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Jet Turbine Locomotives
An anonymous submitter writes "I saw this article in the paper today. Not only is it lighter than a comparable diesel engine, it should burn the fuel more completely and be a bit better for the environment. Not to mention it is much faster. They should make more of a point that the North American railway system needs a major overhaul in order to support faster trains." The Department of Transportation has some information about next-generation trains, including a design incorporating a flywheel to improve acceleration.
Union Pacific has a jet powered locomotive. They used to have more, but they burn so much fuel that they aren't very economical to operate. Plus, you can't park them underneath overpasses because the exhaust will melt the asphalt. So they just have the one now and it is mainly used for special loads and public relations.
Smeghead every day of the week.
This may be obvious to most people, but this train doesn't actually get thrust from the jet engine. The jet engine is used to power an electric generator, which in turn powers electric motors for the wheels. This is how diesel locomotives work too.
I'd guess the reason they say this locomotive is faster is due to the much lower power to weight ratio of the jet turbine compared to diesel engines. I don't see how this would make any difference on a fully loaded train, however, as the delta in weight between a jet turbine and a diesel engine has to be a small fraction of a percent of the overall weight of the train.
When hydrocarbons are burned throroughly, the only waste products are hydrogen and carbon. These can be safely absorbed into the ecosystem.
Incomplete combustion results in particulate matter and cancer-causing inorganic compounds.
Having been a gas turbine mechanic in the US Navy (gas turbines are used to power the Aegis-class cruisers, Arleigh Burke-class destroyers, and Perry-class frigates), I can say that there are silencers that can be used in the exhaust which will keep the noise down quite a bit... jet airplances are "extra noisy" because the hot gas flows out the back pretty much unabated (small loss to continue turning the gas generator portion, but most energy is "lost" out the back in pure thrust), whereas in a turbine "prime mover" application, much of the exhaust energy is used up turning the power turbine / reduction gear / generator.
Plus the size of the turbines in these locomotives is probably similar to those in Huey/Blackhawk- sized helicopter... you can get a lot more HP out of a physically smaller gas turbine than you can from a diesel (the Navy gets 2500kW from a single Huey-sized turbine/ generator setup). And, to me anyway, the lower frequencies from a diesel are more "penetrating" than the higher turbine freqs...
Another turbine advantage is they can run on almost anything flammable, given the right nozzles etc. Some power plants actually burn pulverized coal in their turbines. They can also run on methane, LNG, etc... so if/when it becomes unfashionable enough/too expensive/whatever to power the trains with dead dinosaurs, they can switch over to something else... (methanol anyone?)
I've always thought a turbine-powered locomotive made a lot more sense from a size/weight/fuel economy point of view than a diesel engine... guess I shoulda patented the idea when I had it back in the mid-90s!
This isn't the first gas turbine locomotive that Bombardier has built. Back in the 70's and early 80's Via (Canada's Amtrak) had a gas turbine train (called the "Turbo") operating between Montreal and Toronto that was built by Bombardier. It wasn't as reliable as diesel engines and didn't offer any particular advantages. Gas turbine engines are considerably lighter than diesels and perhaps a bit more fuel efficient, but light weight isn't very important for a locomotive. I remember once watching the Turbo getting towed through Belleville ON by a diesel unit because there was a couple of inches of snow over the rails and the Turbo couldn't plough trough it.
Most heavily-used mainline railroads in the US do have continuously-welded rail. It's expensive and tricky to build correctly, so they don't bother with it on more lightly-used lines.
Same applies to concrete ties, bi-directional signaling, centralized traffic control, and all the other technologies that make railroads run faster and more efficiently.
is that they don't throttle well. They like to rev up, to VERY high speeds, and stay there. When attempts were made to use turbines in racing cars it was found that this made them very effective for oval racing, but nearly useless for road racing. They're even more useless for road driving with it's stop and start patterns.
They are, however, when used at constant rate, far more efficient than piston engines. This makes them good for turning generators.
This would make them good for *hybrid* cars, in which there is renewed interest. In fact, the locomotives that are in question here are conceptually the same as a hybrid car.
KFG
The M1 tank has a turbine engine also. Generally these types of engines are used in applications where a high power-to-weight ratio is required and cost is not the issue.
