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abudaniell May 16, 2008 09:52

discharge coefficient

May somebody explain to me how to obtain the discharge coefficient for orifice meter after we run the simulation for flow through orifice in pipe. Basically from the simulation result we just get the pressure different between upstream and downstream of orifice. How to use this data to get the discharge coefficient.

Thank you

Thiru May 16, 2008 10:21

Re: discharge coefficient
Hallo for determing discharge coefficient, please check Unit Operations of Chem Engg by MCCabe & Smith. chapter 8. Transportation and metering of Fluids.

Formula : U = (C/sqrt(1-B^4)) * sqrt (2 * (Pa-Pb)/rho) U is velocity through orifice. B is ratio of orifice diam to pipe diam rho is density of the fluid

Re = (D*U*rho/mu) = 4*Mf/(pi*D*mu) will be useful to get the Velocity at the Orifice

Mf is mass flow rate mu viscosity.

abudaniell May 24, 2008 21:43

Re: discharge coefficient
Thank you. I have got the equation. I do a simulation of flow through orifice, with D - D/2 pressure tapping with using 2 dimensional model: 1. Which the pressure that should be used in the equation. Pressure at the wall? Pressure at the center of pipe? 2. Since I running using 2D model, when I check the result in summary it showed that the area of orifice is same with diameter that I set. So to obtain the mass flow rate it is using area as pi*D^2/4 or just using the value of diameter (D).

rajendrrks April 21, 2013 08:31

cd v/s Re plot
hell guys , me and my friends are doing non-newtonian fluid flow through orifice ...and at d result we have to analyse changes in cd with respect to reynold d moment wat problems we are facing is we dont know how to plot co-efficient of discharge against reynold's number...can anybody tell us how to plot cd v/s Re waiting for ur reply ..thanku ..:)

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