Power lossses in air intake 4

[48cmPiston]

Good day mu friends, I am back at en-tips with a new name and I know some can give an idea on this: In our new power plant I inspected the air intake for our engines and I found that the transition from rectangular to round was not well done and also we have internal plates that will cause turbulences. How can I calculate the power losses due to this 2 factors? Check the pictures. The power og each engine is 18 MW and any improvement will be of great help.-

 

[ivymike]

I assume this is a turbocharged diesel... in most cases w/turbocharged diesel there is no important effect on power through a wide range of intake restriction. Have you measured the total intake restriction (m H2O) at the turbo inlet when running at full power?

 

[48cmPiston]

Yes Mike, they are MAN 48/60 x 18 pistons turbocharged, and no, me haven´t yet measured them. We are about to start comissioning

 

[ivymike]

Well there are methods you can use to estimate the pressure drop through a duct, and you can find them in just about any fluids textbook as well as on a number of internet calculators / engineering toolbox sites.

The important thing is to compare the intake restriction to the allowable restriction figure from the manufacturer and have a figure less than the limit. Your power will not be impacted (for any diesel engine I've seen) within the manufacturer's restriction limits.

 

[48cmPiston]

Thanks again Mike, but as I still don´t have any flow in the ducts I am looking for... maybe an online simulator that could predict the losses...I know there is software also, but I would need first an article which I still didn´t find that covers this matter that proves it is important to keep looking...

 

[1gibson]

Correct me if I'm wrong, but due to the turbochargers achieveing a set manifold pressure regardless of inlet pressure, your power output should not change when you go from good to great inlet conditons. You may gain a small amount of effiency with better ducting, but is that worth the effort of redesign?

 

[ivymike]

when you say you don't have any flow... you mean you don't know what the required flow is? That should be available on a technical data sheet for the engine. If the manufacturer hasn't provided one, then call them back.

http://www.engineeringtoolbox.com/sizing-ducts-d_207.html

 

[48cmPiston]

@ Gibson, that´s exactly what I want to know. In our case 1% improvement would mean a lot of power increase

 

[48cmPiston]

@ Mike: I mean the engines are not operating yet, but until in a couple of months

 

[IceStationZebra]

Correct me if I'm wrong, but it looks like a round pipe ducted into a much larger box? If so then the only real power loss is going to be the square edge at the pipe entrance. ISZ

 

[berkshire]

So what is to stop you from changing that horrible looking adaptor to a square to round fitting?
B.E.

The good engineer does not need to memorize every formula; he just needs to know where he can find them when he needs them. Old professor

 

[Tmoose]

If the "not well done" intake system is factory supplied equipment I'd wonder about the possible impact on the engine warrantee.

"In our case 1% improvement would mean a lot of power increase."
So, you should have bought larger/more powerful engines ?

 

[GregLocock]

Typical pressure drop in an automotive intake system is around 0.5 kPa, and crude flow rate is obviously engine capacity*rpm/60/2 for a 4 stroke. So the power loss is easy to work out. So if you do have a 1% (~1 kPa) pressure drop you really have done a bad job, or have serious filters.

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376

http://eng-tips.com/market.cfm?

 

[catserveng]

Are these ABB turbo's, if so you might find these articles helpful,

http://www05.abb.com/global/scot/sc...abb turbocharging_operating turbochargers.pdf

ABB had a pretty good inlet air piping design guide at one time, I haven't been able to find a copy. MAN used to have a prety good installation guidebook that included inlet air piping design recommendations. If the turbo's are provided by someone else, you might see if they have published inlet piping design guidelines.

Mike L.

 

[ivymike]

Greg, that sounds like the right answer for an engine that's trying to keep AFR near stoich... These diesels won't necessarily change fueling at all in response to inlet restriction, and so the effect on power will be less.

 

[GregLocock]

Sorry yes, plus of course turbos add another multiplier.

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376

http://eng-tips.com/market.cfm?

 

[Tmoose]

I'd think carbs with bowls vented to carb throat and FI with mass flow sensors (not to mention O2 sensors) would compensate automatically for quite a range of inlet restriction. All my old dirt bikes have carbs with external bowl vents, so I expect respond by enrichening at very high airflows and filter restricition. But I have a picture showing the twin pipe CZs might have run their bowl vent lines to the clean side of the airbox. Every car I've seen back to the 50s bowl vents to the carb throat, but may have an extra vent but only that opens to atmosphere to relieve pressure from sitting when hot and prevent flooding.

 

[ivymike]

@tmoose - they would maintain AFR to the extent that they could, and that would result in less air/fuel in the cylinder and less power as a result. The diesels will still be injecting/burning the same amount of fuel, and always have excess air available, so the impact will be substantially less.

 

[48cmPiston]

@ Berkshire: what sotps us is those are huge filters and delivery would take more than 6 months, what I am looking is for information on power losses maybe from some similar cases and then prove my company that we should or not invest in improvements in the ducts. Maybe by installing deflectors to improve the flow.

@catserveng: this are MAN turbos but they are not the problem, the filters are from another brand and the problem is the reduction from retacngular to round which is not well done, the brand is Clarkor Uk model autoflo

 

[48cmPiston]

@Ice: it would be the square corners of the rectangular duct and the structural 4" plates installed inside the ducts