My Turn- Fault Finding

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JK
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My Turn- Fault Finding

Postby JK » Sun Aug 23, 2009 7:07 pm

The engine is a V-16 Wartsila. (I can't remember the model right now, I'll have to look it up.) The engine has a turbocharger per bank and a pulse exhaust.

Ship is in heavy ice, a lot of manuevering and the engines are working at their top end of power.
Without warning, one engine starts to "bark" from one of the turbos. It is like a machine gun going off in the engineroom, it is so violent, I thought that the turbocharger was going to disintegrate.
I shut the engine down and we spent the next 3 watches trying to sort out the problem.

Anyone know what we found?

Oh, and I know the same thing has happened on a MaK 453 V engine.

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ArkSeaJumper
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Re: My Turn- Fault Finding

Postby ArkSeaJumper » Mon Aug 24, 2009 1:46 am

I order for a turbo to bark the pressure in the scavange pressure has to be higher than the output of the compressor. When this happens (in my experence) there is a good long bark, as all the pressure in the scavange reciver dumps.
By the sound of yours it is very fast, as you say like a machine gun, so I would say one of the inlet valves jammed, allowing a pulse from that unit into the scav box.

But saying that I dont have a lot of experence with V engines.

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JK
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Re: My Turn- Fault Finding

Postby JK » Mon Aug 24, 2009 4:10 am

One of the first things checked, but they were fine.

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Re: My Turn- Fault Finding

Postby ArkSeaJumper » Mon Aug 24, 2009 5:25 am

1 Something blocked the aircooler, either completely sooted up, or parts of the air filter

2 The air filter / silencer collapsed, I have seen this, but it didnt cause the turbo to bark

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The Dieselduck
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Re: My Turn- Fault Finding

Postby The Dieselduck » Mon Aug 24, 2009 5:54 am

My guess is you were having problems with the waste gate mechanism. I have not heard this happen before but certainly would could the pressure difference.
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JK
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Re: My Turn- Fault Finding

Postby JK » Mon Aug 24, 2009 6:15 am

No, neither

This is a good one :wink:

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Re: My Turn- Fault Finding

Postby ArkSeaJumper » Mon Aug 24, 2009 6:20 am

You picked up a rope in the prop

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Re: My Turn- Fault Finding

Postby JK » Mon Aug 24, 2009 6:33 am

No, no rope.

The engine was a Wartsila Vasa32, burning MDO.
It may give you a little more info if you are familar with them.

Probably the nicest engine I have worked on for ease of maintenance.

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Re: My Turn- Fault Finding

Postby JK » Mon Aug 24, 2009 7:52 am

Hint:

You are only thinking of one side of the TC

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Re: My Turn- Fault Finding

Postby ArkSeaJumper » Mon Aug 24, 2009 8:05 am

Are you refering to afterburning?

I have seen the nozzle dirty enough to speed up the turbo, and cause barking, but this happen slowly, not a sudden machine gun effect

And I dont know this engine, (and not to fond of Wartsilas either)

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Re: My Turn- Fault Finding

Postby JK » Mon Aug 24, 2009 7:25 pm

I have seen this in the Wartsila and have heard of it happening in a MaK 16M453

The exhaust of each bank consists of 4 manifolds exhausting into the turbine nozzles. 2 cylinders feed each exhaust and this all balanced to provide constant pressure at the turbine.

We all immediately think that barking is caused on the compressor side, but in this case it was not so. After literally looking at every head, the intakes, cooler, we were at a loss to what the cause was. We finally started looking at the exhaust manifolds. What we found was that the manifolds have expansion bellows. Inside these stainless steel bellows are sleeves, welded in place. These sleeves keep the laminer flow of the exhaust gases. One of the sleeves had the welds fail and it went down the pipe and was flattened. It cut off the exhaust gas flow to the turbine on one nozzle which changed the speed of rotation rapidly. The compressor started surging. This sleeve would fall down in the manifold as the pressure dropped and as it built again would rise and jam the exhaust again and the cycle would start over.

All the engineers who worked on these Wartsila engines really liked them I think it was because we burn MDO and that takes a huge amount of work out of the job!

Another Turbo issue. Same engines.
The TC compressor inlet is directly ducted to the exterior, 3 decks above the engine. Engines work great, until the ship hits the Arctic and temperatures dropped to between -30 and -40*C. The ship is breaking ice and one engine in particular starts having the turbocharger surging. It is intermittant and no cause can be found.
What do you think it is?

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ArkSeaJumper
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Re: My Turn- Fault Finding

Postby ArkSeaJumper » Mon Aug 24, 2009 11:33 pm

Upon mature reflection I have had problems with the internals of these bellows before. Good One.

Cold weather is normally good for air volume, I assume there is no Ice build up, blocking the vents.

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Re: My Turn- Fault Finding

Postby Big Pete » Tue Aug 25, 2009 12:14 am

If the air is this cold then then the charge air "cooler" will be heating the charge air. We normally get surging and barking when the differential pressure on the the turbine compressor excedes the design limit of the compressor and the air flows first stalls, then momentarily reverses.
Was this anything to do with the cold air being compressed and then heated in the cooler causing it expand and the pressure to rise?
With the air this cold and dense, the mass flow of air probably excedes the design limits of the turbocharger. When the engine is running at full power this could overload the turbine side and cause the exhaust gas flow to stall.
Either way, I think drawing the air directly from the engine room would cure the problem.
Good problem JK.
It is always better to ask a stupid question than to do a stupid thing.

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JK
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Re: My Turn- Fault Finding

Postby JK » Tue Aug 25, 2009 4:25 am

Thats exactly what happened. Plus the duct was straight up for 3 decks so it was a columm of cold dense air sitting on the compressor intake. In that case, when the surging started you could actually see the ducting being sucked in on the sides. We took out a section of the duct and put wire mesh across the top.
Problem solved.

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Re: My Turn- Fault Finding

Postby astat101 » Thu Apr 30, 2015 4:49 am

Hi,

I have brieflt read through some of the posts and thought I would just mention there is a company that manufacture diesel engine charge air coolers, you should try Vestas aircoil A/S in Denmark (www.vestas-aircoil.com)

Maybe they can advise.


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