Air Flow Calculation for Orifices: Diameter and Length Requirements

[irisaa]

Hallo,
How to calculate the air flow (volume flow in m³/s) through an orifice of diameter ∅ 1mm, 1.2 mm and 1.5 and length 1mm? The air at room temperature is sampled through the orifice from atmosphere at pressure 1013 mbar. The pressure behind the orifice is regulated at 100 mbar or 200 mbar.
Thank you for your help

 

[P90rippin]

Hi, there's a nice free program that will help you calculate the flow rate. Google "Daniel orifice flow calculator". You'll need an internal pipe size to complete the calculation.

 

[irisaa]

Thank you but thus program works for pipe only with inner and outer diameter included as beta coefficient.
My question concerns only nozzle (orifice) of ∅ 1mm, 1.2 mm and 1.5 mm with no outer diameter.

 

[Romel]

You can use the Bernoulli's energy equation to solve for the flow noting that it is constant.

 

[alphy]

.

Hello,

To calculate the air flow through an orifice, we can use the Bernoulli's equation, which relates the pressure, velocity, and height of a fluid in a closed system. In this case, the air is considered a fluid.

First, we need to convert the units to the International System of Units (SI). The pressure in mbar can be converted to Pascals (Pa) by multiplying by 100. The diameter and length should be in meters (m).

Using the Bernoulli's equation, we can calculate the velocity of the air at the orifice:

V = √(2ΔP/ρ)

Where V is the velocity, ΔP is the pressure difference (1013 - 100 = 913 Pa or 1013 - 200 = 813 Pa), and ρ is the density of air at room temperature (1.225 kg/m3).

Next, we can calculate the volume flow rate using the formula:

Q = AV

Where Q is the volume flow rate, A is the cross-sectional area of the orifice (πr2, where r is the radius of the orifice), and V is the velocity calculated in the previous step.

For an orifice with a diameter of 1mm and length of 1mm, the radius would be 0.0005m and the cross-sectional area would be 7.854 x 10^-7 m2. Plugging in the values, we get a volume flow rate of 2.47 x 10^-7 m3/s for a pressure difference of 913 Pa and 2.64 x 10^-7 m3/s for a pressure difference of 813 Pa.

For an orifice with a diameter of 1.2mm and length of 1mm, the radius would be 0.0006m and the cross-sectional area would be 1.131 x 10^-6 m2. Plugging in the values, we get a volume flow rate of 3.12 x 10^-7 m3/s for a pressure difference of 913 Pa and 3.34 x 10^-7 m3/s for a pressure difference of 813 Pa.

For an orifice with a diameter of 1.5mm and length of 1mm, the radius would be 0.00075m and the cross-sectional area would be 1.767 x 10^-6 m