I'm a firm believer in the philosophy of a ruling class. Especially since I rule. -Randal, Clerks
Most modern jet engines are high-bypass turbofans. A great deal of the exaust energy is captured in the turbine section and used to spin the big fan at the front of the engine. The result is that rather than generating thrust by ejecting a relatively small mass of exaust gas out the back at supersonic speeds, they pump a large quantity of air at subsonic speeds. The result is a quieter and more efficient powerplant.
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This doesn't really change your main point though. These aren't going to be as noisy as a jet engine.
I'm going to guess though that these turbines are going to be a lot bigger than the ones in a huey. Or maybe not: http://www.bombardier.com/index.jsp?id=1_0&lang=e
Looks like they are about half again as powerful. I was imagining a freight locomotive.
Sorry, dag - Union Pacific beat you to it by about 4 decades. Back in the 1960s they experimented with 10,000 HP gas turbines that burned Bunker C oil. Eventually, reliability problems and the rising price of price of Bunker C did them in. However, they screamed like banshees and weren't allowed in many parts of the UP system due to their noise problems. While I'm sure advancements in noise damping tech will help significantly, it's hard to keep something producing several megawatts quiet.
I doubt that existing trains will be able to be retrofitted with one of these things - at least, they won't be able to to take full advantage.
If you're trying to build a high-speed train, all the running gear has to be rated for that high speed. That means suspension, brakes, etc. etc, and applies to all the carriages, not just the locomotive.
Just adding one of these to a train would be like bolting a Formula One race engine in a Civic - it could probably be done, but it wouldn't be safe to use anywhere near its full potential.
Not to mention that train tracks have maximum rated speeds also, so if you upgrade to high-speed trains you have to upgrade to appropriate track standards. Such upgrades are potentially quite expensive (you have to widen bends to reduce lateral G's, for instance).
Any sufficiently advanced technology is indistinguishable from a rigged demo
--Andy Finkel (J. Klass?)
That's just another way of saying "let the bondholders pay for the mess." Which isn't necessarily a bad idea, but someone ultimately is going to have to pay.
Let a new company with new vision and an eye towards the future of transportation develop a high tech train system in America.
There's not a single passenger train system in the world that isn't subsidised by some government. Cut the funding and you can expect ticket prices to rise and the number of passengers to drop sharply.
Of course in todays low interest rate environment maybe the system could be sustained, at least until interest rates start going up again.
We don't need old companies to make a new train system.
Considering that it's only old companies that have the capital to make a new train system, yes we do.
A tubine in this application would funnel its exhaust gas through a series of chambers that increase in size to transfer the energy in the the hot pressured air into work for both compressing intake air, and turning the shaft connected to the generator. It wouldn't power the train with high speed exhaust. Its actually pretty similar to a big turbocharger in an automobile. After it is exhausted, a muffler would rob some energy, through backpressure, but the turbine would get most of it. I don't know how loud these would be, Triumph, or another European auto company used turbines in one of their cars for a few years.
Degaussing scares the bad magnetism out of the monitor and fills it with good karma.
I think if we were to design a gas-turbine locomotive in 2002, the worries about fuel consumption, noise levels and exhaust emissions are no longer major issues, thanks to the efforts of GE, Pratt & Whitney and Rolls-Royce in the last 25 years in dramatically reducing fuel consumption, noise levels and harmful exhaust emissions on airliner jet engines. A Turbo Train using a modified version of today's modern jet engines would be quite powerful, generate much less noise, have very low emissions and would be far more efficient than the old GE Big Blows that UP used during the 1950's and 1960's.
However, we still must eliminate a big problem with gas turbines: the hot exhaust from the engine. Both GE Transportation Systems and GM's EMD will have to figure out how to cool that exhaust in a very small space before we can build a modern gas-turbine locomotive. Remember, we're not taking about a ship, where there is plenty of space to either divert the hot exhaust or install various technologies in the exhaust stream to cool the hot exhaust.
Thus US rail passenger vehicles must be built to withstand impact with freight trains. Other nations have a far greater percentage of passenger-only track including many dedicated lines. Also in many nations the rail infrastructure has been continuously modernized resulting in more sophisticated switching and control system.
Amtrak inherited its system after decades of private neglect and was originally a way to prevent the various passenger rail services in the US from individually being shut down or sliding into bankruptcy. That passenger rail still survives in the US at all after decades of far less support then virtually every other transportation medium speaks to its tenacity and durability. Unfortunately Amtrak has always been stuck with conflicting missions and starved for infrastructure (again, much of what it began with was already obsolete or decrepit; upgrades, replacements and refurbishments have always been piecemeal and/or minimal.) That and impressively bad management.
