Re: Japan upgrades to 320 km/h
Damon Hill
news:slrnhiukml.4js...@Odysseus.Zierke.com:
>
> http://www.youtube.com/watch?v=-EnBClBNw0Y
>
>
What's the function of the 'fins' adjacent to the pantographs?
I'm wondering if the wind buffet at these speeds affects the
contact with the catenary wire...
--Damon
Stephen Sprunk
The latest record run by the TGV was nearly twice as fast and had no
contact problems despite not having similar fins, so I doubt it. At the
tension necessary for high-speed operation, I can't imagine wind has any
effect at all.
I'm surprised they run with both pans up, though; early on, the TGV
folks had problems with traveling waves in the catenary which required
putting one pan down and running a high-voltage wire from one power car
to the other.
S
--
Stephen Sprunk "God does not play dice." --Albert Einstein
CCIE #3723 "God is an inveterate gambler, and He throws the
K5SSS dice at every possible opportunity." --Stephen Hawking
James Robinson
>
> I'm surprised they run with both pans up, though; early on, the TGV
> folks had problems with traveling waves in the catenary which required
> putting one pan down and running a high-voltage wire from one power car
> to the other.
Running with two pantographs is pretty well the norm:
http://www.youtube.com/watch?v=nwozr6QdrE0&feature=PlayList&p=0F33E560A90A7054&index=6
http://www.youtube.com/watch?v=MTLKus6fHI8&feature=PlayList&p=0F33E560A90A7054&index=8
James Robinson
>
> I'm surprised they run with both pans up, though; early on, the TGV
> folks had problems with traveling waves in the catenary which required
> putting one pan down and running a high-voltage wire from one power car
> to the other.
Running with two pantographs is pretty well the norm:
http://www.youtube.com/watch?v=nwozr6QdrE0
http://www.youtube.com/watch?v=MTLKus6fHI8
Larry Sheldon
> Damon Hill wrote:
>> Hans-Joachim Zierke<Usenet...@Zierke.com> wrote in
>> news:slrnhiukml.4js...@Odysseus.Zierke.com:
>>> http://www.youtube.com/watch?v=-EnBClBNw0Y
>>
>> What's the function of the 'fins' adjacent to the pantographs?
>
>> I'm wondering if the wind buffet at these speeds affects the
>> contact with the catenary wire...
>
> The latest record run by the TGV was nearly twice as fast and had no
> contact problems despite not having similar fins, so I doubt it. At the
> tension necessary for high-speed operation, I can't imagine wind has any
> effect at all.
>
> I'm surprised they run with both pans up, though; early on, the TGV
> folks had problems with traveling waves in the catenary which required
> putting one pan down and running a high-voltage wire from one power car
> to the other.
Could it be that the fins are to kill the standing wave? Or change its
wavelength?
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Philip Nasadowski
James Robinson <was...@212.com> wrote:
> Running with two pantographs is pretty well the norm:
On 1.5kv systems, yes. On 25kv systems, no. The TGV runs 2 pans up on
1.5kv (and 3kv?), but on AC, is one pan up. I think the older ICE
trains have two pans up, but they are also somewhat slower, and newer
ones only use one pan on AC.
Anyway, the TGV doesn't run at high speed on 1.5kv, and the LGVs are all
25kv, thus they run a single pan at high speeds.
FWIW, some classes of French locomotives I believe required both pans up
at low speeds on DC. 1.5kv is not a very punchy system at all.
Philip Nasadowski
Larry Sheldon <lfsh...@gmail.com> wrote:
> Could it be that the fins are to kill the standing wave? Or change its
> wavelength?
Probably some airflow thing. Note the pan design seems to be a very
minimal/lightweight one. I suspect that they maintain a *very* tight
wire height, thus the travel is minimal. They've played with other
designs over the years, I think mostly for noise reasons.
Interestingly, the Japanese still seem to use a lot of cross arm pans,
even on newer stuff. They're weird like that, go figure.
FWIW, Japan had regular steam operations until 1975...
Damon Hill
@news.eternal-september.org:
> Damon Hill wrote:
>> Hans-Joachim Zierke <Usenet...@Zierke.com> wrote in
>> news:slrnhiukml.4js...@Odysseus.Zierke.com:
>>> http://www.youtube.com/watch?v=-EnBClBNw0Y
>>
>> What's the function of the 'fins' adjacent to the pantographs?
>
>> I'm wondering if the wind buffet at these speeds affects the
>> contact with the catenary wire...
>
> The latest record run by the TGV was nearly twice as fast and had no
> contact problems despite not having similar fins, so I doubt it. At the
> tension necessary for high-speed operation, I can't imagine wind has any
> effect at all.
>
> I'm surprised they run with both pans up, though; early on, the TGV
> folks had problems with traveling waves in the catenary which required
> putting one pan down and running a high-voltage wire from one power car
> to the other.
Take a closer look at the video; only the trailing pan is raised.
