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楼主: mettle

[技术] 美国密歇根州威廉姆斯研究所制造的WR24-7-2型发动机

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 楼主| 发表于 2018-1-5 21:10:57 | 显示全部楼层

WR24-7-2型发动机

WR24-7-2型发动机

That’s a mighty complex part, an integral cast/welded/brazed/machined construction that forms the rear combustor liner, the aft combustor labyrinth seal, the hot air duct to the turbine nozzle guide vanes (NGV), the hollow pre-swirl vanes and air ducts to the rear of the combustor, and finally the NGV itself. I guess if this component has to be replaced, things get expensive ;-).

WR24-7-2型发动机

WR24-7-2型发动机

That’s a view of the NGV side of the assembly, also the labyrinth seal is clearly visible.

WR24-7-2型发动机

WR24-7-2型发动机

This photo shows the hollow pre-swirl vanes and the dilution air holes just in front of the “bend” to the NGV. It’s quite amazing that the whole combustor / NGV section of this engine is 100% identical with the corresponding parts of the WR2-6!

 楼主| 发表于 2018-1-5 21:12:11 | 显示全部楼层

WR24-7-2型发动机

WR24-7-2型发动机

The turbine wheel is a precision cast component and - just like the compressor - has MANY blades -- 53 if I remember correcly. It is permanently attached to the shaft, probably by electron beam welding.

WR24-7-2型发动机

WR24-7-2型发动机

The rear bearing is of the cylindrical roller type and once again, is of very high quality. The slots in the outer race mate with an alignment pin in the turbine bearing labyrinth seal that keeps the outer race of the bearing from rotating.

WR24-7-2型发动机

WR24-7-2型发动机

The combustor casing is a structural part of the engine and contains the rear bearing seat. This is also a very complex assembly of various pressed/stamped, cast and machined parts. Again, the components are welded/brazed together.

 楼主| 发表于 2018-1-5 21:15:39 | 显示全部楼层

WR24-7-2型发动机

WR24-7-2型发动机

Here the turbine shroud and the bearing cavity are shown.

WR24-7-2型发动机

WR24-7-2型发动机

The inner wall of the bearing cavity is perforated to permit the oil mist that enters through the hole in the rear wall, to escape through the three hollow struts that center the bearing seat inside the turbine shroud.

WR24-7-2型发动机

WR24-7-2型发动机

That’s the rear bearing labyrinth seal that basically prevents the hot exhaust gas behind the turbine wheel from entering the bearing cavity.

 楼主| 发表于 2018-1-5 21:16:44 | 显示全部楼层

WR24-7-2型发动机

WR24-7-2型发动机

That’s the last shot of the “walk through the engine” and reassembly of the unit will commence afterwards. It’s the rear bearing outer race vibration damper, a formed/ground spring steel part that centers the outer race of the roller bearing inside the bearing cavity while it still allows for a small amount of elastic radial displacement and angular alignment.

WR24-7-2型发动机

WR24-7-2型发动机

This photo shows the labyrinth seal/vibration damper/roller bearing stack as it’s supposed to be slided into the bearing cavity. Notice the alignment pin in the labyrinth seal mating with the slot in the bearing’s outer race.

WR24-7-2型发动机

WR24-7-2型发动机

The central labyrinth seal aligns the combustor front with the heat shield and the diffuser housing.

 楼主| 发表于 2018-1-5 21:17:43 | 显示全部楼层

WR24-7-2型发动机

WR24-7-2型发动机

The front of the combustor is in place.

WR24-7-2型发动机

WR24-7-2型发动机

The rear of the combustor has to be placed on the forward assembly while the hole for the spark plug has to be in the proper position and the slots have to mate with the sheet metal brackets. Well, finally everything is properly positioned...

WR24-7-2型发动机

WR24-7-2型发动机

The rear bearing section is put back together. A circlip holds the complete assembly in place.

 楼主| 发表于 2018-1-5 21:18:43 | 显示全部楼层

WR24-7-2型发动机

WR24-7-2型发动机

The radial compressor impeller has been heated and slided onto the shaft. Since it’s an interference fit, just pressing the impeller home would result in scoring of the bore and thus weakening of the whole structure.

WR24-7-2型发动机

WR24-7-2型发动机

The four-point bearing’s outer race is in place.

WR24-7-2型发动机

WR24-7-2型发动机

The radial compressor cover/bearing seat assembly has been put back in place and the alternator rotor is already slided onto the shaft.

 楼主| 发表于 2018-1-5 21:19:42 | 显示全部楼层

WR24-7-2型发动机

WR24-7-2型发动机

Here the axial compressor stator and alternator assembly has been returned into the proper position.Notice the carbon seal’s rotating member of the fuel seal assembly.

WR24-7-2型发动机

WR24-7-2型发动机

This photo shows how much bigger actually the turbine wheel is compared to the NGV shroud. The blades project by at least 2mm radially. Supposedly, this helps to reduce clearance losses at the turbine wheel periphery. Yet, this tends to increase turbulence losses at the “step”. Well, I guess there’s no such thing as a free lunch... ;-)

WR24-7-2型发动机

WR24-7-2型发动机

That’s the oil mist generator (OMG) opened.

 楼主| 发表于 2018-1-5 21:20:49 | 显示全部楼层

WR24-7-2型发动机

WR24-7-2型发动机

The lower section forms the oil tank and contains a drain port and the oil heater and thermostate switch. The heater will be activated if the engine has to be started at  very low temperatures when the viscosity of the oil may be too high to produce a sufficiently fine oil mist.

WR24-7-2型发动机

WR24-7-2型发动机

The left port is the oil filling valve, in the centre of the photos the sight glass is shown that permits checking the oil level.

WR24-7-2型发动机

WR24-7-2型发动机

The tube pointing to the left ducts the oil from the tank to the atomization venturi.

 楼主| 发表于 2018-1-5 21:21:47 | 显示全部楼层

WR24-7-2型发动机

WR24-7-2型发动机


WR24-7-2型发动机

WR24-7-2型发动机


Through the small nozzle at the base of the feed tube, the oil mist is ejected into the upper OMG cavity. All droplets bigger than a certain limit will settle on the metal parts or the baffle and drain back into the oil tank

WR24-7-2型发动机

WR24-7-2型发动机

Only the droplets that are small enough will enter the port opposite of the compressor delivery air input and enter the lubration system of the engine. Below, one of the compressor bleed air metering orifices is shown.

 楼主| 发表于 2018-1-5 21:22:57 | 显示全部楼层
Only the droplets that are small enough will enter the port opposite of the compressor delivery air input and enter the lubration system of the engine. Below, one of the compressor bleed air metering orifices is shown.

WR24-7-2型发动机

WR24-7-2型发动机

This sketch shows the operation of the OMG.

WR24-7-2型发动机

WR24-7-2型发动机

Finally the engine is back together in one piece. Enjoy the views from all sides...

WR24-7-2型发动机

WR24-7-2型发动机


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