Steamturbine engines!

Propulsion systems, machinery, turbines, boilers, propellers, fuel consumption, etc.
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Nellie
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Steamturbine engines!

Postby Nellie » Tue Sep 20, 2005 10:38 am

Do anyone know how exactly they regulated the power on this engines when they increased/decreased in speed, i suppose it was some kind of valves wich you could adjust the steamflow to the turbines with, and in that case what type of valves was it and how many could it be on a big ship like Bismarck?

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marcelo_malara
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Steam turbine

Postby marcelo_malara » Sun Oct 02, 2005 11:20 pm

Hi, I undertstand that there is a valve located in the steam pipe that brings the steam from the boiler room to the engine room, so the pressure of steam can be regulated to set the speed of the turbine.

Captain Morgan
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Postby Captain Morgan » Fri Jul 21, 2006 2:17 pm

You monitor shaft speed for the screw and open the throttle valves to get to the desired speeds. The orders from the bridge could be by telegraph (the dial showing the desired speed, or they can tell you to make turns for 20 knots etc. You then open or close the throttles as necessary to make the turns (rpm's)
There are 2 types of vessels out there. One type is called a target. If it isn't capable of silently doing 30+ knots at 2000 ft depth its always considered a target. The vessel that can silently go fast and deep is the one the targets are afraid of.

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glugn
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Re: Steamturbine engines!

Postby glugn » Fri Dec 23, 2011 8:15 pm

Something that has always interested me: the physical differences between single & double reduction geared turbine engines. The US used double reduction gears while Europeans used single. Given the generally better performance of the double reduction geared turbines, how difficult would it have been to replace a single reduction geared engine w/ a double reduction geared engine?

All other things remaining the same, what would the effect be in terms of increased speed & fuel consumption?

Just curious....
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dunmunro
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Re: Steamturbine engines!

Postby dunmunro » Fri Dec 23, 2011 10:48 pm

glugn wrote:Something that has always interested me: the physical differences between single & double reduction geared turbine engines. The US used double reduction gears while Europeans used single. Given the generally better performance of the double reduction geared turbines, how difficult would it have been to replace a single reduction geared engine w/ a double reduction geared engine?

All other things remaining the same, what would the effect be in terms of increased speed & fuel consumption?

Just curious....


The effect of DR gearing was to allow for lower propeller speeds and higher turbine speeds. Lower propeller speeds allowed for the use of larger props which were more efficient at low cruising speeds, while higher turbine speeds allowed for smaller turbines, that generated more power through increased RPM. However, in the absence of variable pitch props, a DR gear power-plant wasn't necessarily more efficient than a SR plant at mid to high power, as a comparison of Vanguard to Iowa shows:

Full power specific fuel consumption trials condition;


Iowa = .647 in 1943 (221020 shp 4 shafts, 8 boilers, 565psi/850f,DR gearing, .627 average from 80,000 to 221000shp) ( from http://www.navweaps.com/i...h-104_BB61_Sea_Trial.pdf )

Vanguard = .63 in 1946, average from 60000 to 136000 shp (136000 shp, 4 shafts, 8 boilers, 400psi/700f, SR gearing) (stated in British BBs, G&D state .64)

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glugn
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Re: Steamturbine engines!

Postby glugn » Mon Dec 26, 2011 2:55 pm

So then there wouldn't be an improvement in speed if SR gearing was replaced w/ DR I take it?
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Thorsten Wahl
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Re: Steamturbine engines!

Postby Thorsten Wahl » Thu Dec 29, 2011 7:30 pm

.627
wich unit of measurement?
Meine Herren, es kann ein siebenjähriger, es kann ein dreißigjähriger Krieg werden – und wehe dem, der zuerst die Lunte in das Pulverfaß schleudert!

dunmunro
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Re: Steamturbine engines!

Postby dunmunro » Fri Dec 30, 2011 12:02 am

Thorsten Wahl wrote:
.627
wich unit of measurement?


Lb/shp/hr

dunmunro
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Re: Steamturbine engines!

Postby dunmunro » Fri Dec 30, 2011 12:08 am

glugn wrote:So then there wouldn't be an improvement in speed if SR gearing was replaced w/ DR I take it?


