Everyone knows the trick to keeping a candle flame out of a balloon – adding a little water before the air to absorb heat from a relatively cool flame. So [Integza]In his quest for 3D printing, a jet engine wondered if the same principle could be applied to a 3D printed combustion chamber. First, the small pond of water was replaced by a pumped stream from an external reservoir, giving the thin plastic inner surface at least a vague chance of survival. While this whole plan may seem quite unrealistic (although we admit, if you have watched any other videos on the channel recently, not so much) the idea has some merits. Combustion jackets are used in many rocket engine designs to cool liquids, we think, the German WWII V2 rocket has used this concept with much success. After all, some materials only soften and become structurally weak when they are hot enough anywhere, so if they are sufficiently conductive, the excess heat can be removed from the outer surface and keep the surface temperature within a sensitive range. Since the resin is a thermoset plastic, and will burn instead of melting, this behavior will be different, but not necessarily good for this application.
The problem we are seeing is the thermal conductivity of the resin wall, balancing with the cooling rate from the flow of water, while making it thick enough to withstand the pressure of combustion and any shock material. Quite a complicated task if you ask us. Is resin the right material for work? Probably not, but it’s fun to find out anyway! At the end [Integza] Managed to come up with a design that, with the help of a metal injector separating plate, survives long enough to maintain some kind of combustion, until the plate becomes overheated and the resin burns around its support. Good luck next time!
This is not the first attempt to use 3D printed resin for such an application, here it is an attempt to use an air-multiplier type setup with a combustion chamber. Of course it is much wiser to make a combustion chamber from a toilet roll holder, just like [colinfurze] To be sure, people at home don’t try it!