SpaceX's New Combustion Technologies 132
An anonymous reader shares this story that takes a look at some of the advances SpaceX is working on. "Getting a small group of human beings to Mars and back is no easy task, we learned at the recent GPU Technology Conference in San Jose hosted graphics chip and accelerator maker Nvidia. One of the problems with such a mission is that you need a very large and efficient rocket engine to get the amount of material into orbit for the mission, explained Adam Lichtl, who is director of research at SpaceX and who with a team of a few dozen programmers is try to crack the particularly difficult task of better simulating the combustion inside of a rocket engine. You need a large engine to shorten the trip to Mars, too....Not only do you need a lot of stuff to get to Mars and sustain a colony there, but you also need a way to generate fuel on Mars to come back to Earth. All of these factors affect the design of the rocket engine....As if these were not problems enough, there is another really big issue. The computational fluid dynamics, or CFD, software that is used to simulate the movement of fluids and gases and their ignition inside of all kinds of engines is particularly bad at assisting in rocket engine design. 'Methane is a fairly simple hydrocarbon that is perfectly good as a fuel,' Lichtl said. 'The challenge here is to design an engine that works efficiently with such a compound. But rocket engine CFD is hard. Really hard.'"
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The same issue is a challenge to internal combustion engine design and a number of other applied physics problems. Combustion is a chaotic process and thus a hard challenge for computational modeling. Developing better simulators for combustion would reduce the cost of developing reliable and safe systems.
Re:It is (Score:5, Interesting)
I hope they simulate propane too, not just methane. Propane has some really interesting properties as rocket fuel but have (like methane) never gotten much research. But now there's a big rush to research methane as fuel based on the concept of generating it on Mars - so propane still gets left in the dark.
Methane's ISP is only very slightly better than propane's - 364,6 vs. 368,3 at a 100:1 expansion into vacuum and 20MPa chamber pressure. But propane at around 100K (note: not at its boiling point, 230K) has far higher density (782 kg/m^3), closer to that of room temperature RP-1 (820 kg/m) then that of boiling point methane (423 kg/m^3), which reduces tankage mass and cost. 100K propane's ISP is of course better than RP-1's 354.6 in the same conditions as above. Plus, its temperature is similar enough to your LOX that they can share a common bulkhead, which reduces mass further and simplifies construction.
Hydrogen generally is the easiest fuel to synthesize offworld. Methane is generally second, and propane third. Hydrogen is often rejected as a martian fuel because of the tankage and cooling requirements. Methane can be kept as liquid on Mars with little cooling in properly designed reflective / insulated containers - but so can 100K propane, in similar conditions, but with significantly smaller tankage requirements.
It seriously warrants more research, I tell you what.
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So I think we've found Hank Hill's /. account.
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Very insightful. It would seem that you could build a simple processing facility to distill out propane from the hydrocarbon muck. Yeah would need a similar facility for purified methane anyway, so what's the diff? Not much.
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I'm an employee with Bagaveev Corporation. We're a very small startup that is developing a launch vehicle for nanosatellites. We've designed our engines for propane from the start. The higher density of RP-1/LOX is offset by propane's higher ISP and the ease of a shared bulkhead. It's surprising that more people haven't done any serious development with propane; I guess there is a lot of inertia in the choice of RP-1 as a rocket fuel which prevents people from trying other fuels unless absolutely required (
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Wow, this is great to hear - I'd never heard of you guys before. :)
And looking at your site, I like what you're doing even more - direct 3d printed aerospikes? Pretty darn cool. What sort of 3d printing tech are you using? Have you looked into the new hybrid laser spraying / CNC system that's out there (I forget the manufacturer)? The use of high velocity dust as source material gives you almost limitless material flexibility and improved physical properties that you can't get out of plain laser sintering,
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Air launch usually isn't so much about the (small) extra delta-V as it is the greater flexibility on launch sites. Which is why I asked as to whether you have an equatorial site. :)
I'll definitely keep my eyes out! :)
They don't know what "hard" is. (Score:5, Funny)
They think what they're doing is "hard"? What the hell do they know? I once had to scale a Ruby on Rails web app so it'd handle more than 8 requests per second. Let me tell you, that makes fluid dynamics and rocket engines and trips to Mars look easy-peasy!
