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Darn. Double post and I can’t find the delete button…

I just ran some numbers with a chamber pressure of 1000PSI, a chamber temperature of 550F, and an exhaust pressure of 25 PSI (slightly underexpanded), here’s what I get (assuming that the stuff entering the nozzle is 100% pure water…   Read more»

The benoulli relation will be relatively useless in this case, since the flow in a rocket motor is definitely compressible (and bernoulli basically assumes incompressible flow). The phase diagram of water is useful though.Oh, and Ken’s suggestion does bring to…   Read more»

Would the pressure between the tank opening and the nozzle not be enough to allow the water to flash into steam? That original picture, its twelve inch section, I was thinking in that distance the water would turn into steam….   Read more»

So if there might be a problem of the water transfering to steam before exiting the nozzle, how can we fix that? should we make the distance between the tank longer so it has more time to change into steam?It’s…   Read more»

Chris,I think what Shredder is getting at, is assuming that all water in the tank has been heated to the gas phase, no liquid in the tank.If that’s the case, the pressure in the tank will be absolutely absurd, as…   Read more»

So if there might be a problem of the water transfering to steam before exiting the nozzle, how can we fix that? should we make the distance between the tank longer so it has more time to change into steam?

I wonder if there is a way to do this with 2 chambers: One containing the liquid, from which the water exits as a superheated liquid, and then a plenum where the water vaporizes due to a pressure drop before…   Read more»

Chris,I think what Shredder is getting at, is assuming that all water in the tank has been heated to the gas phase, no liquid in the tank.Shredder,I believe what Chris is getting at is, with the tank upright and the…   Read more»

Even if the system was laying on its side it shouldnt matter if the nozzle is above or below the container. There should be no air in the system and as soon as the water hits the atmospheric pressure its…   Read more»

Even if the system was laying on its side it shouldnt matter if the nozzle is above or below the container. There should be no air in the system and as soon as the water hits the atmospheric pressure its…   Read more»

Okay, this picture is geometrically incorrect. The system will be pointing downward. Just like an actual motor would be in a rocket, that’s why I was confused. You’re also taking my words to literal; I have no idea of the…   Read more»

Chris,1. Yes the possibility is very high in the steam condensing or cooling off before its exits the system. So testing will have to be done to make sure we do get the water hot enough so it keeps above…   Read more»

Hey be nice…..

Chris, have at it! There are so many falsehoods in Shredders’ post…

Chris,1. Yes the possibility is very high in the steam condensing or cooling off before its exits the system. So testing will have to be done to make sure we do get the water hot enough so it keeps above…   Read more»

Chris, you are dead-on in everything you’ve said. A “steam engine” emits gas not water (regardless of temp). Otherwise, it is a bottle rocket (and, not the fireworks kind), i.e., not taking advantage of the con/div nozzle, although the “bottle…   Read more»

This seems like a really interesting idea, but I do see a couple of problems.1) You’ll need to get the water EXTREMELY hot, since when it flashes to steam, it also cools substantially (energy is absorbed by the phase transition)….   Read more»

Firstly, I would consider a “burst disk” instead of a valve. They are available in precisely calibrated pressure ratings and were extensively used in Apollo and in other expendables for a wide variety of purposes.A resistive heater would probably be…   Read more»

Were not actually trying to put it in a vehicle and attempt a launch. We were going to make a test stand for it so we could get data off of it. We looked at solenoid valves, some of them…   Read more»