055 DDG Large Destroyer Thread

[taxiya]

I saw some talks about the deck layout around the aft VLS area. So I borrowed a photo and made my illustration below.
The left side is my understanding. The light blue is the weather deck (right term?)
Here is why I understand this way.

From this understanding I am almost certain that the aft VLS is smaller than the front, meaning 48 missiles, because the lower aft deck is only slightly wider than the VLS complex, meaning it does not block the view of the VLS in the first photo, meaning very small space between the front edge of VLS and the lower aft deck. In other words, we are seeing the whole aft VLS to the front corner.

 

[latenlazy]

Who said the type 055 had separate GT driven generators?

Typically even gas turbine powered warships uses diesel generators rather than separate gas turbines for powering generators.

A more precise way to ask the question is are those generators separate and independent systems from the gas turbines?

 

[taxiya]

Who said the type 055 had separate GT driven generators?

Typically even gas turbine powered warships uses diesel generators rather than separate gas turbines for powering generators.

good question.

So far, what I heard is some good diesel powered generators. Even if 055 use GT powered generators, 6 would be excessively and unnecessarily complicated, why not 2 more powerful GT which China does have?

One thing mentioned by Ma Weiming in his article is that it is a great challenge to cope many power sources (GT or diesel engines) together for electricity generation because all of them have to run at the same speed (at the end to alternator), same phase. Any difference, even small, can lead to significant decrease of efficiency (bad power waveform) or even destroy the generator and power grid. The less power source, the better, except redundancy requirement, 2 would be the optimum choice.

 

[Iron Man]

Wait. Are we sure the 6 generators have their own turbines, and aren't being driven by the 4 main turbines?

Essentially yes. While there is no physical law against a GT outputting power (mechanically) to both a transmission and an alternator, I do not know of a single example of a ship that does this. You would almost certainly need separate clutches and reduction gearboxes for each, thus increasing weight, space, and expense and probably significantly decreasing efficiency to boot. The only exception is the one that I mentioned earlier, the combined-cycle GT, which instead of leaching power from the output shaft, uses waste heat to power a separate steam turbine which runs a generator that produces electricity.

Who said the type 055 had separate GT driven generators?

Typically even gas turbine powered warships uses diesel generators rather than separate gas turbines for powering generators.

While there are certainly more GT-engined ships that use diesel generators than GT generators, it is definitely not a universal truth. Off the top of my head I can think of several ships that use GT-engined prime movers that in addition use smaller GT generators for electrical power instead of diesel generators: Arleigh Burke, Ticonderoga, Kidd, KDX-3, Daring, Zumwalt, Slava. I can probably find more. Not only that, the 055 video clearly shows 4 large GTs amidships with 2 triplets of smaller GTs forward and aft. You can tell the difference between a GT and a diesel by the large air intake and exhaust ports on the box housing structures that take up essentially all of the width of the box housing.

good question.

So far, what I heard is some good diesel powered generators. Even if 055 use GT powered generators, 6 would be excessively and unnecessarily complicated, why not 2 more powerful GT which China does have?

One thing mentioned by Ma Weiming in his article is that it is a great challenge to cope many power sources (GT or diesel engines) together for electricity generation because all of them have to run at the same speed (at the end to alternator), same phase. Any difference, even small, can lead to significant decrease of efficiency (bad power waveform) or even destroy the generator and power grid. The less power source, the better, except redundancy requirement, 2 would be the optimum choice.

Well it is already essentially a fact that the 055 has 6 GT generators, if the graphic in that video is correct. 6 GTGs allow you to more finely tune how much power to input into the grid, more than 4 or 2 anyway. It may also be that 6 GTGs most efficiently utilize the available space at the bottom of the ship (lowest deck area).

 

[Iron Man]

I saw some talks about the deck layout around the aft VLS area. So I borrowed a photo and made my illustration below.
The left side is my understanding. The light blue is the weather deck (right term?)View attachment 42442
Here is why I understand this way.


From this understanding I am almost certain that the aft VLS is smaller than the front, meaning 48 missiles, because the lower aft deck is only slightly wider than the VLS complex, meaning it does not block the view of the VLS in the first photo, meaning very small space between the front edge of VLS and the lower aft deck. In other words, we are seeing the whole aft VLS to the front corner.

Yes, this is why the line drawing on the right is wrong. As drawn the forward yellow line as I said before extends an entire deck below the weatherdeck and is not by any means coplanar with it.

 

[A.Man]

PLAN could be able putting these missiles on 055 destroyers. There are 4 large VLS's on the ship.

 

[Tyloe]

So after digging around it seems those CAD modelled boxes are mostly likely GTGSs as first suggested. The vent arrangement of a GTGS has the intake closer to the centre and the exhaust port at the end where the GT sits. Although the model of the air intake vent could be off on the 6 furthest aft and forward boxes, they should be including the generators while the large vents are key feature of GTs, thus their likely complete models of GTGSs.

 

[Iron Man]

So after digging around it seems those CAD modelled boxes are mostly likely GTGSs as first suggested. The vent arrangement of a GTGS has the intake closer to the centre and the exhaust port at the end where the GT sits. Although the model of the air intake vent could be off on the 6 furthest aft and forward boxes, they should be including the generators while the large vents are key feature of GTs, thus their likely complete models of GTGSs.

Yes, now you're essentially up to speed. The only thing to point out is that the business end of the GT (the output shaft) can come out either the intake side of the GT or the exhaust side, so there is no guarantee that the air intake and exhaust ports that you depicted for the GTGs are correct; they could be the other way around. This may or may not be a clue but the larger port seems to indicate intake rather than exhaust, if we go by the example of the LM2500 box housing in your diagram. The air intake and exhaust ports for the GT engines on the other hand are quite obvious, as well as which end the output shaft is coming out of, so there is no ambiguity there.

 

[Tyloe]

Yes, now you're essentially up to speed. The only thing to point out is that the business end of the GT (the output shaft) can come out either the intake side of the GT or the exhaust side, so there is no guarantee that the air intake and exhaust ports that you depicted for the GTGs are correct; they could be the other way around. This may or may not be a clue but the larger port seems to indicate intake rather than exhaust, if we go by the example of the LM2500 box housing in your diagram. The air intake and exhaust ports for the GT engines on the other hand are quite obvious, as well as which end the output shaft is coming out of, so there is no ambiguity there.

So for now 055's GTGS with its output shaft from the exhaust side sounds the most plausible then. Given there's no vent system shown in the CAD model, while the Burke's GTGS intake's definitely faces aft with the crossing vents, and a larger duct provides the large volume of air the GT accelerates. If that's the case then the air intake and exhaust vents of aft GTGSs would need to cross each other like with Burke's forward GTGSs.

 

[taxiya]

Well it is already essentially a fact that the 055 has 6 GT generators, if the graphic in that video is correct. 6 GTGs allow you to more finely tune how much power to input into the grid, more than 4 or 2 anyway. It may also be that 6 GTGs most efficiently utilize the available space at the bottom of the ship (lowest deck area).

What type of GT (for generators) would you guess they are? Power range? We have heard some types, but I can't figure out which one can fit in this picture.