Fire dynamic simulator : Fuel density regarding

pv_cfd · September 7, 2021, 02:11

hi all,
I am working on fires at different altitudes (reduced air pressures) and using Pyrosim interface. Used volume flow rate (area*vel) to specify the rate of flow.
I am using methane as fuel and the density of the fuel will also be less at higher altitudes.

My doubt is whether I need to use a mass flow rate inlet and reduced mass flow rate to accommodate the variation in density of fuel with altitude.

I have set the simulation parameters- reduced pressure and reduced oxygen fraction already.

Will FDS take this fuel density variation automatically if I specify a volumetric flow inlet?

beckham86 · October 1, 2024, 05:35

When simulating fires at different altitudes using Pyrosim, it's crucial to consider the variation in fuel density. While specifying a Among Us volumetric flow inlet, FDS does not automatically adjust for changes in fuel density due to altitude. Therefore, using a mass flow rate inlet with the reduced mass flow rate is advisable to accurately reflect the lower density of methane at higher altitudes.

September 7, 2021, 02:11	Fire dynamic simulator : Fuel density regarding	#1
pv_cfd New Member praveen Join Date: Sep 2021 Posts: 1 Rep Power: 0	hi all, I am working on fires at different altitudes (reduced air pressures) and using Pyrosim interface. Used volume flow rate (area*vel) to specify the rate of flow. I am using methane as fuel and the density of the fuel will also be less at higher altitudes. My doubt is whether I need to use a mass flow rate inlet and reduced mass flow rate to accommodate the variation in density of fuel with altitude. I have set the simulation parameters- reduced pressure and reduced oxygen fraction already. Will FDS take this fuel density variation automatically if I specify a volumetric flow inlet?

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October 1, 2024, 05:35		#2
beckham86 New Member beckham Join Date: Oct 2024 Posts: 6 Rep Power: 2	When simulating fires at different altitudes using Pyrosim, it's crucial to consider the variation in fuel density. While specifying a Among Us volumetric flow inlet, FDS does not automatically adjust for changes in fuel density due to altitude. Therefore, using a mass flow rate inlet with the reduced mass flow rate is advisable to accurately reflect the lower density of methane at higher altitudes.