engine stress

[scorcher1980]

i am interested in knowing how I should go about finding the maximum stress in combustion chamber of a diesel engine. the material will be pearlite.

can anyone plase help me with this?

Regards

Raam Shanker

 

[Fabrico]

Don't forget to include the morons who start them with ether.

 

[GregLocock]

That's not a bad approach. Work back from the forces in the cylinder head bolts.

Cheers

Greg Locock

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.

 

[MikeHalloran]

Okay, I'm a moron.

How do _you_ start a stone cold Diesel at -20F?



Mike Halloran
Pembroke Pines, FL, USA

 

[waross]

Hi Mike.
Detroit Diesels used to have a miniature oil burner that installed in place of one of the handhole covers on a 71 series engine. It lit a small fire in the air box.
I have had to start "Stone cold diesels" at -20 without ether.
Some start quite well with the glow plugs. Some don't.
Some require glow plug heating times several times longer than recommended. Sometimes a lot of batteries and jumpers are involved. Some engines required the intake manifold to be heated with a propane torch prior to cranking.
Well charged batteries in good condition are a must.
respectfully

 

[Zapster]

There is nothing wrong with starting diesel engines with starting fluid in cold weather provided the engines are not equipped with glow plugs. Many pieces of equipment have remote starting fluid injection systems so you don’t even need to open the hood. Just push the button from the cab to inject starting fluid directly to the intake manifold. My old JD farm tractor came with a remote starting fluid injection system as a factory option.

 

[Majik]

there's an art to a light dusting of ether into the chamber instead of a hard ring breaking spray.

 

[kenre]

I remember one particular brand of starting aerosol can contained over 40% ether, the more well know brand at the time had only 15% in comparison. the strong stuff made diesels sound like they had cylinders full of ball bearings when used.... One particular engine used to get a big wiff of the stuff by the apprenti, i always stood clear when the key was turned.

Ken

 

[EngJW]

Back to the question, this has got to be a very difficult thing to calculate because you have both pressure and temperature loads, plus localized loads from the head bolts. I can't think of any way other than a finite elephant analysis, and that will only be as good as how accurately you model the loading. Your model of the head will have to be limited in detail to save on computer time. After all this effort, a head that passes the analysis might end up failing at a thin wall, an insufficient fillet, or a hot spot.

You could do the finite element and then follow it up with testing, or you could use the old "rules of thumb" and then test it.

You can also optimize the design and then have the foundry tell you they can't cast it.

 

[MikeHalloran]

This was a Detroit Diesel four- stroke. We had no way to heat the air or the engine. What decided it for me was a priming cup in the air cleaner, with a spring loaded cover. What other possible use could it have?



Mike Halloran
Pembroke Pines, FL, USA

 

[EdDanzer]

Preheating the fuel works better than any other solution we have seen. Using either in a Yanmar air cooled diesel will damage rings, pistons and rod bearings. Cold diesel does not form the correct spray for starting.

 

[GunMuse]

Dipstick oil heaters, and coolant heaters are just a requirement in cold weather.

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