--Damon
Stephen Sprunk
> On 12/21/2009 8:22 PM, Stephen Sprunk wrote:
>> Damon Hill wrote:
>>> Hans-Joachim Zierke<Usenet...@Zierke.com> wrote in
>>> news:slrnhiukml.4js...@Odysseus.Zierke.com:
>>>> http://www.youtube.com/watch?v=-EnBClBNw0Y
>>>
>>> What's the function of the 'fins' adjacent to the pantographs?
>>
>>> I'm wondering if the wind buffet at these speeds affects the
>>> contact with the catenary wire...
>>
>> The latest record run by the TGV was nearly twice as fast and had no
>> contact problems despite not having similar fins, so I doubt it. At the
>> tension necessary for high-speed operation, I can't imagine wind has any
>> effect at all.
>>
>> I'm surprised they run with both pans up, though; early on, the TGV
>> folks had problems with traveling waves in the catenary which required
>> putting one pan down and running a high-voltage wire from one power car
>> to the other.
>
> Could it be that the fins are to kill the standing wave? Or change its
> wavelength?
I don't see how fins could do that. From what I've read, the wave speed
and magnitude depend completely on the contact wire tension.
The TGV folks had to make the above modification because the TGV's rear
pan was running into the trailing wave of the front pan--not a problem
at lower speeds because the wave dissipated before the rear pan reached
it. On the record runs, the front pan kept running into _its own_
leading wave, and they had to temporarily increase the contact wire
tension to keep the wave moving faster than the train did.
If there was a way to eliminate the wave entirely, I have to think
SNCF/Alstom would have found it over the last three decades. They seem
to be resigned to having to monkey with the pans and tension, though.
Valentin Brückel
> In article <Xns9CE8DAC14E9...@94.75.244.46>,
> James Robinson <was...@212.com> wrote:
>
>> Running with two pantographs is pretty well the norm:
>
> On 1.5kv systems, yes. On 25kv systems, no. The TGV runs 2 pans up on
> 1.5kv (and 3kv?), but on AC, is one pan up. I think the older ICE
> trains have two pans up, but they are also somewhat slower, and newer
> ones only use one pan on AC.
The older ICE trains are basically two locos with a variable number of cars
in between. There is no high-voltage connection between the powercars.
ICE2 trains are very similar to the ICE1 except for two cab cars in the
middle of the train so both halves can operate independently (and even more
similar to conventional trains). When two halves were coupled power car-to-
cab car, they were speed limited because of the pantograph issue. If coupled
power car-to power car, they still are. [1]
If newer trainsets operate coupled, the pantographs most distant from each
other are raised automatically.
Val
[1]: In ASCII:
___________________
< >
/======\/======\ top speed: 280 km/h
___________________
< < top speed: 280 km/h
/======\/======\ (originally 200 km/h)
___________________
> < top speed: 200 km/h on HSLs
/======\/======\ 160 km/h on conventional lines
(including 200-km/h-lines)
Bernhard Agthe
Damon Hill wrote:
> Take a closer look at the video; only the trailing pan is raised.
Which would be standard procedure if an engine or a train set can be
operated with one - use the rear one. That way if it fails, the debris
will not damage the front one, allowing the train to continue under it's
own power after stopping (hopefully stopping at a section where the
catenary is intact and not damaged by the destroyed panto).
Long ago I did see a video of an engine running at speed with a
(intentionally modified) broken pantograph. The catenary did flip-flops
while the pieces of the disintegrating panto were ejected in all
directions ;-) They said in the video that they actually didn't expect
the catenary to survive that test.
So the train would run idle and hopefully make it to the next section of
wire, raise the other pantograph and continue. With the ICE trains (as
described elsewhere in this thread) both need to be raised, it might be
similar with other train sets, especially on 1.5kV or 3kV DC systems
where power transmission is an issue. I've seen double catenary in
mountain sections on DC lines...
Merry Christmas...
Larry Sheldon
> Take a closer look at the video; only the trailing pan is raised.
I guess I am not familiar enough with the equipment--I couldn't say if
there was a difference, and if there was, what it was.
Larry Sheldon
>> Could it be that the fins are to kill the standing wave? Or change its
>> wavelength?
>
> I don't see how fins could do that. From what I've read, the wave speed
> and magnitude depend completely on the contact wire tension.
I've not seen any facts in the matter--in aviation there are
modifications that are no intuitively obvious ("winglets", tine fins on
the top of the wings, fillets, subtle shape-changes) but which move
shockwaves, control separation, modify wing-tip vortices, all kinds of
stuff.
I've seen movies of wind-tunnel tests and am convinced they work,
although in many cases I don't know why or how.
I can see how the "fin" structure might generate a balancing shock wave,
or channel air-flow to keep it on top instead of spilling over the side.
In any case I don't know, and it appears that nobody that does has
spoken up, so I'll put that in the Mystery box until somebody that does
know speaks up.
> If there was a way to eliminate the wave entirely, I have to think
> SNCF/Alstom would have found it over the last three decades. They seem
> to be resigned to having to monkey with the pans and tension, though.
Took a while for people to understand wing-tip vortices and clear air
turbulence. And that the Sun didn't revolve about the Earth, which is
pretty obvious if you think about it.
You'd think they would have figured out how to run the trains on time by
now, wouldn't you?
