Centrifugal pump head problem

The flow rate of fluid in the three sections of pipe is the same, but the flow rate is also different due to the blocked pipe diameter. Different Reynolds numbers correspond to different drag coefficients, when Re

In my humble opinion, pipeline resistance calculation is divided into resistance calculation for straight pipe sections and local resistance calculation. And according to the different Reynolds number, the flow pattern of the fluid is divided into laminar flow and turbulent flow. As mentioned above, different flow patterns correspond to different friction coefficients. For laminar flow, the friction coefficient = 64/re. For turbulent flow, you can check the chemical engineering principles book.: The numerical value can be found in the graph of the relationship between friction coefficient and Reynolds number. Calculating the resistance must be done in sections, because the pipe diameters are different and the corresponding flow rates are also different. As for the local resistance, it can be roughly calculated based on 20% of the resistance of the straight pipe, and there is no need to be so detailed.

I have thought very carefully, but I have a small suggestion for you. Basically, the pressure difference is limited through elbows, control valves and other components (or horizontal straight pipes). If you want to think briefly, just consider the vertical height. In other words, look at the height of D+S, which means that the minimum lift of the pump is higher by a certain amount. Basically, if your pump hopes that the lift is D+S=90M, then the minimum lift must be greater than 90... The desired outlet pressure of the pump is the head divided by 10