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Compressible choked gas flow through an orifice -- Excel formula
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[QUOTE="FluidDroog, post: 6615279, member: 699955"] Hi Stuart, Let's get to the bottom of this. Perhaps a unit conversion problem here. At a P of 301 Bar (30.1 MPaA), rho = 46.01 kg/m^3, engineering toolbox has a good write up on this [1]. Using the correct density values in your spreadsheet, I compare the sonic output to Lenox Laser's orifice calculator [2]. To do so, I need to convert mass flow and 'standard' liters/min from [3]. standard Liter/min = mdot * 60e3 * 22.414/MW * 1000 With P0 = 200 barA and T=0 C input into both sonic calculators the outputs are within 20% of each other. This validates your sonic formulas, the primary issue is the density calculation (check your units). Why the 20% difference? I estimate the ideal Cd to be 0.72 following equation 2 from [4] which is about 20% different from 0.6. [B]References:[/B] [1] Helium gas Density [URL]https://www.engineeringtoolbox.com/helium-density-specific-weight-temperature-pressure-d_2090.html?msclkid=5aa74f92ae2d11ec8afe2093b604c2d8[/URL] [2] Lenox Laser Orifice Calculator [URL]https://lenoxlaser.com/resources/calculators/orifice-calculator/?msclkid=69c42910ae2011ec82ce61f227854fdd[/URL] [3] Converting mass flow to sccm [URL]https://www.physicsforums.com/threads/convert-mg-s-to-sccm-standard-cubic-centimeters-per-minute.917608/post-6614235[/URL] [4] NIST. Comparison of CFV Theoretical Models to Experimental [URL]https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=830961&msclkid=3570c7ddae2711ecba4468e745bee897[/URL] [/QUOTE]
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Thermodynamics
Compressible choked gas flow through an orifice -- Excel formula
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