Hi Gilles,
>Let's do a small "thought experiment" : if we have an adjustable valve
>at the end of the fuel line, couldn't we adjust fuel flow by screwing in
>or out the valve knob ?
>
I don't know where you want to go with this, but a restriction after the
pump would certainly decrease the generated flow.
The combination Pierburg pump plus restriction would constitute a new
pump with a graph of similar shape as the original.
A lower maximum flow at zero delivered pressure, the same maximum
pressure (1850 hPa) at zero delivered flow.
A restriction that lowers maximum flow (0 pressure) from 120 l/h to 53
l/h will not explain the huge difference between actual and published
though.
Such a restriction drops 1500 hPa at 53 l/h (operating point of the
published pump) or 28.3 hPa per l/h
At 39 l/h the published pump delivers about 1650 hPa, the restriction
then subtracts 39 * 28.3 = 1104 hPa.
Leaves you with 550 hPa at take-off fuel flow. The fuel regulator needs
up to twice that. Again - according to published figures.
Still don't know what to think.
Regards,
Jan de Jong
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