIMULATION OF A LIQUID ROCKET PROPELLANT (LH2 /LOx) COMBUSTION CHAMBER ...
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7 votes

How are rocket propellants ignited repeatedly without the ignition source melting

Restartable hydrogen-oxygen engines like the RL10 (used on the Delta and Atlas upper stages) and J-2 (used on Saturn) use spark ignition. On the J-2, the spark igniter is positioned above the fuel ...
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7 votes

Does LOx stay as liquid when entering combustion chamber?

For most rocket engines the fuel is used as nozzle and chamber coolant, which heats it up. It may enter the combustion chamber as gas or liquid, depending on design. But the LOX is merely pumped to ...
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6 votes

How to calculate these engine parameters on my own?

Anton must really love chemistry or pain. NASA's CEA is a robust tool for analyzing combustion thermo-chemistry which was developed by the same Gordon & McBride mentioned in Anton's answer while ...
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  • 1,374
5 votes
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I don't know where to start with the calculations - rocket engine

The reason you can't finish your calculations is that you are missing half of the engine. You are going to have to make some decisions about the nozzle in order to get exhaust velocity. I'll make some ...
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5 votes
Accepted

How are the combustion chamber length and diameter decided

You can referthis book Modern Engineering for Design of Liquid-Propellant Rocket Engines chapter 4. It depends the on the number of performance parameters such as $C_f, C^*$ and $I_{sp}$. From which ...
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  • 1,161
4 votes

How is a desired chamber pressure achieved in a liquid rocket engine

I'll make an attempt at this although it seems unclear whether you're asking (a) the theoretical ramifications of a certain chamber pressure or (b) the thermal and mechanical aspects of making it ...
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  • 505
4 votes
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What Constitutes A Combustion Chamber?

'tubes' aren't enough. You want an injector, in order to atomize the fuel and oxidizer and mix them. A simple one is the pintle injector, which has concentric openings for the fuel and oxidizer. ...
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4 votes

Is presssuized gas absent in a turbopump-driven rocket engines?

The ACES upper stage (in development at the moment) is being designed to do without an external source of pressurizing gas: Fundamentally IVF is a Hydrogen/Oxygen auxiliary power unit, that uses ...
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  • 122k
4 votes

Is presssuized gas absent in a turbopump-driven rocket engines?

No, the Centaur with its RL-10 engines requires tank pressurization. Helium Supply and Pressurization System - Helium is the main pressurant used for tank pressurization. Typically, four 26-inch ...
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4 votes

What is the effect of poorly choosing L* in combustion chamber design?

From my (probably) similarily rough understanding of L*, it's a minimum size required for propellants to stay long enough in the chamber to mix properly. If the distance is shorter than that, you will ...
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4 votes

Is it impossible to prevent the combustion instability by injecting the reactants at the choking condition for the liquid rocket engine?

To an old timer like me who was one of the pioneers in much of the rocket engine research during the Saturn V F-1 engine development at Princeton University (around 1966 – 71), I’m glad to see renewed ...
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  • 167
3 votes
Accepted

How to calculate these engine parameters on my own?

You will need to write a solver for the incomplete combustion of your propellant. This can be done by hand, but I recommend writing a program to implement it. These days, such calculations are ...
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  • 10.1k
3 votes

For F1 rocket engine, why propellant holes were not in proportion to the fuel to oxidizer ratio?

There are different numbers on this NASA page about Saturn V: Finally, the fuel squirted through 3 700 orifices into the combustion chamber to mix with the oxidizer, which entered through 2 600 other ...
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  • 47.3k
3 votes

If building a liquid propellant rocket engine, with bi propellants, how does the dimensions of my Combustion chamber, affect the efficiency?

Think of it in terms of providing enough residence time for the propellants to vaporize, mix, and burn to completion. Since most of the flow is axial, the length of the chamber contributes more ...
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  • 557
3 votes
Accepted

Is there a relation between combustion instabilities and chamber pressure?

I'm not going to do this beautiful beast of a paper justice, so by all means, feel free to dig into it yourself. It actually looks pretty readable, although processing all the math and theory would ...
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3 votes

Is it always one nozzle per combustion chamber and one combustion chamber per nozzle?

I would note that the RD-170 and RD-180 designs, while they appear to have two nozzles and two combustion chambers in the assembly, are said to perform as one because there is a pipe from one chamber ...
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2 votes
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Discrepancy in local Mach behavior between CEA and other sources

The primary mechanism for your error is likely the assumption of constant $\gamma$ (specific heat ratio) in the isentropic flow equation you listed. In an equilibrium calculation, the composition of ...
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2 votes

How does one determine the optimal CH4:O2 ratio in a methane-LOX rocket engine?

This doesn't have a simple answer. From a pure chemistry standpoint you can observe that one CH4 molecule will completely react with two O2 molecules. CH4 has a molecular weight of 16, O2 has a ...
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2 votes

What is the inner wall of the thrust chamber made of?

Inconel is chosen because it has a much higher melting point than copper, so the engine can be run at a high temperature.
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