Louisa Tchaicha (asker) Jul 17, 2012:

@Chris Ah I see, thank you so I don't need to be so precise in patents? I put "outlet speed" (and sent it) :) I think I'd rather not know if it's not ok :((

chris collister Jul 17, 2012:

@loulou horses for courses: if you take the sun, for instance, no-one refers to coronal mass outlets, with "ejection" being the abstract noun of choice. Unless I'm mistaken, your links refer to the very ingenious "pop-pop" boats I used to play with as a boy, and which still embody some baffling physics to this day. The fluid *ejected* by the exhaust is mostly water, which propels the boat forward, much like a rocket motor. I don't think it really matters whether you use flow, outlet or ejection, as the informed reader will know exactly what you mean.

Louisa Tchaicha (asker) Jul 17, 2012:

@ Chris and Salih I found "vitesse d'éjection" (des gaz) to be "outlet speed" in english, on this site, here are the english and french versions:
http://www.eclecticspace.net/poppop/jy/moteur_pop-pop_V2.pdf
http://www.eclecticspace.net/poppop/jy/pop-pop_engine_V2.pdf

Louisa Tchaicha (asker) Jul 13, 2012:

oops and @ Chris I did not put the term I was looking for!! it's "vitesse d'éjection" sorry! :(, I found "vitesse d'ejection" to be effective exhaust velocity in the link I pasted in teh question
Chris, I have teh translated abstract and "écoulement de gas "is translated as "gas stream"

chris collister Jul 13, 2012:

It's rocket science...! Picking the title apart (presumably a patent), it is, in fact, exactly as it says. In translating patents, literary merit may justifiably be sacrificed for accuracy. Rocket thrust (I assume that this is wat the subject is) depends on the density of the gas being ejected and on its velocity, though generally the latter is constant, the overall thrust being controlled by pulsing the flow. Hence the need to control (moduler) it precisely. Eg. A device for controlling the mass flowrate of ejected gas. I think "ejected" is a legitimate translation of "écoulement" since the context justifies it as such.