Modeling heat transfer in a Hybrid rocket engine combustion chamber

[SpideyWebb]

Hi! I am new to thermo design work and am really hoping to just get pointed in the right direction. I am in a group that is attempting to design a 6061 aluminum combustion chamber for a hybrid rocket engine. This will be a prototype design just to get things going on the test stand, weight is not a concern. The engine will fire for about 7 seconds, and I am wondering how I would go about modeling a high temp and pressure flow condition over this period of time. Bottom line is we want to know if we can get away with using aluminum for this purpose (will it melt completely? will material properties change drastically under these conditions?) I have access to the Solidworks Flow sim package, but I have a feeling that is not going to be too helpful with this sort of analysis. Any suggestions for resources/reading/flow sims (preferably free) would be very much appreciated

Thank you

 

[Compositepro]

Aluminum is unsuitable. 6061 loses much of its strength at 400F. Powdered aluminum is a common ingredient in solid rocket fuel.

 

[SpideyWebb]

Appreciate the response. If we were to switch to something like 304 SS, what would be the approach to making a simple model for this? Is it significant that the fire time is relatively short?

 

[MJCronin]

Aluminum has been used in Rocket nozzle components .... but only if it is a regenerative liquid cooled design.

https://en.wikipedia.org/wiki/Regenerative_cooling_(rocket)

While stainless can tolerate a higher operating temperature than Al, without a pumped liquid cooling system, it too will fail.

https://www.quora.com/Why-isn-t-stainless-steel-used-in-rocket-engines

MJCronin
Sr. Process Engineer

 

[SpideyWebb]

How can I reach these conclusions myself using theory? I want to make a simple model (without liquid cooling) with inputs being material properties and combustion/fluid properties, output being the state and properties of the material after firing.

 

[davefitz]

I think that you may be reinventing the wheel. You may want to research the papers published in the 1960's on this subject, nad related NASA papers. My guess is that they used titanium with an ablative coating for short term firings.

"...when logic, and proportion, have fallen, sloppy dead..." Grace Slick

 

[MJCronin]

Your Welcome ....


MJCronin
Sr. Process Engineer