How to calculate the flow velocity and flow rate of water flowing by gravity in a tank
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There is a water tank located on a floor 15 meters high; the tank itself is 2 meters tall. An outlet at the bottom of the tank is connected to a DN25 seamless steel pipe, through which water flows by gravity to the bottom of the first floor. How can the flow velocity and flow rate of the water in this pipe be calculated? The vertical height is considered to be 15 meters
This post was last edited by pump-fans on 2021-12-3 07:55. Flow rate is flow divided by cross-sectional area; the key factor is the flow rate. Since the site conditions are uncertain, refer to the hydraulic calculations for short pipes in \"Fluid Mechanics and Turbine Theory\" and carry out rough calculations on your own
This post was last edited by 3983596_FPPZ on 2021-12-3 at 08:37. You have relatively few parameters specified; at the outlet of the pipe at the bottom, 15 meters of potential energy is converted into kinetic energy (flow velocity) after accounting for losses. The challenge lies in calculating exactly how much loss there is, as well as considering the roughness of the pipe walls. Since the pipe is too thin, it is highly affected by various factors, making it difficult to estimate accurately. You can conduct the following experiment: the pressure of tap water is roughly around 10 meters of head pressure. Connect a pipe with a diameter of 25 mm to test the flow rate or velocity; I estimate that the flow velocity will be around 5-8 m/s. Based on the pipe diameter, the flow rate would be approximately 10-15 m3/h. This issue relates to the calculation of frictional losses and local losses. There are countless questions online asking about the head that a pump can generate and how far it can deliver fluid; these questions are essentially the same as yours, as they all concern the calculation of frictional losses and local losses. The Bernoulli equation is essential for this purpose. I hope this helps you