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Hmm.. systemd in ruby on rails.. Interesting concept but I don't think to many people will like it. Instead, they should just try the windows really good version. there is an online demo here but it relies on flash.
http://www.deanliou.com/WinRG/ [deanliou.com]
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I'd like to see that with Silverlight....
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FTFY: implementd systemd
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Spacex Barbie says (Score:2, Funny)
Re:Spacex Barbie says (Score:5, Funny)
It's not exactly brain surgery, though.
https://www.youtube.com/watch?... [youtube.com]
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It's not exactly brain surgery, though.
https://www.youtube.com/watch?... [youtube.com]
Hil-freakin-larius! Love it.
I always thought the orbital mechanics were the toughest part of getting about in space. But all of it fun.
Wrong Focus (Score:4, Insightful)
It's time to stop jetting around the solar system on chemical rockets. Designers and funding should be directed towards lofting and running multi-megawatt reactors. They would be used to power multiple ION engines [space.com] and once at the destination, provide power.
Re:Wrong Focus (Score:5, Insightful)
You cannot leave earth or mars surface using an ion engine.
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True 'nuff, but for interplanetary missions there's no off-the-shelf tech to beat it. As Clarke said, "Once you're in LEO you're halfway to anywhere..." (or was that Asimov... or Heinlein?).
The thing about SpaceX is they're planting a flag on Mars now, and working back from there to define their technology. Their MCT (Mars Colonial Transport) engine class is spec'd to run on methane, since it's fairly simple to create this fuel from available resources on Mars. Nobody would be working on methane-fueled rock
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Nobody would be working on methane-fueled rocket engines if they didn't have a long-term goal of colonizing Mars.
Or they might have invested heavily in cattle ranches a la Thunderdome [imdb.com] in order to leverage a source of Methane that is currently going to waste.
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Which no doubt explains "Rendezvous with Rama" and 2001:a Space Odyssey"....
Clarke was enough of a scientist to know that we don't know the limits of the "possible" quite yet....
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*Sigh*...yes. I and everyone else knows that. Thus the "...around the solar system..." comment.
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The article is mainly talking about improving the technology to take off from earth and mars, so how is this the "wrong focus" ?
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Not today. But maybe in the future. If you can develop a crazy-power-dense energy source and cooling system, you could probably do it with a MPD thruster. The research I've seen on MPD thrusters operating in pulsed mode yields crazy output relative to the mass of the thruster. But you can't run it continuously because it'd overhead and take way too much power. But who knows about the future? There's the potential for extreme heat conductors like isotopically pure diamond, maybe a some kind of fission fragm
sure u can (Score:2)
just make sure you have a huge chem rocket engine firing at the same time...and you can leave orbit using an ion engine, a steam engine, or a bunch of hamsters.
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Nonsense. They scale at least linearly, which is "good enough for gub'mint work" as the saying goes. I follow the "space" space fairly closely, and I've never heard anything about ion propulsion suffering from "scaling" problems. If you have sources for this, please cite them. As an avid enthusiast, this is the kind of information I crave above all.
Comment removed (Score:5, Informative)
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Back in the 80's I was still running DOS. So, Windows 10 should be impossible now, right?
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I believe YOUR analogy was, "We couldn't do it in the 80's so we can't do it now".
THAT'S stupid.
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A particle beam weapon is very similar to an ion thruster.
One difference is that the beam weapon has to neutralize the exiting plasma's charge to keep the beam from spreading. Not an issue for a thruster. Of course that means the ship will develop a pretty good charge.
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Why did you write "ion" in all caps? It's not an acronym.
