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I have a basic question regarding the calculation of mass flow rates of a channel with multiple outlets. In the scenario depicted in the image below, we have a single inlet with a mass flow rate (m1) of 0.87 kg/s, and I'm trying to determine the mass flow rate (m2) at each of the six outlets.enter image description here

Considering mass conservation,M1 = M2.

                M1          = density * area of all the outlets * velocity
                0.87 (kg/s) = 1.18 * 10^-9 (kg/mm^3) * 6 * 1 (mm^2) * velocity
                velocity    = 122881355.932 (mm/s)
                velocity    = 122,881.355 (m/s)

Now, to find the velocity for one outlet, I divide the total velocity by the number of outlets:

Velocity per Outlet = 122, 881.355 / 6 =  20,480.22 m/s

Therefore, the mass flow rate M2 for one outlet is calculated as:

m2 = 1.18 (kg/m^3)∗ 1 * 10^-6 (m^2) ∗ 20,480.22 m/s = 0.0241666 kg/s

Is this calculation correct?

Thanks in advance.

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2 Answers 2

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No. M1=6 * M2, so the correct mass flow rate at one outlet is 0.87kg/s / 6 = 0.145 kg/s

The way you choose is roundabout but should be correct - I don't know where your mistake is.

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In theory, 1 outlet will have 1/6 of the total mass flow, BUT flow effects will change that.

If you need to have a precise measurement at each exit then calibrated orifices or pitot tubes may be needed.

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