Wind Resistance

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Posted by BaltACD on Sunday, July 09, 2017 6:25 PM

rossi
https://www.youtube.com/watch?v=OPNmJ23WhsI

It is stupid as quoted. Missed a container right after Arrowedge. It does NOT help in any Wind Resistance Reduction, but add another more frontal impact resistance and trail-side Vacuum/Wake resistances.. 

For a number of years I towed my race car behind a 1984 Dodge Daytona Turbo with a small enclosed trailer - mostly in the Mid-Atlantic, Florida and in between.

I could feel and use the 'draft' from big rigs from 80-100 feet behind.  Fuel mileage on the Daytona would increase about 3 MPH when I was patient enough to follow the trucks for a period of time.

Just because there is an open box space behind the Aeroedge doesn't mean that all it's benefits are lost.

         

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Posted by rossi on Sunday, July 09, 2017 6:52 PM

I have read a Taiwanense professor's PhD thesis at Uof Illinois and AAR (funded by BNSF and CN), stating that the combined aerodyanimc drag increases linearly proportional to Container Gap Size, from 1 foot and saturates at ~12 feet. After 12 feets, the Drag starts all over again like a FIRST Frontal Drag. I also read somewhere(youtube or somewhere?) that Mike Iden of Union Pacifioc complains that the 3/5 articulated container wagons have a Gap of ~11 feet. I do not know the sizes of Independent Car/Wagon. I think they are ~20 to 25 feet length.. I think the aerodynamic drag are pretty much independent each other. Not sure much paltooning works here... 

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Posted by mudchicken on Sunday, July 09, 2017 7:22 PM

samfp1943
 
cx500

For aerodynamics, it isn't just the train speed.  It may only be doing 40mph but if facing a 30mph headwind across the plains the effective wind force is 70mph.  But am among the skeptics as far as the arrowwedge is concerned.

As another thought some containers (perhaps older ones?) have corrugated sides instead of smooth.  They probably add a tiny bit of turbulence and wind resistance to the train.  Of course, like the wedge, the difference is most likely almost immeasurable.

John

 

 

 

 

 

      It seemed sort of unusual to see locomotive mounted Anemometers, at the time. Huh?

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Posted by SD70M-2Dude on Sunday, July 09, 2017 8:56 PM

Buslist
BaltACD
jeffhergert
Met one last night and it seemed like the next platform behind the wedge was a single container, then a few double stacks.  Behind them were a short mix of double and singles, then the remainder of the train were doubles.

The other day it was windy and I had an empty coal hopper train.  Speed would pick up about 5 mph when going through towns or other areas where trees and vegetation would block the wind.  Once back out in the open going by farm fields, speed would drop off about 5 mph.  Not unusual during periods when the winds are blowing hard.

Jeff

Can understand wind resistance with empty hoppers - any noticable wind resistance with a loaded coal train?

There was some work in the late 80s with air foils on the ends and cross braces of hopper cars after it was noticed that it took more fuel to get the empty train back to the PRB than to get the loaded one out of there. Much of the work was done by BN, some in a wind tunnel in Georgia (Lockhead?) under the direction of Steve Ditmeyer. He then turned his attention to Aries and Rockwell.

Has anyone ever tried anything similar with centrebeam or bulkhead flatcars?  CN runs a daily train composed entirely of empty centrebeams from Chicago to Prince George, BC, and it behaves in a similar fashion.  Won't ever hit track speed, even going downhill in throttle 8.  The harder you pull, the harder that train pulls back.

Crews call those cars "sailboats". 

Greetings from Alberta

-an Articulate Malcontent

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Posted by rossi on Wednesday, July 26, 2017 6:07 PM

rossi

I have read a Taiwanense professor's PhD thesis at Uof Illinois and AAR (funded by BNSF and CN), stating that the combined aerodyanimc drag increases linearly proportional to Container Gap Size, from 1 foot and saturates at ~12 feet. After 12 feets, the Drag starts all over again like a FIRST Frontal Drag. I also read somewhere(youtube or somewhere?) that Mike Iden of Union Pacifioc complains that the 3/5 articulated container wagons have a Gap of ~11 feet. I do not know the sizes of Independent Car/Wagon. I think they are ~20 to 25 feet length.. I think the aerodynamic drag are pretty much independent each other. Not sure much paltooning works here... 

 

 
I am not quite sure about the platooning of "multiple trucks" and "intermodal rail containers". The research at UI and AAR said platooning is limited(as said from 1 foot to 12 feet). However, it seems platooning seems works well for multiple trucks(even for BIG gap/distance.)..
 