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Because I have not pried off my fucking Caps Lock key on this laptop yet.
Re: Wrong Focus (Score:2)
The Gravitational Constant on Mars is about 1/3 of Earth's.
Why won't a really good ion ASSIST engine work?
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Because an ion engine is not just 1/3 as powerful as a liquid fuel engine, it's in the order of 1-10 million times less powerful than a rocket engine. If you compare a ASSIST (which isn't the most powerful nor most efficient ion thruster system) with a F9, it turns out a F9 engine (5,885kN) is 65 million times more powerful than an ASSIST system. The thrust-to-weight ratio for ion thursters is waaaaaay below 1.
Re: Wrong Focus (Score:5, Informative)
The gravitational constant is G, and is the same everywhere...it's a physical constant. The surface gravitational acceleration of Mars is different because of its lesser mass. And apart from the problem of the atmosphere, having surface gravity of about 1/3 of Earth's is nowhere near enough to make ion propulsion useful for launch, an ion propulsion system with a nuclear reactor and propellant would easily weigh around ten thousand times what it could actually lift on Mars. The only bodies where launch could be usefully performed or assisted by ion thrust are asteroids and comets.
Ion engines use very high amounts of power and very low flow rates of propellant. They provide a benefit when you need low amounts of thrust for a long period, and have either plentiful solar power or a nuclear power source. They could be used for shipping bulk supplies ahead of a manned expedition, but a manned expedition itself or any other mission with tighter than usual time constraints will use chemical propulsion, or at most nuclear thermal propulsion. These relatively low-Isp systems require more propellant for a given delta-v, but can achieve accelerations millions of times higher than ion engines, and do so without heavy power systems and gigantic radiators.
Re: Wrong Focus (Score:2)
Yeah, I was catfished by some websites and got suckered into that godawful mistake.
Has anybody a better term for Gravitational Acceleration Constant of planetary bodies, other than G-Force?
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The gravitational acceleration of an object isn't a constant at all, it is a function of distance. The relevant "constant" is the "standard gravitational parameter" (should be Greek mu, broken in the preview) = GM, the product of the gravitational constant and the mass of the body. This can be directly measured more precisely than G or M (G being very difficult to measure precisely, and measurements of M generally being derived from measurements of ) and is far more commonly needed in calculations than G o
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I am under no illusion that I just miraculously thought of something no one else has.
It's more of a "quit mucking around with chemicals and focus on what has long term potential."
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Chemicals aren't going away. They have too many advantages in thrust to weight, cost, controllability, etc.
SpaceX is in the business of launching stuff to orbit, and bringing boosters and spacecraft back down to planetary surfaces. Ion engines aren't going to do that...exactly how would you suggest they deliver those reactors and ion propulsion systems into orbit? Their focus is right where it needs to be.
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Don't forget the multi-megawatt radiators needed to provide a cold sink for those reactors. Chemical rocket engines dump heat into the exhaust gases but in a vacuum radiators have to be huge and heavy to get rid of significant amounts of heat from something like a nuclear reactor. They also have to be shaded from sunlight to stop them absorbing heat...
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Don't forget the multi-megawatt radiators needed to provide a cold sink for those reactors. Chemical rocket engines dump heat into the exhaust gases but in a vacuum radiators have to be huge and heavy to get rid of significant amounts of heat from something like a nuclear reactor. They also have to be shaded from sunlight to stop them absorbing heat...
There is always Nuclear Thermal Rockets [wikipedia.org] which pour the reactors heat into the propellant.
Re:Wrong Focus (Score:4, Insightful)
A NTR requires the reactor core to be hotter than the exhaust gas stream/propellant in order to transfer heat to it. Anything over 4000 deg K, structures in the core are going to melt and that would be bad, and that limits how hot and how fast the exhaust will be.
