Question on Steam Engine Power

switchdoc

New member
Hi Folks,

recently I downloaded some steam engines and testrun them on my 'lab-layout'. It turned out, they were much too powerful compared to the real life ones. Here is an extract of one engine spec:

firebox-volume 1600
firebox-to-boiler-heat-flow 0.055
firebox-efficiency 0.9
boiler-volume 13800
maximum-volume 9600
minimum-volume 5600
water-injector-rate 5.7
westinghouse-volume 80
main-reservoir-volume 50
piston-volume-min 10
piston-volume-max 228.207
piston-area 0.3117
piston-angular-offsets 0.0174,1.5254,3.0333,4.5413
boiler-to-piston-flow 0.0045
piston-to-atmosphere-flow 0.003
safety-valve-low-pressure 1720
safety-valve-low-flow 0.0005
safety-valve-high-pressure 1730
safety-valve-high-flow 0.01
max-fire-coal-mass 80
max-fire-temperature 1450
shovel-coal-mass 1.5
burn-rate 0.001
fuel-energy 25000
initial-boiler-temperature 450
firebox-to-boiler-heat-flow-idle 0.003
burn-rate-idle 0.003

It went uphill a 2 percent grade (20%o) with a consist of 900 tons at 38 kph, whereas the datasheet of the real one only gives 270 tons for that grade an speed. (Not really the BigBoy, isn't it ?)

So I would like to tweak it to more lifelike data. All the data above are detailed in CCG, some however withou any useful unit.

Does anybody have some knowledge which physical units are applied, especially for

firebox-to-boiler-heat-flow - unit ? Megawatts ?
piston-to-atmospheric-flow - dia or area ?
safetyvalve-low-flow - same (not that important)
savetyvalve-high-flow - same (not that important)
burn rate - unit ? kilograms per second ?
boiler-to-piston-flow - unit ?

BTW: What is the Westinghouse volume ??

Would be happy to get some idea.

Norbert
 
Hi Folks,

...

Does anybody have some knowledge which physical units are applied, especially for

firebox-to-boiler-heat-flow - unit ? Megawatts ?
piston-to-atmospheric-flow - dia or area ?
safetyvalve-low-flow - same (not that important)
savetyvalve-high-flow - same (not that important)
burn rate - unit ? kilograms per second ?
boiler-to-piston-flow - unit ?

BTW: What is the Westinghouse volume ??

Would be happy to get some idea.

Norbert
Welcome to the club, Norbert. If you test accurately you find most don't fair too well.

1st the easy one: Westinghouse volume isn't used at all - any number will suffice. I always thought it had something to do with the air brakes - the air pumps are stream driven and would represent a load on the bolier but just a thought.

For flow they talk about nominal hole size which might be diameter or area. I don't think anyone has correlated it to some physical characteristic of the locomotive steam piping or valves. Auran has been completely silient on any of the spec content right from the start 4 yrs ago.

Burn rate - this one I know from testing is kgs/sec. However it only applies to the rate at which coal is consumed until the fire temp reaches the max temp specified in the config. Once that temp is reached the burn rate changes to some hard coded value and the fire temp spikes up and down but always above the max temp value until the coal is consumed (the fire temp then drops to some idle temp abt 18% of the max) or another shovel of coal is added with the cycle starting over.

The heat flow has to be an energy flow of some sort but seems to be with respect to some other characteristic of the furnace as it doesn't vary a lot from loco to loco so one might expect it to be related to some other input in the spec (like firebox volume except it has no effect at all on loco performace). Normally I just set it to a typical value and then after all the other params are set adjust it so the boiler evaporation will just sustain the steam consumption while operating at a speed and cutoff setting that produces a specified max hp output.

Bob Pearson

PS I might add to elaborate on what Pencil said, I never use actual piston areas or cylinder volumes in the specs I set up. I think there are some flaws in Auran's steam setup and always input "adjusted" values for these that will produce starting TE and water consumption consistent with prototype values.
 
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Thanks both of you. I guess I will have a lot of reading to do with the thread Pencil indicated. And I will put in my two pennies worth into that thread - if i come up on something. No sense in having too many threads covering the same (important) thing.

Norbert
 
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