Can someone explain such discrepancy..
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Posted by Gramp on Thursday, July 27, 2017 7:28 AM

re:Platooning

A truck driver friend said, "We used to call it drafting, the cops called it following toooo close, and now that there's  a computer involved, it's safe and legal.  It might be good, but as usual, it's probably not for me." Smile

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Posted by Cotton Belt MP104 on Thursday, July 27, 2017 10:24 AM
gramp: if you talk to serious bike riders, they platoon when in groups....and due to the "load" the lead biker has, that position is swapped out with "more rested bikers who enjoyed the draft" too i read that flights of fowl will do the same and the leader will swap out for the same reason endmrw0727171024
The ONE the ONLY/ Paragould, Arkansas/ Est. 1883 / formerly called The Crossing/ a portmanteau/ JW Paramore (Cotton Belt RR) Jay Gould (MoPac)/crossed at our town/ None other, NOWHERE in the world
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Posted by rossi on Friday, February 09, 2018 8:51 PM

I saw UP put some extension fairing at the trail-side of Arrowedge+  some Arrowege has put Airtab at trail. I think Airtab is a stupid idea. The extension fairing probably has a some limited saving(+if diluted with 100's of cars). Please comment.   https://www.youtube .com/watch?v=hMsAdOTl2Mg                https://www.youtube.com/watch?v=4GoHzNKrDy0                http://capstone.byu.edu/previous-projects/arrowedge-rear-fairing-extension

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Posted by BaltACD on Friday, February 09, 2018 10:39 PM

rossi
I saw UP put some extension fairing at the trail-side of Arrowedge+  some Arrowege has put Airtab at trail. I think Airtab is a stupid idea. The extension fairing probably has a some limited saving(+if diluted with 100's of cars). Please comment.   https://www.youtube.com/watch?v=hMsAdOTl2Mg                https://www.youtube.com/watch?v=4GoHzNKrDy0                http://capstone.byu.edu/previous-projects/arrowedge-rear-fairing-extension 

While I tend to agree that UP's wedge has limited if any benefit; the reality is that if UP can demonstrate the fuel savings are 1/10th of a per cent - with the amount of fuel that UP uses that adds up to real money for them.

         

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Posted by PennsyBoomer on Saturday, February 10, 2018 12:40 AM

Dakguy201
I am wondering that since the railroad finds the efficiency of the Arrowedge sufficient to surrender a revenue producing place on the train, would it also make sense to ship an empty container on any car that would otherwise be a single stack?

Well just don't put an empty container on top, as they've been known to blow off on Sherman Hill, where the wind rages.

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Posted by Overmod on Saturday, February 10, 2018 4:11 PM

The reality is that UP won't observe even a fraction of that reduction in fuel burn, as it only applies to reasonably frontal resistance on the relatively few train-miles run with them.  I have not seen actual dynamometric reference to the change in resistance of version 2 over version 1, but I'm of the opinion neither one does much practically.

But you are using the wrong criterion even for fuel burn by omitting the fuel consumed in picking and placing these devices on consists (no GHA being available even with expedient prayer to do that for you) or the additional non revenue tare weight that must now be hauled up any grades.  Or the costs involved in fabricating the things (this being a major point in going to version 2) and keeping them around in active yards in sufficient numbers and in expedient places to put on consists.

When you actually cost this out, I doubt it makes any more sense than UP steam streamlining did -- the money is in the marketing appeal and the perception of the unwary. Pity, because I liked the look of version 1's RV-like shape (and I don't mean recreational vehicle, at least not in the Bago sense...)

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Posted by samfp1943 on Saturday, February 10, 2018 9:20 PM

Anj intersting topic for a Thread!  After reading it back to the original poster's Thread.  And not being an academic but just a casual observer. 

The main issue in my mind, boils down to a #1 area of interest, ultimately, that of dwell time for the train? The gathering of equipment and then the assembly of the train; followed by the actual loading, confirmation of various administrative functions for that train. Lastly, ultimate departure to the next point in the life of that train.   Basicly TIME !  Everything else is part of the academic excercise to extract as much revenue as possible from the specific train.

The aerodynamics, fuel consumption x number of units needed to move the train over the railroad. As with long evolved railroad practices; trains may be 'solid' to the final destination, or they may be 'blocked' to facilitate delivery as blocked to those points needed by the railroad.  Each adderd enhancement may add to the amount of dwell time at the TERMINAL.  Balance that with whatever fuel savings can be developed within the parameters of a specific railroad operation. And at some point fit in the practical benefits of aerodynamics and that amount of savings. Each step in the process becomes a balance of trade-offs. IMO.

