djones wrote: ↑29 Feb 2020, 17:33
I read somewhere about manipulating the sensor with temperature.
Can anybody explain how such a thing would work as I'm struggling to visualise this?
I am wondering the same thing!! Was thinking about it today and come up with following idea. I only done basic fluid dynamics for years ago and have no knowledge about fuel chemistry, so whoever more comfortable in these fields should comment on this. I also didn't check whether this would be ok within regulations.
So my basic understanding is that the flow sensor is a device measuring the fuel flow at some point by Measuring velocity and with a known area of the intersection one will get flow in volume, then by a inversion you get the kg/minute or flow in weight.
Why is it in weight? I guess that the temperature of the fuel does effect density and thus energy/volume but not energy/weight. But then one would need to calibrate the sensor to temperature as well as engine manufacturer, if i remember correctly they do use different fuels.
Is this varying temperature actually taken into account? I don't know.
If yes, where is this temperature measurement taken? I don't know.
If there is no measurement but temperature effects density, sending in cooler fuel will make the flow sensor measure less flow then actual. If the measurement is taken way before, one could put some of it through a acooling system and gain the same effect.
An other way to trick it could be changing the viscosity of the fuel. If temperature change also induces a viscosity change, the same cooling/heating system could lead to the boundary later decreasing and giving a higher flow for same velocity.
Let me know what comments you have, and point out where I am wrong on the reasoning!