Nuclear thermal is more efficient than chemical rockets but not that much more efficient. It can use readily available mass like cometary or asteroidal ice or gases like methane mined from Titan but if you have access to such sources then simple cryogenic fuel/oxidiser combos like LOX/LH2 produced from ice by solar-powered electrolytic plants are going to be easier to manage and less massive than a reactor-based rocket motor. In such a case the vacuum of space works to your advantage to keep the LOX and LH2 from boiling off too fast.
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No, even if the battery didn't weight anything, the thrust of ion engines in measure in milli-Newtons, so they wouldn't even be able to lift themselves.
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Not true. Look up MPD thrusters. The thrust to weight ratios are incredible, the only limiting factors are cooling rate and power supply. If we're proposing an "infinitely powerful battery", then that takes care of the bigger challenge. A MPD thruster with such a battery and, say, an isotopically pure diamond radiator, could conceivably lift off from the surface of a planet.
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My personal "dream rocket" is to combine a dusty fission fragment rocket with the nuclear lightbulb concept. You have a subcritical fast dusty core which achieves criticality via a spallation neutron source rather than a moderator, using a compact linear accelerator powered by the reactor's fragment deceleration grids (no Carnot losses). The core radiates intensely in the mid-IR range. The core is suspended electrostatically in a fused silica chamber, which while it will steadily blacken in the visible from
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This is a really interesting idea - you have any recommended reading on the topic? Any work you are aware of pursuing this kind of technology?
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The cornerstone of it is the dusty fission fragment rocket [rbsp.info], so I'd start there. Another key aspect is the use of a accelerator-driven subcritical [wikipedia.org] fast reactor [wikipedia.org] rather than a critical slow reactor. Lastly it's a variant of a nuclear lightbulb [wikipedia.org], albeit (as mentioned) without the primary drawbacks of them (containment and radiation blackening of the chamber blocking the light). This latter aspect is due to the spectrum changes [osti.gov] of fused silica (I can't find a paper on short notice that shows the IR spectrum, but
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Note that it's technically possible to have something like this with a slow reactor; you could for example use steam as a moderator, which will transmit a reasonable proportion of near infrared through it (the hotter you can run your fuel particles, the better transmission you'll get). But not only will you lose some light, but just the simple act of neutron moderation is a very heat-intensive process, meaning big radiators if you want big power (not to mention that the moderator itself for such a slow reac
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Anything over 4000 deg K, structures in the core are going to melt
At 4000 K, hydrogen molecules have a root-mean-square velocity of 7 km/s. (The relation is v_rms = sqrt(3*k*T/m), where k is the Boltzmann constant, T is the temperature, and m is the mass of one gas particle.) The NERVA nuclear-thermal test rocket reached an exhaust velocity of 8.3 km/s, so I guess they were running a bit hotter than 4000 K.
Nuclear thermal is more efficient than chemical rockets but not that much more efficient.
The space shuttle main engines - an advanced hydrogen-oxygen chemical rocket - reached an exhaust velocity of 4.5 km/s. So NERVA was almost twice as efficient, as me
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You could use a nuclear lightbulb style gas core reactor and either ablation or pure photon drive.
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Yes and no... on the surface of a "planetary" body, you can "sink" the waste heat from your reactor, but in free space, you need acres of surface area to dissipate it. I'm not sure if anyone has ever studied the trade-space between photo-voltaics and space-nukes, but I suspect it would lean toward high-performance PV cells, at least for cis-lunar operations.
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Yes... let's develop heavy power sources in order to power weak propulsion systems - what a great idea! Multiple ones aren't much better, you still need to power them, and you have to multiply a small number (thrust per engine) by dozens (or more) to get a usefully large number (thrust) for any s
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So, when the Wright Brothers were building their plane you were standing their telling them it couldn't be done eh?
Just because there isn't off the shelf technology at the moment doesn't mean we shouldn't strive for longer term solutions to interplanetary travel. Regardless of the propulsion system, having electrical power, lots of it, is the difference between coasting from A to B in a tin can vs something that could actually be called a Ship.
