Fuel Pressure

[Svein Lilleland]

>What about choked flow?  Maybe an orifice area term is needed for 
>really big changes in pressure.

>Derrick Early
>early at finite.nrl.navy.mil
>>really big changes in pressure.

Fluid flow through a nozzle is proportional to the area. An injector valve 
is, however, either open or closed, which implies that the nozzle area is 
not an adjustable parameter. With the response required for efi, do not 
contemplate a single proportional valve to control flow rate.

What might be possible is a proprtional device upstream of the injector 
valve. Varying the area of the proportional device, combined with a larger 
than required injector valve, could mean varying flow rate for a set time 
span. At high revs, when not much time is available,  increased effective 
nozzle area could provide the required increased flow rate. If this is 
economically feasible, I do not know. The idea just struck me as I was 
writing. Should probably have engaged the brain before the finger, but it 
sounds possible.

I started by stating that flow is proportional to nozzle area,  flow is 
proportional to the square root of pressure differential. Flow is further 
inversely proportional to the square root of fluid density, which is no big 
issue for fuel. Finally, flow is proportional to a discharge factor which 
typically is 0.62.

regards

svein.lilleland at hytrol.telemax.no