Southwest Research Institute engineers are developing a cooled, radial gas turbine for a small generator that provides thousands of hours of electricity to an unmanned aerial vehicle (UAV), a significant improvement to current UAV turbines that only operate a few hundred hours before wearing out.
Turbines are rotary mechanical devices that, when combined with a generator, produce electrical power.
"This turbine is part of a generator that's similar to what the average person might use to generate electricity in their home when the power goes out," said David Ransom of SwRI's Mechanical Engineering Division. "The version we're creating is more compact and efficient, tailored to the needs of a small, unmanned aircraft."
The problem with current small turbine models is that during the generator's combustion process, the turbine is constantly bathed in high temperature gas that ultimately damages or destroys it.
"The hotter the turbine gets, the better its performance," Ransom said. "But these smaller turbines can't survive the temperature, so we've designed one that has tiny airflow passages that cool the turbine without sacrificing the power of its performance. Normally with small turbines you have to make a choice between performance or reliability, but we're making it possible to have both."
SwRI has worked with internal passages of high temperature turbines on large version used in power plants and passenger airplanes. To create the small, intricate design with internal air passages, engineers are using a new selective laser melting (SLM) machine, which builds metal parts layer by layer. The new SLM machine, which arrived at SwRI in December 2017, sets itself apart from other 3D printers in that it's built to craft layered and highly detailed metal parts rather than plastic ones.
[...] "Generators that provide power to us and to big aircraft already have cooled turbines, whereas a generator of this size for a small craft does not," Ransom said. "It's an exciting engineering challenge, and having the ability to print parts with the SLM machine is a real advantage."
(Score: 3, Insightful) by mhajicek on Monday September 10 2018, @10:54AM
The airflow passages are industry standard, but usually the turbine blades are cast and any holes not cast in are EDM'd.
The spacelike surfaces of time foliations can have a cusp at the surface of discontinuity. - P. Hajicek
(Score: 4, Funny) by requerdanos on Monday September 10 2018, @01:50PM (8 children)
Emphasis added:
The average person is going to generate his electricity chemically by suspending dissimilar metals in a bath or paste of electrolytes* [batteryuniversity.com] when the power goes out.
The occasional average person might, with small probability, have a gasoline or diesel small engine turning a magneto to generate electricity.
The average person is not, repeat not, going to have any device whatsoever that uses a turbine in any way to generate electricity for "when the power goes out".
That average person only "uses" a turbine in the sense that they buy electricity from a provider who might use a turbine or two at their generating stations. But when the "power goes out", they aren't using the turbine any more.
I mean, what the heck? How do you get to be this removed from reality and still be a mechanical engineer?
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* Yes, Brawndo does have electrolytes, but the solution is not sufficiently concentrated to produce much electricity. Works much better than toilet water, though.
(Score: 0) by Anonymous Coward on Monday September 10 2018, @03:35PM (7 children)
Reading comprehension, man.
That doesn't say the turbine is similar to what the average person might use; it says the generator is similar. And two things can be similar in lots of ways even if one has a diesel engine and the other has a turbine.
(Score: 2) by requerdanos on Monday September 10 2018, @04:05PM (6 children)
If your generator's only similarity to your typical home model is that it uses moving magnets to make electricity, then it's also "similar" to the sun's magnetosphere.
I.e., not remotely.
(Score: 2) by aristarchus on Monday September 10 2018, @04:13PM
What an interesting article! What is a "turbine", again? What if I do not want to generate electricity, and instead just appreciate impelled radial motion for its own sake? Why do the words "3-D printing" make people into maroons?
(Score: 0) by Anonymous Coward on Monday September 10 2018, @04:22PM (4 children)
Okay, but do you have some reason to believe that's the only similarity, or are you just being silly on purpose? Possible similarities that come to mind include similar mechanical and electrical power, similar load characteristics, and similar control systems (more-or-less a simple RPM-governor).
