I would like to ask everyone for advice on calculating the flow velocity at the pipe outlet
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Gentle experts, I’m a newcomer. I have a current engineering calculation problem for which I seek advice. What is the general idea? If a pump with a rated head of 50 M and a flow rate of 40 cubic meters per hour is installed, using pipes with a diameter of DN50 over a length of 100 meters, how should the exit flow velocity be calculated assuming no pipe losses? I think the Bernoulli equation should be used for the calculation: P1 + pV^2/2 = P2 + pV^2/2. Once the flow velocity is determined, the flow rate can be found using Q = V * S. But I don’t know what the pressure is at a pipeline length of 100 meters. How should this be calculated?
My calculations are as follows: since the outlet is directly connected to atmospheric pressure, the outlet pressure is 0.1*10^6 Pa. According to Bernoulli’s equation: 0.5*10^6 + 1*10^3*V1^2/2 = 0.1*10^6 + 1*10^3*V2^2/2. Here, V1 = Q/S = 40/3.14*(0.05/2)^2/3600 = 5.5 M/S. Substituting this value into the equation gives V2 = 28.8 M/S. This seems like a relatively high flow velocity.
Is there any senior who can give some advice?
With flow rate and pipe diameter, the velocity can be calculated by using the volume flow rate. For a DN50 pipe, the inner diameter is approximately 50 millimeters; the cross-sectional area of the pipe is 1.96*10^(-3) square meters. The flow rate is 40 cubic meters per hour, which is equivalent to 0.011 cubic meters per second, and the flow velocity in the pipe is 5.6 meters per second. If there is no pipe loss, the pressure 100 meters later is the same as the outlet pressure.
Thank you. Is the Bernoulli equation applicable in this case?
Furthermore, in this case, if the pipe opening is directly connected to the atmosphere, what are the exit flow velocity and pressure?