Another problem has been the extraordinarily high strength requirement has been set by the US's Federal Railroad Administration which results in US rail passenger cars being at a minimum of twice as heavy as every other nation's. A result is that there is literally no other market for US vehicles thus tried & proven designs from other nations can't be used in the USA. Spanish, Swedish, German, etc. - none of their highly successful trains can now be imported into the US due to the FRA's unique requirements.
Thus when folks point out the curiosity of Amtrak hiring the consortium of Alstom/Bombardier to design & build the Acela instead of buying a successful somethingelse model they're ignoring that the somethingelses simply aren't allowed to run in the US on an ongoing basis. After license and redesign fees it would have cost more to convert an existing train then to just design & build one to Amtrak's (& the FRA's) unique requirements, which is what was done.
Of course now Amtrak & Alstom/Bombardier are mired in suits and counter-suits, ignoring the mediation structures built into their contracts and publicly blaming each other for the problems the Acela is facing. Amtrak claims the Acela doesn't meet specifications and was delivered late. Alstom/Bombardier claim Amtrak wasn't timely in providing specifications and making design decisions, many of the problems are with features Alstom/Bombardier advised against, and that Amtrak is running the vehicles on substandard track & caternary against Alstom/Bombardier's recommendations.
Of course much of this could have been avoided had the usual process of building a test train, running it ragged for a year, then dissembling it to examine it for understanding of it's rail performance, maintenance characteristics, wear patterns, practical experiance, then refining the design before going into production been followed. Indeed reexamination of the original train's evaluation appears to show the precursors of many of the problems now appearing on the Acela.
Instead however Amtrak ordered 20 trains in one design/build package (and now claims it'll never order another.) Thus as each trainset was built it was manufactured slightly differently from the ones before as experience was applied and improvements made. This now gives Amtrak 20 subtly different trainsets and no further application of the lessons learned nor incentive on the designer/manufacturer to refine the vehicle.
Whatever the case the losers are the citizens of the US & Canada. Why Canada? It turns out the money Amtrak used to purchase Acela Express was from a $1 billion low-interest loan from the Export Development Corp. of Canada. Yep, if Amtrak goes belly-up not only will the US public be out but also the Canadians. As you can imagine the prospect of a US quasi-governmental agency going belly-up and forfeiting on it's debts to Canada doesn't play well north of the border
Ironically there is a widely rumored proposal in Canada for investing CA$3-billion to improve train service in the Quebec City to Windsor corridor (incl. Montreal, Ottawa, Toronto, and possibly Kingston). The "VIAFast" upgrade is expected to take advantage of trains like Bombardier's newly (re)announced turbo train as well as track-swapping with CPR & CNR to create a dedicated passenger rail route. Indeed there's even renewed interest in a new high-speed Calgary-Edmonton corridor route to serve that rapidly growing part of the country.
Anyway, now you know why the US is stuck with slow trains: Inheritance, lack of investment, political game playing, lousy management, and extreme requirements. On the other hand neighbors in much the same situation are instead expanding their rail systems in logical yet ambitious ways. Makes me think of the tortiose & the hare...
I don't read ACs: If a post isn't worth so much as a nom de plume to its author then I wont bother either.
So I take it you designed this train, then? Because the manufacturer says existing rail networks can be used, and I'm more inclined to believe the manufacturer than I am an anonymous coward...
Don't compare old-tech, experimental turbines with what's available now. The whole reason for this project is that turbines are *more* efficient than diesels, not less. If diesels were more efficient, they'd be the first choice for electric powerplants, and they're not- turbines are.
Another reason for this project is that the service requirements of a passenger train are different from that of a freight train. Passenger trains pull lighter loads, travel faster, and need to accelerate more rapidly. Most locomotive technology in the US was designed with pulling freight in mind. Even the passenger locomotives are based on freigh-pulling designs. This project is a clean-slate design, with a specific purpose in mind. It should fulfill that purpose much more efficiently.
High-speed is made possible by the tracks, not the trains. The french TGV (the fastest - 515 km/h that's 320 miles per hour) is a souped-up ordinary train. No exotic technology, no fancy tilt mechanism, no esoteric power system. Just bigger transformers, faster traction motors, faster gearing and more powerful brakes.
But the track. Oooh, the track, it's a smoooooth gentle nicely laid ribbon of steel, designed to be travelled at speeds up to 250 miles per hour.