It's all about the physics stupid. (Score:2)
Nope. Unpowered flight already existed by the time the Wright brothers headed to Kitty Hawk, and powered flight was right on the edge of possibility. The drives you propose, aren't. The problem is, you don't grasp that fundamental difference and thus assume that people who aren't as egregiously ignorant as you are the ones in the wrong.
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Solar sails are not new physics.
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Why lift a heavy reactor when you have 24/7 sunlight?
SpaceX has already said it's going to build electric engines anyway. But as someone said below, thats only good for some parts of the journey, you simply need more thrust to take off and land even if they did work in an atmosphere.
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Even a really low-power fission reactor puts out a few megawatts. A few MW of photovoltaics, even in Earth's orbit (and it only gets worse as you head out to Mars) is huge and fragile. Ion engines (or any other form of electric drive) are extremely energy-hungry; the energy demand goes up as the square of the exhaust velocity (E = 1/2 m v^2) and the whole point of electric drives is that they derive their extreme efficiency in terms of reaction mass by using absurdly high exhaust velocity.
There may be a poi
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I assume because sunlight is only 1kW/m at Earth, less at Mars, and of that you only capture a few hundred watts (using very good, ridiculously-expensive spectrolab cells, otherwise only 150-200W or so, assuming full coverage), and space-borne solar panel booms aren't as light as one would desire? If you envision thermal radiators in place of solar panel booms, which can radiate a *lot* more heat per square meter than the couple hundred watts of a solar panel boom, then you can see how a nuclear reactor ha
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The ion technologies we have are nowhere near powerful enough, though. We can't get enough delta-V out of them per unit time to make them useful for human spaceflight. The biggest benefit of an ion engine is that you can use a tiny amount of fuel to get yourself to a high velocity, as long as you have lots of time, and lots of electricity. This doesn't match the needs or abilities of humans in space - humans don't have lots of time, and we don't really need to get them to incredible velocities very efficien
Re: Wrong Focus (Score:2)
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How exactly are radiators that can radiate tens to hundreds of kilowatts per square meter supposed to be mass-prohibitive but solar panels that generate a couple hundred watts at best per square meter not mass-prohibitive? Okay, they're not exactly the same, solar cells are inherently going to be heavier than whatever minimum thin aluminum sheeting is needed for radiating, but the heat pipes leading up to it will be heavier than solar power booms... regardless, I can't see how solar wins this competition.
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Do the math. How hot would a black body have to be to radiate 10 kW/meter?
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Used an online calculator earlier but clearly I had entered something in wrong last time because the results it's coming back with this time are different (and much lower). Tungsten could radiate around 10kW/m around its melting point. Graphite could do 14,5kW/m at its sublimation point. Hafnium carbide, 17,2kW/m at its melting point (though ceramics are brittle and probably not suitable).
An ideal near-term radiative solution for minimizing mass in this regard would involve a working fluid in carbon tubes c
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That's the cold side of your thermodynamic process!
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Wait a minute, no, I entered it right into the calculator the first time around. Argh, this interface [gsu.edu] is confusing. Radiative equilibrium for Tunsten at its melting point 3300C according to the calculator is 92MW/m. A "cool" 1200C radiative temperature according to the calculator 2,6MW/m. According to the calculator, 10kW/m is about 380C.
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K^4 and all.
Ether way, the problem won't be the radiator, it will be the working fluid.
The value of technology investment (Score:5, Interesting)
This is the first article I've seen that explains well how GPUs can/are being used for practical applications along with what can be achieved and some of the issues. Well worth the read even if you're not into this stuff.
I'm sure that there is a significant cost in developing this new approach to CFD (as well as pushing the envelope on GPU operation) but the result is going to be usable for different applications. TFA says there's irony in what SpaceX is doing here as it has applications with automotive Internal combustion engines but I see that as SpaceX/Musk having a secondary revenue stream for this work that doesn't mean he's helping out his direct competitors.