Not at the same SHP (assuming that both plants used props optimized for speed). However, the reduced weight and volume of the DR PP could be used to provide more power for a given weight and volume.

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glugn
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Re: Steamturbine engines!

Postby glugn » Fri Dec 30, 2011 2:07 pm

Ahh. OK. So there would be a size & weight advantage to DR gearing then. Interesting. Thank you.
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lynn1212
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Re: Steamturbine engines!

Postby lynn1212 » Mon Feb 20, 2012 2:00 am

i used to work for a company that made gear sets for many different uses including ships. we produced the drive sets for the class of LSTs built for the USN back in the sixties and seventies. double sets were smaller both in size and weight as well as having higher power ratings and larger ratios. however they required a better tech base and machines [not to mention machinists]. every set we built had to pass a stall test where the torque levels were measured in foot tons , 2 500 hp dc motors coupled in tandem to the input shaft and a beam with a scale anchored to the output. in other words locked in position. our 250vdc generator sets didn't like it a bit. the advantage of double sets comes from the ability to use smaller gear pairs to get large reductions. two 4 to 1 pairs requires just 3 shafts, six bearings and gives a 16 to 1 reduction. a 16 to 1 single set would be about 4 times bigger since the output gear would have to be 16X the diameter of the input gear instead of the 4x needed in the double set. larger footprint, heavier, much taller, harder to lubricate, case needs to be built heavier, and the whole thing is more apand t to suffer shock damage as well as being much harder
repair in place or to replace. there is also a large difference between the types of gears used. we used a type called a Sykes herringbone gear. it was a double helical gear with a groove between each half and each tooth was curved so the load was spread over 2 or 3 teeth at a time instead of 1 or 2. this resulted in a much stronger gear and it also ran a lot quieter and resulted in a smaller set. we also used tapered bearings with thrust bearings on the output shaft as well. often overlooked are the oil requirements and cooling. water and gunk will screw up a set real quick. as an aside we cut gears up to 27 feet in diameter and up to a 6 foot face. big impressive hunks of steel

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Re: Steamturbine engines!

Postby Byron Angel » Mon Feb 20, 2012 1:12 pm

lynn1212 wrote:i used to work for a company that made gear sets for many different uses including ships. we produced the drive sets for the class of LSTs built for the USN back in the sixties and seventies. double sets were smaller both in size and weight as well as having higher power ratings and larger ratios. however they required a better tech base and machines [not to mention machinists]. every set we built had to pass a stall test where the torque levels were measured in foot tons , 2 500 hp dc motors coupled in tandem to the input shaft and a beam with a scale anchored to the output. in other words locked in position. our 250vdc generator sets didn't like it a bit. the advantage of double sets comes from the ability to use smaller gear pairs to get large reductions. two 4 to 1 pairs requires just 3 shafts, six bearings and gives a 16 to 1 reduction. a 16 to 1 single set would be about 4 times bigger since the output gear would have to be 16X the diameter of the input gear instead of the 4x needed in the double set. larger footprint, heavier, much taller, harder to lubricate, case needs to be built heavier, and the whole thing is more apand t to suffer shock damage as well as being much harder to repair in place or to replace. there is also a large difference between the types of gears used. we used a type called a Sykes herringbone gear. it was a double helical gear with a groove between each half and each tooth was curved so the load was spread over 2 or 3 teeth at a time instead of 1 or 2. this resulted in a much stronger gear and it also ran a lot quieter and resulted in a smaller set. we also used tapered bearings with thrust bearings on the output shaft as well. often overlooked are the oil requirements and cooling. water and gunk will screw up a set real quick. as an aside we cut gears up to 27 feet in diameter and up to a 6 foot face. big impressive hunks of steel



..... Fascinating insights, Lynn. Thanks for posting same. I once had the privilege of being in the machinery spaces of BB59 and was able to actually view one of her sets of reduction gearing close-up. As I recall, it is about the size of a large refrigerator lying on its back - remarkably small, really, considering the great amount of power and torque that pass through such a device. The reduction gear casing had been fitted with a transparent inspection cover, making it possible to actually view the internal gearing. The gearing assembly was, without question, a masterpiece of precision machining that belong in an art museum. The workmanship is all the more impressive when it is realized that it was all done without the aid of computer-control.

B


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