I am sure others here are more competent to discuss the dollar amounts, and the academic of those points.   Before this subject can be adapted in the practrical, real world  of today's railroading. My guess is the 'systems' will have to be re-engineered from the very concept to its realistic applications.

Remember, the Thread and its poltos, some time back whe one of UPRR's "Arrowedge" devices met its' demise on a low highway bridge in Wisconsin? Apparently, left on a train as it was reworked and sent out on an un-tested routing?  THAST was probably, pretty expensive, and problematic for UPR?

THe gaps between well cars is not uniform and seems to vary with each reloading(?) 20' TEU's (in pairs) 40' cans (stacked) 45' cans (stacked on top of shorter cans.) 53' cans stacked on whatever else is available to be stacked on?).

Chemical tanks, generally, singled out in the wells (without stacking them/Haz-Mat regs?) 

TOFC Trains with their trailers ( aerodynamic enhacements are loaded according to the 5th wheels availibility/ trailer may be loaded backwards facing, in which case, they are not helpful to the over all areodynamics within the train). 

The original posting of the PDF and its research is just that, another academic exercise with interesting results. Practical? Who knows at this stage of the game. It seems to come down to the availability of 'seed money' from Uncle Sam.                  Or local politicians legislating 'feel good' laws; to garner votes from their cnstituants. Enhancements, that ultimately, wind up costing the consumer in the cost to get goods to the points of sale? Whistling

 Cynical, you bet I am!  The following link shows some insight:Linked @ https://www.thebalance.com/what-is-the-value-of-a-dollar-today-3306105

 

 

 

 

 

Sam

 

 


 

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Posted by Overmod on Saturday, February 10, 2018 10:11 PM

Part of the problem, I think, is that neither the original Arrowedge or its college reboot really seem to have a grasp of the aerodynamics around loaded stacks.  The reason for the 'crash' was that the device experienced aerodynamic lift but was not twistlocked down; that was not too bad in itself until you started looking back along the top of the train at the effect of 'enough' disturbed air to raise the back of the wedge with that much force.

One major mode of resistance (which I originally saw modeled for TOFC consists on those delightful ATSF Fuel Foilers) is the train making speed into a quartering wind, so that the resultant of slipstream and wind is incident on all the 'fronts' in the train and there is minimal effect from 'vacuum' or drafting pressure reduction from the trailer(s) ahead.  The 'correct' answer here is to provide the equivalent of full-width diaphragms between trailer bodies or containers; you still have the lateral-pressure and drag increase on the surface, but not all those square feet encountering overpressure.

It's comparatively simple to arrange a modification of modular dunnage that has frames that twistlock to the 'front' and 'back' of a container with an internally -reinforced inflatable cell given a tough outside surface.  'Theoretically' these could be easily deployed as the train is loaded, in near-parallel with crane lifts so any critical-path extension is relatively minimal, and the deflated device easily rides on one container or the other during unloading and can even, in a pinch, be roaded.

You don't see these marketed, which should tell you a bit about relative economics: fuel surcharges are a whole lot easier, and about as bottom-line effective, as streamlining savings.  And when 'real' streamlining involves far more than flow-smoothing the front of the train consist over the power, it's relatively easy to see why not much has been tried up to now.

Something that hasn't been mentioned here is the extreme low tare weight of modern well-car equipment.  That has proven a source of considerable saving in intermodal operation.

 

 

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Posted by CMStPnP on Saturday, February 10, 2018 10:36 PM

Overmod
I doubt it makes any more sense than UP steam streamlining did

Wasn't part of the purpose of the steam streamlining to channel the coal smoke from the stack?    Didn't it work in that respect?

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Posted by Overmod on Saturday, February 10, 2018 10:52 PM

CMStPnP
Wasn't part of the purpose of the steam streamlining to channel the coal smoke from the stack?    Didn't it work in that respect?

According to Kratville, not very well.  In my relatively extensive research into 'smoke lifting devices' I never found any skyline-casing device that actually worked as intended, and some (like the headlight on the superb NZR K-class 4-8-4s) that caused more problem than they solved.

In any case, if you think about it a moment all these devices were meant to deflect air powerfully in a direction it didn't want to go.  That will tell you they induced more drag than proper streamlining would, meaning they would be dissipating more horsepower -- increasingly more horsepower as the engine started to produce relatively less and less -- at speed.

