Possible limits, tricks and cheats of the flow sensors?

[j.yank]

Changing the modulus of the fuel will not change the density.

In a fluid, the bulk modulus K and the density ρ determine the speed of sound c (pressure waves), according to the Newton-Laplace formula
https://en.wikipedia.org/wiki/Bulk_modulus

Obviously, if you wish to keep the speed of the sound in given medium constant (as reqiired by the F1 regulations regarding the flow sensor), bulk modulus and density are interlinked.

AFAIK the flow sensor is not sensitive to the speed of sound in fact it calculates the speed of sound of the medium.

To calculate the speed of the fliud it must first check the speed of the sound in this fluid. This is done sending ultrasound pulses in both directions, and the delta between them gives you the speed of the fluid, but you must have the speed of the sound in this fluid as a reference. That's why in the technical regulations they speak about calibrated fuel sensors.

[Tommy Cookers]

.....That's why in the technical regulations they speak about calibrated fuel sensors.

Gill seems to claim (what they call) accuracy of 1%
isn't that equivalent to one NA car being limited to 2400cc capacity but another being allowed 2424 cc ? (or 2376 and 2424 ?)
unsteady flow measurement isn't easy

due to viscosity fuel molecules near the pipe wall will be moving slower than those near the middle of the flow
not even a Gill meter can measure the speed of every fuel molecule
ie different fuels will have different velocity profiles

isn't that 2 reasons for individual competitor fuel-specific FIA calibrations ?

btw
about 25 years ago my boss briefly asked me about this product
I said wte our internal customers amounted to a centre for (informed) scepticism about any kind of flow measurement

[j.yank]

.....That's why in the technical regulations they speak about calibrated fuel sensors.

Gill seems to claim (what they call) accuracy of 1%
isn't that equivalent to one NA car being limited to 2400cc capacity but another being allowed 2424 cc ? (or 2376 and 2424 ?)
unsteady flow measurement isn't easy

due to viscosity fuel molecules near the pipe wall will be moving slower than those near the middle of the flow
not even a Gill meter can measure the speed of every fuel molecule
ie different fuels will have different velocity profiles

isn't that 2 reasons for individual competitor fuel-specific FIA calibrations ?

btw
about 25 years ago my boss briefly asked me about this product
I said wte our internal customers amounted to a centre for (informed) scepticism about any kind of flow measurement

This is what I found about the flow sensors: https://www.racecar-engineering.com/tec ... ters-work/

[gruntguru]

In a fluid, the bulk modulus K and the density ρ determine the speed of sound c (pressure waves), according to the Newton-Laplace formula
https://en.wikipedia.org/wiki/Bulk_modulus

Obviously, if you wish to keep the speed of the sound in given medium constant (as reqiired by the F1 regulations regarding the flow sensor), bulk modulus and density are interlinked.

AFAIK the flow sensor is not sensitive to the speed of sound in fact it calculates the speed of sound of the medium.

To calculate the speed of the fliud it must first check the speed of the sound in this fluid. This is done sending ultrasound pulses in both directions, and the delta between them gives you the speed of the fluid, but you must have the speed of the sound in this fluid as a reference. That's why in the technical regulations they speak about calibrated fuel sensors.

???
You say "it must check the speed of sound in the fluid" then "you must have the speed of the sound in this fluid as a reference".

No need for a reference sonic velocity if the sensor can measure it for itself - which it certainly can do. For example it would be trivial to measure travel time in the fluid during zero flow conditions.

[j.yank]

AFAIK the flow sensor is not sensitive to the speed of sound in fact it calculates the speed of sound of the medium.

To calculate the speed of the fliud it must first check the speed of the sound in this fluid. This is done sending ultrasound pulses in both directions, and the delta between them gives you the speed of the fluid, but you must have the speed of the sound in this fluid as a reference. That's why in the technical regulations they speak about calibrated fuel sensors.

???
You say "it must check the speed of sound in the fluid" then "you must have the speed of the sound in this fluid as a reference".

No need for a reference sonic velocity if the sensor can measure it for itself - which it certainly can do. For example it would be trivial to measure travel time in the fluid during zero flow conditions.

Each fluid has its own bulk modulus. That makes possible at given presure and speed of sound to control the density and to be sure that the mass flow will not exeed the regulated limit. If you calibrate the flow sensor to different fuel you will end with a different mass flow. So, the flow sensor must have as a reference the speed of sound in given fluid and then to check whether the actual speed of sound in the fluid match this reference. If not, the fuel is not gasoline, or it desn't have the defined by the regulations density.

[wuzak]

For a fuel to be used at a race it has to be approved by the FIA.

The FIA run several tests on the fuel to make sure that it is within the rules. They run a gas chromatograph test and create a "fingerprint".

At each race all the teams submit a sample of the fuel they are using to be tested by the FIA. The fuel has to match the "fingerprint" of an approved fuel.

Samples are also taken after qualifying and the race, and these too have to match the approved fuel specification.