James Robinson
> Took a while for people to understand wing-tip vortices and clear air
> turbulence. And that the Sun didn't revolve about the Earth, which is
> pretty obvious if you think about it.
One in five Americans still think the sun revolves around the earth, so it
isn't as obvious as you might think:
http://www.smirkingchimp.com/thread/12245
And those people are still allowed to vote.
Greg Gritton
> Larry Sheldon <lfsh...@gmail.com> wrote:
>>
> One in five Americans still think the sun revolves around the earth,
> so it isn't as obvious as you might think:
>
> http://www.smirkingchimp.com/thread/12245
>
> And those people are still allowed to vote.
I had a friend in high school who was quite smart, knew science well, etc.
Yet, he joined the flat earch society. He joined for fun; he had
no illusion that the earth was flat.
I wouldn't be surprised if 1/5 of the peopulation wouldn't answer
such an easy and obvious question wrongly just for kicks.
Greg Gritton
Larry Sheldon
> Hello James,
>
>> Larry Sheldon <lfsh...@gmail.com> wrote:
I wrote noting of the sort.
>>>
>> One in five Americans still think the sun revolves around the earth,
>> so it isn't as obvious as you might think:
>>
>> http://www.smirking chimp.com/thread/12245
>>
>> And those people are still allowed to vote.
The very same ones that post nonsense like this.
>
>
> I had a friend in high school
I doubt that very much
tobias b koehler
> On 1.5kv systems, yes. On 25kv systems, no. The TGV runs 2 pans up on
> 1.5kv (and 3kv?), but on AC, is one pan up.
Or two if two trains are coupled.
> I think the older ICE
> trains have two pans up, but they are also somewhat slower, and newer
> ones only use one pan on AC.
ICE 1 is "long enough" that they don't influence each other. The later
series are "half trains" that can be coupled together if needed. Such a
"double half train" still has 2 pantographs on the wire.
> FWIW, some classes of French locomotives I believe required both pans up
> at low speeds on DC. 1.5kv is not a very punchy system at all.
Yes, otherwise the wire would heat up too much ....
tobias b koehler
> What's the function of the 'fins' adjacent to the pantographs?
They could just be there to reduce noise? After all a good part of the
noise that a high speed train makes is caused by the wind, and the
pantograph appears to be a significant part of it.
Damon Hill
@news.albasani.net:
Somehow that doesn't seem like an adequate explanation, but I'm at
a complete loss to otherwise explain its function.
--Damon
Stephen Sprunk
> On 12/21/2009 10:29 PM, Stephen Sprunk wrote:
Please do not remove attribution lines.
>> Larry Sheldon wrote:
>>> Could it be that the fins are to kill the standing wave? Or change its
>>> wavelength?
>>
>> I don't see how fins could do that. From what I've read, the wave speed
>> and magnitude depend completely on the contact wire tension.
>
> I've not seen any facts in the matter--in aviation there are
> modifications that are no intuitively obvious ("winglets", tine fins on
> the top of the wings, fillets, subtle shape-changes) but which move
> shockwaves, control separation, modify wing-tip vortices, all kinds of
> stuff.
>
> I've seen movies of wind-tunnel tests and am convinced they work,
> although in many cases I don't know why or how.
It's pretty simple, actually; it's amazing it took the industry so long
to figure them out, in retrospect.
Planes fly because the shape of the wing causes the airflow over the
wing to be at a lower pressure than the airflow below the wing.
Winglets form a wall that prevents air from rotating (i.e. leaking)
around the wing tip from the high pressure area to the low pressure
area, which maximizes the pressure differential. The result is more
lift, which means better fuel economy. The vorticies are moved from the
tips of the wings to the tips of the winglets, but the tips are much
smaller and position relative to the laminar flow over the wing is
different so there is less turbulence, which also means less drag and
also better fuel economy.
> I can see how the "fin" structure might generate a balancing shock wave,
> or channel air-flow to keep it on top instead of spilling over the side.
If that were necessary, I'd expect to see fins along the entire length
of the train. Or are you saying that it's just the (air) shockwave from
the pan itself? I suppose fins might contain a little _noise_, but the
pan's affect on the air won't have any meaningful effect on the contact
wire, and most of the noise comes from the wheel/rail interface.
> In any case I don't know, and it appears that nobody that does has
> spoken up, so I'll put that in the Mystery box until somebody that does
> know speaks up.
Fair enough.
> You'd think they would have figured out how to run the trains on time by
> now, wouldn't you?
We know exactly how to run trains on time; it's just that almost nobody
is willing to do what it takes because of the cost (political, economic,
etc.). The same is true in most other industries: we get what we're
willing to pay for, not what is _possible_.
Miles Bader
>> most of the noise comes from the wheel/rail interface.
>
... and supposedly aerodynamic noise near populated areas is one of the
major factors limiting speed increases on Japan's existing Shinkansen
network.
[Long segments of the new Chuo Shinkansen will be built underground,
which should help a bit!]
-Miles
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"An atheist doesn't have to be someone who thinks he has a proof that
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evidence on the God question is at a similar level to the evidence on
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