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Anonymous Poster #1

Flow Rate Possible Fuel vs Air Medium

11/09/2012 4:48 AM

Sir,

Could you tell the way to derive the possible flow of Jet A1 fuel through a valve for same pressure drop (21kPa) when the maximum possible flow of air is 1400 lpm with the pressure drop of 21 kPa after that flow chocking has started which is clear from the steepness of the flow Vs pressure drop curve.

Will my flow rate of Jet A1 fuel will come down or it will increase compared to air?

Because, from the equation of friction loss, friction factor is directly proportional to kinematic viscosity of the fluid which is less for fuel compared to air. So the equation tells, for the same 21kPa, fuel flow rate will increase.
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PWSlack
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#1

Re: flow rate possible Fuel Vs Air medium

11/09/2012 5:11 AM

Please post a sketch.

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lyn
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#2

Re: Flow Rate Possible Fuel vs Air Medium

11/09/2012 7:46 AM

Measure it.
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Anonymous Poster #1
#3

Re: Flow Rate Possible Fuel vs Air Medium

11/09/2012 8:37 AM

Sir,

Sorry, one point i missed is pressure drop is a function of density. from frictional head loss i'l get less head loss for fuel compared to air but when i find the equivalent pressure drop, it will come very high compared to air based on the density ratio.(804/1.18 = (fuel density/air density)). Kinematic viscosity of air is 1.562 x 10^-5, for fuel is 1.5 x 10^-6.

my valve is having a equivalent flow cross section area of 18 mm ID pipe. Please correct me sir.
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Codemaster
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Location: Stoke-on-Trent, UK
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#4
In reply to #3

Re: Flow Rate Possible Fuel vs Air Medium

11/10/2012 10:17 AM

Mainly due to the density difference, for a given pressure drop the velocity (and volume flow) is higher for gas than liquid, by factor √(density ratio) but the mass flow is lower by same factor. At the high Reynolds No. here, the kinematic viscosity makes little difference.

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