I plugged "JetTrain bombardier" into google and got postings on the railroad.net forums. Seems quite a few folks there are pretty skeptical. A good read, in all:
I D=5208
http://www.railroad.net/forums/messages.asp?Topic
just my blog and pix
Turbine B: Turbine > Gears > Wheels
Is Turbine B possible?
Not really. The great thing about turbines is that you can run them really hot. The bad thing is they are fragile to shocks. You run these things either at the limit of your metals or use something inherently fragile like ceramics(experimentally at least). This allows you to get a big temperature difference, which means lots of energy can be extracted (at least that's what all those thermodynaics equations seemed to be about.)
If you tried to run it direct to the wheels you'd probably have to run it so cool that any energy efficiencies would be lost. You also wouldn't get the acceleration you can get by putting electric motors under every car in the train, powered by single lightweight generator car.
There are some pictures of this locomotive here
---
"I can't complain, but sometimes still do..." Joe Walsh
With an electric wire on top, adding to the cost. The point of this train is, presumably, that you don't need to electrify the system. It'll still be expensive to upgrade the rails and reroute the track in parts, but not as expensive as the TGV.
Any sufficiently advanced technology is indistinguishable from a rigged demo
--Andy Finkel (J. Klass?)
Sigh,
Time for gas turbines 101. Here's the biggest difference betwen Gas turbines and Diesels. A diesel can idle on almost no fuel whatsoever, that's why you hear them idling all the time. The fuel/wear and tear it takes to start them vastly outweighs the fuel needed to run them for an hour or eight. Because they use a reciprocating compressor, and a reciprocating compressor maintains is efficiency accross its speed and horsepower band (actually dropping off at the top end) you can turn them down to zero HP out and the fuel going in drops to 1-5% of max power.
GT's have a compressor which relies on the velocities of the compressor blades and the air mass flowing through the compressor to make its magic happen. You dump all the vibrating, clanking, and flailing parts of a recip engine and rely on the momentum/dynamics of the working fluid to get a gizmo which takes 14.4 PSI air at the front and shoves 200-300 psi air out the back with one moving part which is in perfect rotary balance.
The problem is: It only performs this miracle in a small RPM range. Slow down by 10% and the efficiency goes to pot. Long story short, GTEs have only one fuel flow setting, ON. that's why the military was working on an APU for the M1 Abrahms tank. IT would keep the housekeeping electrical systes running without throwing all the fuel away!
There have been advancements in GTEs. Variable inlet stators allow them to have a somewhat broader band of acceptable efficiency. I would not be surprised to see that this engine has intercoolers between the compressors stages. This is a BIG help to efficiency (less HP needed to crank the compressor). This is not done in AC engines because intercoolers are bulky, but not heavy. The second thing you COULD do in a train is to use a recuperator. The takes the nice cool compressed air, and heats it with the exhaust air. Saves on fuel big time, reduces the noise and and the thermal plume of the engine. Again bulky but not heavy.
Modern, digitally controlled, intercooled, rucuperated, gas turbine engines are bone head simple to operate and basically have squat for moving parts and maintenance needs. And they're light. Damn light. Mostly air in fact.
Modern Turbochanred intercooled diesels are damn efficient too. Comfortably close to Carnot efficiency. BUT the massize engine block needed to take the reciprocating pistons is god auful heavy. Damn near a solid block of iron.
Modern diesel freight engines need to be heavy because they need lots of traction to get moving. A passenger train hauls mostly air and aluminum. People weigh squat next to 100 ton freights. That's why passenger cars are so long. They're full of air. Its posible for this type of passenger train to weigh 1/20-1/100 of a freight train with the same HP. A lightweight engine will impose much smaller dynamic loads on the track system.
A big limiting factor is the engine weight. Modern high speed/non electric passenger trains have big fat engines up front. In europe, they offload the engine by using overhead electric power.
This is an interesting solution to the speed problem. I hope it works.
> The french TGV (the fastest - 515 km/h that's 320 miles per hour)
> is a souped-up ordinary train.
Pretty "ordinary" yes... but there's one striking feature that differs from ordinary trains:
On a normal carriage, you have two boogie wheel pairs, one on each end of the carriage. On the TGV two carriages shares the same boogie in the intersection. Picture here: TGV boogie
This picture is actually from a tilting prototype of the TGV.
You can read more about the modifications to the TGV (Train Grande Vitesse) here, and some history here.
//TheToon