I'm not sure this leaves much scope for gaming the fuel flow sensor by changing the fuel's bulk modulus.

The fuel flow sensor is calibrated so that a given output represents a certain mass flow rate. This may also take into account the fuel temperature.

[j.yank]

For a fuel to be used at a race it has to be approved by the FIA.

The FIA run several tests on the fuel to make sure that it is within the rules. They run a gas chromatograph test and create a "fingerprint".

At each race all the teams submit a sample of the fuel they are using to be tested by the FIA. The fuel has to match the "fingerprint" of an approved fuel.

Samples are also taken after qualifying and the race, and these too have to match the approved fuel specification.

I'm not sure this leaves much scope for gaming the fuel flow sensor by changing the fuel's bulk modulus.

The fuel flow sensor is calibrated so that a given output represents a certain mass flow rate. This may also take into account the fuel temperature.

Yes, it does: the bulk modulus reflects the specific space between atoms and molecules of given fuel at given temperature. Of, course, if you find a way to alter this space without changing the temperature, you will have the same fuel with the same chemichal composition registered by the FIA tests, but with different density potential inside the fuel tank.

[rgava]

For a fuel to be used at a race it has to be approved by the FIA.

The FIA run several tests on the fuel to make sure that it is within the rules. They run a gas chromatograph test and create a "fingerprint".

At each race all the teams submit a sample of the fuel they are using to be tested by the FIA. The fuel has to match the "fingerprint" of an approved fuel.

Samples are also taken after qualifying and the race, and these too have to match the approved fuel specification.

I'm not sure this leaves much scope for gaming the fuel flow sensor by changing the fuel's bulk modulus.

The fuel flow sensor is calibrated so that a given output represents a certain mass flow rate. This may also take into account the fuel temperature.

Yes, it does: the bulk modulus reflects the specific space between atoms and molecules of given fuel at given temperature. Of, course, if you find a way to alter this space without changing the temperature, you will have the same fuel with the same chemichal composition registered by the FIA tests, but with different density potential inside the fuel tank.

Can you please explain how you plan to alter the specific space between atoms and molecules without changing the chemical composition, the temperature or the pressure?

[subcritical71]

The fia supplied fuel sensor measures the speed of sound of the fluid. It is not a reference or lookup. It is a measured value. I posted above the manufacturer links which show this in the sensors technical data.

[j.yank]

For a fuel to be used at a race it has to be approved by the FIA.

The FIA run several tests on the fuel to make sure that it is within the rules. They run a gas chromatograph test and create a "fingerprint".

At each race all the teams submit a sample of the fuel they are using to be tested by the FIA. The fuel has to match the "fingerprint" of an approved fuel.

Samples are also taken after qualifying and the race, and these too have to match the approved fuel specification.

I'm not sure this leaves much scope for gaming the fuel flow sensor by changing the fuel's bulk modulus.

The fuel flow sensor is calibrated so that a given output represents a certain mass flow rate. This may also take into account the fuel temperature.

Yes, it does: the bulk modulus reflects the specific space between atoms and molecules of given fuel at given temperature. Of, course, if you find a way to alter this space without changing the temperature, you will have the same fuel with the same chemichal composition registered by the FIA tests, but with different density potential inside the fuel tank.

Can you please explain how you plan to alter the specific space between atoms and molecules without changing the chemical composition, the temperature or the pressure?

If I knew, I would not speak here

[rogazilla]

Remember last weekend Merc was caught cooling their fuel more than allowed?

[63l8qrrfy6]

Changing the modulus of the fuel will not change the density.

In a fluid, the bulk modulus K and the density ρ determine the speed of sound c (pressure waves), according to the Newton-Laplace formula
https://en.wikipedia.org/wiki/Bulk_modulus

Obviously, if you wish to keep the speed of the sound in given medium constant (as reqiired by the F1 regulations regarding the flow sensor), bulk modulus and density are interlinked.

AFAIK the flow sensor is not sensitive to the speed of sound in fact it calculates the speed of sound of the medium.

I think you are spot on.
The FIA sensor is an ultrasonic "transit type" flowmeter which means it does calculate the fluid velocity as well as the speed of sound.

Data sheet below:
https://www.sentronics.com/wp-content/u ... etMSDS.pdf

[Espresso]

Think more basic, Ferrari isn't cheating any sensor. The engine just works with the fuel, to me that is the big difference

Not really up to find it back, but if memory serves me well good old 'Charlie' once mentioned that the FIA is aware of the way Ferrari applied the rules and it was within the regulations and up to the other teams to discover.

That discussion went about Ferrari's advantage and the application of hybrid energy.

Guess the other still don't know how to...
and don't cheat on the fuel flow sensor as everyone is wildy speculating...

[hollus]

Posts from the Ferrari PU thread have been moved here as they were about the sensors in general.
Please continue discussion about the flow sensors specifically and related issues (accumulation in lines?) here.

[henry]

According to a report in AMUS the second sensor will run at a secret frequency and will be randomly allocated. Suggests they are trying to defeat an exploit such as @mudflap suggested.