Along with that, they are driving the development of high speed inter GPU communications which I'm sure has value as well.
All this means is that Musk returns to his home planet, not only is the trip going to be fully funded, but he's going to have some money to throw around when he gets there.
myke
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Helping makers of internal combustion engines create more efficiencies certainly does help direct competitors of Musk's.
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This is the first article I've seen that explains well how GPUs can/are being used for practical applications along with what can be achieved and some of the issues.
GPU's have been used for all sorts of "practical" computations for half a decade now, but the really interesting part here is that CFD has been particularly GPU-resistant using existing algorithms. See the Xeon Phi processor, etc. for non-GPU approaches to throwing dedicated hardware at the problem. It's easy to underestimate the enormity of t
Sheesh (Score:2, Interesting)
It's kind of the nature of research that you have to do research. Plus, if you think its hard to design rockets and "rolling your own" CFD models, just imagine how it was when you didn't have the computing power to go beyond the rudiments.
Those troglodytes designing say, the F1 might have had a bit harder of a time designing with limited knowledge and experience than now when can try rolling out likely designs based on good CFD models. Channele
Gamers find Rocket Science is Hard! News at 11 (Score:5, Interesting)
Umm, rocket science is...rocket science?
Combustion CFD is a very difficult area. The problem is that there are so many interlinked phenomena all requiring special modeling methods that one really isn't quite certain of the accuracy of the result unless they can compare it to a physical model test, which is what is frequently done. Simply getting the correct boundary conditions can be very challenging. Failing to apply appropriate modeling and boundary situations leads to a garbage in/garbage out situation, but the numerical solution may look plausibly correct.
CFD is not use exclusively in design work except for very basic cases where the modeling accuracy is well understood. However, CFD for more complicated situations is still useful as it may illustrate behaviors and trends in performance in situations where physical observations are difficult (like in a rocket nozzle). The CFD results can be used to guide and interpret the results of physical testing.
Understanding CFD really requires PhDs who understand fluid dynamics as well as the limitations of the numerical models used. This is true in many industries, not just rocket surgery.
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A little history (Score:3)
A much better and more efficient way to accurately simulate this process can really offer a lot in many areas, not just rocket engines.
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Re:How is it computable at all? (Score:5, Interesting)
All real fluids have a finite Reynolds number, which tells you offhand how much grid refinement it takes to resolve the smallest scale directly. Since for supersonic flow in a rocket engine R is usually stupid high, the small scale turbulence is too small for direct resolution so you resort to turbulence models (e.g. RANS - Reynolds Averaged Navier Stokes) which is in itself an entire industry.
That part is relatively well developed and it's actually approaching the point that (with a team of experts who can recognize the defects on sight) things like CFD wing design are approaching predictive rather than "hey, the CFD actually got it right for a change. Woo!" The challenge for rocket engines is that you're not considering a single fluid, or even a two-phase flow, but a reactive flow which (if you look at all the paths even methane combustion goes through) contains about a hundred components, meaning a hundred flows, with 100 godawfully stiff nonlinear rate equations coupling them - in every single cell! This is the crux that largely stymies effective CFD of combusting flows.
I'm an astrophysics guy so I mostly get to watch from a distance and cringe in horror. We consider ourselves to be Doing Well if we look at gas/dust or neutrals/ions. Really good is looking at neutrals/ions/electrons. We do have our own 100-coupled-rate-equations horror show in examining the nucleosynthesis going on behind a supernova blast front.
The matter of computability is this: Watch a river flow, a prototypical turbulent system if ever there was one. Below the mercurial, ever fluctuating turbulence, you notice persistent, standing structures. Many flows of interest have a similar structure. The flow of water in to a nuclear reactor plenum, air over a car, the atmosphere - Turbulence superimposed on a coherent larger structure. Trying to model the exact turbulence is, as you say, chaotic and pointless: Paths depart exponentially. But if you can model the chaotic part you can still learn about the underlying nonchaotic structure.
