Hysteric said

Something to consider:

Shrinker on the "Kill Bleed"

G'morning Shrinker,
So what happens with the opposite extremes? One case being too large of an air bleed (always atmospheric in the air well), and too large of a 'kill bleed' and/or e-holes above fuel level. The other case also being too large of an air bleed, but no kill bleed or upper e-holes.

Shrinker:

The Kill bleed is very important. It causes flow through the HSAB to occur BEFORE the booster vacuum is enough to lift the fuel to the outlet level of the metering block. Without the kill bleed you wont get any booster fuel until the vacuum is able to lift the fuel as per normal but once it starts it will come in real strong. The kill bleed flow is there to reduce the pressure in the main well and to make the pressure in the well transition to sequential jetting flow rules once the top e-bleed functions. The air pressure in the well is reduced by air flowing out of the well, and this is how it works--- the HSAB is the first jet in the air well system, the kill bleed is the second so the flow rate from it is sequential to the HSAB and then the top e-bleed gets uncovered and the area of flow is now doubled (it depends on the size of the e-bleed of course this is just an example). Now you have LESS sequential jetting effect. Once the next e-bleeds further down the block come in to operation you keep adding outlet area to the main air well so the sequential jetting rules may eventually not apply (depending upon sizing's etc).
Eventually you may reach the only jet being the HSAB itself.

The sequential jetting rule is this-- flow is restricted unless a downstream jet is greater than 4 times the area of the upstream jet.
Think about that for a bit.

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