enginehistory.org

[cmalott]

Of all the WWII German A/C engines that were direct injection, BMW, MB, etc., did any of them do their injection on the compression stroke after the intake valve was closed? Apparantly the U S engines, 3350s and 4360s that were DI, did their injecting on the intake stroke. The same goes for DI MB auto engines of the 50s and 60s. Most all of the present auto engines are port injectors. But presently there are at least two 2 stroke outbaord motors that use high pressure direct injection on the compression stroke. The fuel is injected without the help of an airblast to mix it up. How they manage to get the gasoline mixed up well enough for spark ignition would seem like a challenge.

[szielinski]

The aim of direct injection in two-strokes AFAIK is to reduce the THC emissions; by waiting until the exhaust port is closed very little is blown out the exhaust port.
With four strokes the advantage of injecting as soon as possible is that the fuel has more time to evaporate and assist charge cooling.
I have a .pdf document that discuses a direct injection method quite well (send a PM and I will e-mail it if you like).
Alternatively you could try looking up the Linearised Instability Sheet Atomisation (LISA) modelling technique for spray injection.
Also, if you are able to look at any documentation/diagrams regarding the Crecy engine, the injector nozzle changed the spray pattern depending on pressure. When the piston was near the bottom of the stroke it sprayed a long stream down the bore, and vice-versa.
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“Make everything as simple as possible - but not simpler” – Einstein.