Liquid restartable engine - how it work ?

[killium]

I am talking about the fuel in the tank. When a spacecraft is in orbit, for example, and it restarts its engine, how does the fuel goes into the engine ? In a weightlessness environnment, the liquid fuel will be dispersed everywhere in the tank, not necessarily in front of the "intake". A turbo pump as to be "primed", what if there is no fuel at the entrace of it ? Even with a pressure feed systems, you would have some of the gas used for pressurizing going into the engine... not very good!<br /><br />So how does it work ? <div class="Discussion_UserSignature"> </div>

 

[heyscottie]

A very good question! I'd never thought of it before.<br /><br />I'd like to clarify on method 1 -- are you describing a tank with gas on one side of a sliding bladder and fuel on the other? As the liquid fuel is used, gas is pumped into the other side of the tank, and the bladder is pushed against the liquid, keeping a tight seal, and disallowing any gas entry.<br /><br />If that's what you were describing, I guess I would consider that the more obvious method. Using a fine screen and relying on surface tension seems to be a more genius-like approach.<br /><br />Under what situations do each approach seem to work better?

 

[killium]

Yes SG thank you ! I knew i was on something <img src="/images/icons/wink.gif" /><br /> <div class="Discussion_UserSignature"> </div>

 

[heyscottie]

Thanks for the response, and the correction to "propellant". I guess I had assumed that the oxidizing agent would have been stored in a separate tank and was combined with the fuel only at the nozzle, which would have made "fuel" a more accurate term.<br /><br />But why are the fuel and oxidizer stored together? That seems to be suboptimal to me.