I am not saying that all streamlining was purely 'tin' for marketing purposes; certainly the engines under the streamlining were two of UP's best up to that point, and were regularly run well into the speed range where practical streamlining begins to show value.  But I don't think either shroud was particularly more aerodynamic than Kantola's for 5344, which I think 'peaked' at saving about 300hp.  That's not going to translate into much overall fuel savings, and full shrouding could be incredibly heavy (remember that 3765 was to have gotten a Mae West shroud, but even the skirting would have made her too heavy and was never applied).  So I think most of the parallels between the Arrowedge effort and the two 'Steamliners' can be drawn effectively.

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Posted by jeffhergert on Monday, February 12, 2018 3:12 AM

Since UP bought Railex and the order of the day is G-55, many intermodal trains now have blocks of reefers (sometimes more reefers than stacks) and/or autoracks.  I saw an intermodal with a block of reefers behind the power and in front of the first stack car.  That first stack car had an arrowedge on it.

I have no doubt that during severe wind conditions an empty coal train burns as much, or more fuel as a load.  I've had empties where the speed picks up by about 5mph when you go through places with wind breaks, such as towns.  Back out in the relative open farm land, speed drops back off by about 5mph.  Stack and autorack trains are slowed by high winds too.  I doubt the arrowedge does much good in a crosswind.  Heck, I doubt it does any good at all.

Jeff

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Posted by rossi on Monday, February 12, 2018 10:41 AM

http://capstone.byu.edu/previous-projects/arrowedge-rear-fairing-extension

http://capstone.byu.edu/previous-projects/arrowedge-intermodal-fairing

Union Pacific develped this Arrowedge ~10 years, claiming that taking care of the frontal impact wind resisatnce at the first car will be enough at first car. The aerodynamic drag of Hundreds of Gaps between cars is not big enough to worry about(possibly platoooning). However, this Arrowedge Extension Fairing said that closing the gap after Arrowedge is important and good. Can someone tell why a gap right after Arrowedge is important, but the Hundreds of Gap afterward is not important.. Also there are 2 types of Gap, one is ~3.5 meter(articulate car), another is ~7 meter(independent car). So question is, is inter-car gap an important aerodynamic drag or not? If no much drag, ok, close of story. If yes, what is the Quantitative relationship between gap sizes(3.5 and 7 meter) and aerodyanamic drag?  We saw UP and BYU can not tell this ultimate point Clearly, for ~10 years..

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Posted by Overmod on Monday, February 12, 2018 11:37 AM

Well, as Leonardo da Vinci said at 18, when you find out the 'authorities' on a particular issue (in his case Aristotle on what we now call gravitational acceleration) are demonstrably not just in error but flat wrong, you have to take the course of learning about the subject 'from all angles' yourself until satisfied you understand the actual 'thing as it is'.  Welcome to one of the right parts of the Western tradition.

What I cautiously advise you NOT to do is start cussing UP and the kids in Utah as 'liars' just because they haven't quite done their homework.  Science works a funny way - find a better physical model of what either Arrowedge does or doesn't do; go into Research Reports in the e-library and see what you find; model the interaction of a train with quartering wind at different speed or angle; look at a recent thread describing centerbeams to see why cars with lots of lightening holes are harder to pull than those without -- and all of them much harder to pull than several good engineers here say they would have expected until they found out for themselves.

It's also possible for designers to think, with a clear conscience, that their bold new theory of aerodynamic drag reduction for railroad trains is correct.  Here again I am reminded of Angus Sinclair commenting on the little arrows that show steam flow in patent drawings.  Since steam doesn't know how to read, sometimes it flows a decidedly different (and less lucrative to the patent holder) way.  Shakespeare had a character who proudly thundered his knowledge: "I can call spirits from the vasty deep!" -- but another character who promptly stuck a pin in it by asking quietly "but do they answer?"  The criterion here is absolute drag reduction, measured at the power drawbar, under the weighted average of all the conditions encountered over actual trips.  Plus the cost of building, maintaining, handling and perhaps being inconvenienced by any special equipment.

Very knowledgeable and skilled people have been studying and experimenting with more efficient 'front ends' for steam locomotives.  A problem is that the 'default' design is not necessarily the most thermodynamically effective; the actual equipment should be capable of 'automatic action' without needing adjustments or wacky moving parts; it shouldn't produce 'crazy high' superheat in some of the elements at high speed; it should deal effectively with 'sparks' and soot in the combustion gas, etc.  When even spectacular math produces results that don't do those things, both the design and the design principle run the risk of being exposed as failures at best, and snake oil far from the worst.

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