Help cooling living H$_2$ fueled pulse jet engine
A squid-like organism uses gravity powered flight but relies on jet propulsion for launch, pouncing, and evasive tactics.
It's aerodynamically based on the way a true squid flies however it has evolved atmospheric jet propulsion to replace the constricting hydraulic jets.
It's tentacles and fins have become much larger for sustained flight, but it's arms remain articulate for grappling and marine locomotion.
The jet deflagration chamber is the scavenged nearly perfectly flared cylindrical exoskeleton of another mollusk, with a diameter acoustically tuned to an OH deflagration cycle. This squid binds it to its body, having an intake on the nose and exhaust from the posterior of the animal. The material is unlikely keratin or calcium carbonate, it needs to have good thermal insulating properties and structural integrity.
The jet fuel is twofold: H gas is a natural fermentation byproduct stored in bladders; a symbiotic algae lives in a layer under its translucent skin, consuming its respiratory exhaust and producing O$_2$ which collects in another bladder. The two gasses are injected into the unvalved deflagration chamber for propulsion.
The jet only needs to run for 2-second bursts of possibly 8 - 12 pulses. It's purpose is to simply gain enough momentum to get airborne, or evade a predator while in flight.
Assume the animal's total gross weight is 5kg, and it can accelerate at 8 ms$^{-2}$ for two seconds.
Given the heat generated by this reaction,
What lightweight cooling method can be used to prevent heat damage to the combustion chamber and O$_2$ & H fuel jets?
The cooling method of course should include materials suited for heat transfer and possibly heat removal.
I don't know how much fuel this activity would consume however assume it has evolved 40% efficiency in producing thrust, so 60% is converted to heat, but 80% of that heat is exhausted.
If H$_2$ doesn't have sufficient energy density to generate the required thrust, I'm open to other organically derived fuel options.
This post was sourced from https://worldbuilding.stackexchange.com/q/159389. It is licensed under CC BY-SA 4.0.
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