In spectrum space, what I'm describing are systems where the turbulence lives in high-wavenumber modes and interacts in some relatively predictable way with the lower wavenumber modes describing the structures of interest. When something breaks down into complete turbulence (e.g. a Rayleigh-Taylor unstable turnover in the atmosphere - Have you ever been in a placid afternoon, then out of nowhere, huge gusts in random directions out of nowhere? R-T overturn), whole new animal...
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You can run many simulations with different initial conditions and verify that they all work correctly with a certain design.
Current Failures Predicted And Will Continue (Score:1)
Last year the National Research Council and National Academy of Science released a damming report on the prospects of the USA or any other country/society on Earth to mount a human space mission to the Moon or Mars. The verdict, 50 years at least and likely 150 years needed. Why? The humans/economy/society/education-training system/infrastructure/GDP do not currently exist and will not, until very likely 150-years from now.
As a matter of economic pragmatism, all current efforts, even writing code, will fail
Why do they need to come back to Earth? (Score:2)
Go to Mars. *Stay there*. Don't return the Presbyterian astronauts back home to Ohio. Keep lobbing supplies at the colonists until they can sustain themselves. Why on earth do we keep trying to re-enact the Apollo fiasco? Colonize, or don't go. Plenty of older folk such as myself who would be glad of a few years of low G before we die while we build up the place for later arrivals. Dying there? The horror! Um, of course you'd die if you stay on Earth anyway. Dying on Mars would be more scenic, and your knee
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Dying on Mars would be more scenic
I suppose if you hate all plants, animals and bodies of water, and prefer a featureless desert where everything is one color.
Old people in a place with no advanced hospital facilities will significantly shorten lifespan, if they can even survive acceleration to earth orbit.
A colony that can't produce wealth can't achieve independence. It would simply be an impoverished dependent colony to support forever.
spam (Score:1)
"Getting a small group of human beings to Mars and back is no easy task, we learned at the recent GPU Technology Conference in San Jose hosted graphics chip and accelerator maker Nvidia.
It hardly gets spammier than that, congrats.
It's not hard when you know sciene and stuff (Score:2)
This guy walks into SpaceX.
Elon Musk says "You here for the interview?"
"Naw... just here to put in the Brawndo fountain."
E
Space X vs ULA (Score:2)
Was ULA making any investment in propulsion technology? Well they started using the Russian RD-180 [wikipedia.org] in 2000 and didn't start looking for a replacement until 2014. This was after SpaceX starting to compete with them for heavy launch contracts and everyone realized that Russia could stop deliveries because of political considerations.
Meanwhile, Space has been continuously investing in new rocket tech
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Hmmm.... US military subsidizing nasa contractors that are also military suppliers to the tune of a billion bucks a year. Hmmm.... is that going to pay for rocket stuff.... or perhaps is there some "off the books" work going on?
Fluid Dynamics (Score:2)
Space X New Combustion Technology (Score:1)
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That's not even the hardest problem they're up against. Generating fuel on Mars is a much more difficult one. As far as we know, there may be no way to produce or find and mine hydrocarbons such as methane. Mars's atmosphere lacks significant hydrogen content. If there's subsurface minable water, that could solve the problem, but only if there's plenty of it.
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Hmm, CH4...so methane is 1/4 H2 by mass, and 3/4 C...
Which means, absolute worst case, that we have to carry the H2 to Mars, thus giving us only a factor of four improvement over having to carry ALL the fuel to Mars.
If, as seems moderately probable, Mars has
Re: Goddard and Von Braun (Score:1)
http://en.m.wikipedia.org/wiki/Sabatier_reaction#Manufacturing_propellant_on_Mars [wikipedia.org]
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Do you get enough extra delta v from converting 4 kilos of hydrogen to 16 kilos of CH4 to make that worthwhile?
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That sounds like an argument for shipping purified methane or some other liquid fuel from Earth.