Advanced Combustion and Energetics Lab Research Engine

[Blake11911]

Hello all

I am a Researcher in Penn States Advance Combustion and Energetics lab and we have recently committed to automotive fuel research, in particular otto cycle and SI engines, we currently are looking for an engine to instrument and modify so that we are able to use a camera to watch the compression process, spark ignition, and flame propagation. I have had a rather difficult time finding an engine that we could modify to fit our needs, the problem being the fact that engines today all use hemispherical engine heads. The primary issue with this is that when our piston is top-dead-center and fully compressed, the spark ignition and "first light" will all occur in the fine space between the piston and the hemispherical head. Due to this we would not be able to capture it all with our high speed cameras. My question is not necessarily of an engineering nature but of the experience of this forum, I am looking for an engine with a flat head so that when we replace the cylinder block with our transparent material we are able to watch the entire combustion process. Overhead Cam / Overhead Valve is not a 100% necessity, but is preferred.

In your experience have any of you encountered a single cylinder engine capable of such modifications?

Thank You

 

[BrianPetersen]

Old lawnmowers generally have flat-head engines with the valves in the cylinder block, and the cylinder head is completely unobstructed.

But ... Flat-head engines are obsolete for all manner of performance, emissions, and fuel consumption issues, which means that doing your research on an engine of that type might not necessarily be representative of actual production engines going forward.

I am not sure what you mean by "... replace the cylinder block with our transparent material". Where's the piston, where are you trying to watch from. If the "cylinder block" is transparent then why is a hemi- or pentroof-head an obstruction? Maybe we need a diagram of what you are trying to do.

Traditional small-block Chevrolet V8 engines have all the valves in a straight row. So do Volkswagen 4-cylinder 8-valve engines (the 2.0 litre base model engine used in base model Golf/Jetta for decades). So did the Chrysler K-car engine (which was based on the VW design). There are plenty of others. But the combustion chamber is in the head. Again, I don't know if it helps you because I don't understand what you are trying to do.

If you are looking for a flat bottom surface of the cylinder head with the valves perpendicular and the combustion chamber in the piston - most modern diesels are like that, but that's a different combustion process which doesn't help you. The 12-valve Volkswagen VR6 was like that, as was the old Chevrolet 348 and 409 V8 engines, which went out of production in the 1960s. This arrangement wasn't great for combustion efficiency, which is why it's no longer used.

 

[anyoldname]

Blake,

I work with a powertrain design & development consultancy and have designed several optical engines for use researching combustion process fundamentals. Our optical solution overcomes the issues you describe with the hemispherical combustion chambers and has been used successfully for both our own combustion system development and also at several leading universities. It can be used on a wide range of modern SI & DI cylinder heads (although we need to check out each engine's cylinder head geometry before saying that its 100% compatible).

We have several different approaches to this type of hardware, depending on the type and range of different engines that are to be tested on a single base engine/rig. These range from using most of the standard engine components and adapting them for optical access, which is the cheapest option, to our custom designed base engine that can be adapted to a wide range of cylinder bores and strokes. The latter is the most expensive initial investment but offers easy adaption to different configurations and can be operated over a very wide range of speed and load conditions.

What type of program are you aiming to use this engine on? Also, are there any particular aspects of combustion that you want to examine and what type of optical / measurement techniques are you intending to use?

If you can answer me on here then I'll figure out a way of sending you my work details.

Thanks.

 

[tbuelna]

Your comment "replacing the cylinder block with our transparent material we are able to watch the entire combustion process" caught my attention. Can you provide more details of this cylinder block design?

One issue you face is that it can be difficult to get high quality images of combustion flame propagation in all directions from a single lens location. Normally SI combustion images are taken from at least two different orientations so that effects like intake charge motion (swirl, tumble and squish) can be evaluated.

If the intake charge motions produced by the port shapes are not an issue, you can probably use a 4-stroke DI diesel engine head and modify the injector port with some sort of bushing to accept a spark plug. Most 4-stroke DI diesels have flat head decks with 4 valves and use a centrally located injector hole. The DI diesel heads also usually have a glow plug port that is convenient for installing instrumentation like a pressure transducer.