Anyone have info on Blue Origin's BE-3 engine? All I've found on it so far was presented at NASA's Commercial Crew Program update a couple weeks ago. Slide 17 of this .pdf http://www.nasa.gov/pdf/718299main_CCP-Status-Update-1-9-13-finalSM.pdf. I contacted Blue Origin on Twitter, and they said they couldn't give public timelines for the engine's development. I'd really like to figure out when they will fly it, and on what vehicles they plan to use it.
Also, RL-10 is an expander, and seemed to be fine deep throttling on DC-X. Given that Blue Origin's goal from the start has been an operational DC-X, it wouldn't be surprising if they are using an RL-10 style engine...
Quote from: simonbp on 01/25/2013 08:37 pmAlso, RL-10 is an expander, and seemed to be fine deep throttling on DC-X. Given that Blue Origin's goal from the start has been an operational DC-X, it wouldn't be surprising if they are using an RL-10 style engine...Thats what I was thinking too. The RL10 had a much lower thrust though...
The below paper from Mitsubishi details the open gas generator and expander cycles used on the Japanese LE-5 engines and the use of the open expander bleed cycle on the 300,000-lbf thrust LE-X engine:http://www.mhi.co.jp/technology/review/pdf/e484/e484036.pdf
Have you heard of the Vinci engine? Problem with closed expanders is the your surface expands to the square, while your volumes to the cube. Since the surface is your heat transmition budget and your volume your heat sink requirement, at some point, you simply can't transfer enough heat to expand. I've heard 300kN being the utlimate limit. RD-0146 does about 95kN to 75kN, RL-10 about 100kN and Vinci 180kN. So they are "close to the limit".A benefit of expander cyclers is their reliability. The RL-10 can eat contaminants in the turbo like no other engine.
There is also the third-fluid-cooled cycle.Basically use the heat from the combustion chamber and nozzle to boil water, making steam that turns the turbines.
I believe the RL60 development engine, which used separate expander turbines for fuel and oxidizer, was tested to 60,000 or slightly more.LE-X uses a dual expander cycle, which apparently extracts more energy from the entire combustion chamber/throat/nozzle surface. P/W in the past has said a dual expander could run to at least 300,000 pounds. Wonder if it'd be a good substitute for the J-2X?
Quote from: tnphysics on 01/27/2013 04:53 amThere is also the third-fluid-cooled cycle.Basically use the heat from the combustion chamber and nozzle to boil water, making steam that turns the turbines.Interesting. Has that ever been done before or it it theoretical? It doesn't seem like it would be all that great with the extra mass of the water.
I seem to recall that the V2 graphite steering vanes were hollow, with water inside; water can absorb an enormous amount of energy, and being reasonably dense then a reservoir for 'proper' cooling/turbine power might be surprisingly small and light. It'd be a much nicer turbine working fluid to deal with than High-Test Peroxide, Hydrazine, or whatever.
I don't know much about rocket engines so don't be too harsh on me, but shouldn't it also be possible to cool with the oxidiser in an expander engine? I mean, if there is no preburner, you won't get those corrosive hot oxygen-rich gases, right?There should be much more cooling possible with the phase change in the liquid oxygen. According to wikipedia, the heat of vaporization for H2 and O2 are:(H2) 0.904 kJ·mol−1(O2) 6.82 kJ·mol−1Or, equivalently:(H2) 0.45 kJ·g−1(O2) 0.21 kJ·g−1With a (mass) mixing ratio of say 4.4, you should be able to cool twice as much if you use the oxydiser. Or three times more if you could cool with both the H2 and the O2. Or do I also need to take into account the work done on the turbine axis by the expanding gas? Anyway, is there a good reason not to use the oxygen in an expander?