Very eye opening paper, especially to me are the actual percentages of aeration in the motor oil inside an engine. Years ago I witnessed Smokey Yunicks "smoketron" in operation and the oil volume due to aeration followed the studies figures. Smokey's motor ran a dry sump and the oil level in the viewing glass side reservoir jumped as the obviously foamed oil returned to it. You could clearly see the foamed oil on top and the honey like oil at the bottom that of course was heading for the pressure side of the dry sump pump and finally to the bearings, exactly why dry sumps are praised by the big name race engine builders who don't want shaving cream in their bearings.
I was disappointed in this study to not find out if aerated oil is in fact detrimental as far as wear on engines bearings (they offer two statements that only served to confuse the matter) Page 20 Sect 1.1.3.1 . I understand that aeration increases the viscosity of oil, I suppose the same as a milk shake which is aerated to the hilt. The fact that aerated oil acts as an insulator makes sense. I always think about the uselessness of aerated hydraulic fluids as far as their ability to support a load. I believe the oil film in rod bearings particularly at high rpm must resemble a hydraulic load on the oil film. Certainly an aerated oil film is more likely to compress and permit bearing to shaft contact where as pure un-aerated oil being only fluid can not compress.
Sadly the tested different designs of windage trays, three different mesh sizes and open hole etc, simply showed there was not a winner. To me that indicates that wire mesh and expanded metal both offer a very large void space (exactly what they are known for in filtration) which acts more as just a large opening to windage rather then a separator.. I'd bet that a large mesh/expanded metal surface area as in many trays, may in fact make matters worse as far a aeration. With the back and forth violent wind pulses around the crank and in the crankcase I'd expect the trays excessive openings to work just like a kids "soap bubble" stick making millions of bubbles and foaming the hell out of the oil. To me scrapers that act as graters to simply and selectively shear away the thin oil film itself from the trays surface that is thrown there by centrifugal forces without sending a windstorm down below into the sump area are the way to go. I had an opportunity to study a high zoot factory late model Vette windage tray and noticed no surprise how much Chevy had copied the factory Ford FE tray in their deep sided cross-bolted Y block. The Chevy tray utilized narrow grater slots to not only grab the oil coming off the trays down-wind surface by the blocks side, as does the factory FE tray, but ALSO Chevy utilized similar graters to skim off the oil coming down off the crankcases side at the opposite side of the tray. Obviously they are trying to grab foamed up oil droplets and not send a windstorm down into the sump. Just like this test showed, the mesh was essentially the same as an open hole or no tray.. If you have a windstorm in the bottom of your motors sump you're shooting yourself in the foot, defoaming the oil is literally all blown to hell. Obviously the Mfgs that took/take the factory FE tray design and installed expanded metal or metal mesh covered holes fail to understand what the FoMoCo engineers had designed. Personally I've taken the factory tray and slightly hammered down/reduced the height of the factory scraper blades to reduce the gulp taken and installed additional scrapers coming off the blocks side to get more of only an oil shot with minimal wind sent below. I admit I copied the Vette's tray design.
http://dspace.mit.edu/bitstream/handle/1721.1/38713/166145859.pdf