(Score: 2) by Osamabobama on Monday September 10 2018, @04:37PM (3 children)
You are completely disregarding the massive differences between the Otto cycle and the Brayton cycle. The former has constant volume heat addition, while the latter has constant pressure heat addition. To assert similarity between two generators working with these two completely different thermodynamic processes is to be deliberately obtuse.
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(Score: 2) by deimtee on Monday September 10 2018, @09:28PM (2 children)
To be pedantic, neither generator uses either cycle. The engines that drive the generators do. It is possible (but unlikely) that the generators are identical except for some gearing to adjust the input rpm.
200 million years is actually quite a long time.
(Score: 2) by Osamabobama on Monday September 10 2018, @10:14PM (1 child)
I suppose that means it's time to hash out the semantic subtext of this discussion. It's almost as if we are pretending that the word 'generator' has only one precise meaning and that the other guy must be confused about something else, based on how he used that word. That meaning is, of course, a component that turns rotary motion into electrical current. Those of us wise in the ways of technology realize, as well, that a generator needs a prime mover, such as (in this case) a piston engine or a turbine engine, without which it will not function. To speak of a turbine as a part of a generator is ridiculous, and indicates a gross misunderstanding of how things work.
However, there is an equally acceptable meaning for 'generator' that has been in use for decades, and that meaning refers to the entire assembly whose function is to output electrical power. These may be more precisely referred to as motor-generators, or turbo-generators, but the lack of precision doesn't negate the overall meaning. For these items, the prime mover is a component of the whole. This is the meaning used in the article's quoted summary.
I realize that being pedantic can be fun, and I had fun with my earlier comment that intentionally misunderstood the prior comments, but now I find myself wondering if the discussion of the improved thermodynamics would have been further along had we all just skipped it.
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(Score: 2) by requerdanos on Monday September 10 2018, @10:39PM
The mechanical engineer in question in explaining the relevance of his work by basically saying that "this thingy can be connected to a generator which is like a generator" in broad terms (redundant nonsense) and "this device attaches to a generator, and that generator is itself like a generator very, very specific but completely unrelated in kind, size, design, and application" in a more specific sense (just nonsense).
Either way it's sleight-of-mouth that pulls any discussion away from the device or its relevance, and explains it in terms that are less useful than even "Libraries of Congress" or "school buses" or "elephants" or "typed double-spaced sheets of (letter/A4) paper" which at least are units of measure, to a degree.
And I agree, it's hard to say whether just letting nonsense flow right by vs. saying "hey, that's nonsense" improves a given discussion. I think the edge often goes to having the ancillary discussion about whether the nonsense itself furthers the original discussion. My position is no (I think it distracts and distorts), others have responsible opposing views.
(Score: 4, Interesting) by richtopia on Monday September 10 2018, @04:44PM (2 children)
Building turbine blades is tough. Turbines operate in severe conditions demanding tough materials and the complex geometry is very difficult to make with traditional machining. Turbines are often used as demonstration parts for 5 axis milling machines or 3d printers.
The actual article is discussing more on the novel design of the turbine (using SLM for turbine construction as mentioned in the summary is not new). I hope the new design is successful; I was at the Evergreen Aerospace Museum this week and I remember seeing a small gas turbine engine. It was not expected to be successful during design (in the 50's) because everything was being scaled up at the time, but the engine was hugely successful as smaller helicopters are a very real market segment. UAVs will take that even further; without a human UAVs can be further optimized for more specific applications like extended flight time.
(Score: 3, Funny) by bob_super on Monday September 10 2018, @07:21PM (1 child)
> without a human UAVs can be further optimized for more specific applications like extended flight time.
Can we keep designing them with small fuel tanks, just so we get a chance to move around while the killer robots are refueling ?
(Score: 0) by Anonymous Coward on Monday September 10 2018, @10:01PM
So what is the flight duration time for a gasoline powered quad-copter remote controlled toy aircraft, vs. a battery-powered one? Would this not be a poor efficiency to transform the chemical energy of the petrol into electricity, just to spin rotors?