I am modelling an existing system based available existing data
https://wetransfer.com/downloads/80e1332b0b7336c2e2c8efa747e8644620191021165352/0d202857ca77e7415e68e38c4c4707cc20191021165352/f55c3c
Tank Inlet pipe flow is zero and many locations pressure less than 1 bar. Moreover, multiple locations velocity exceeds 14 m/s
Please check the model and let me know the possibility of errors also how to mitigate the issues
Hello Raghavendra,
If you observe velocities greater than 3 m/s are in pipes where flow is large i.e. > 1000 m3/h, where diameter ranges from 300 mm or 400 mm. These are trunk mains, due to high velocity and large flow, headloss occurs in these pipes, which also increases head of pumps. If you are increasing diameter of these trunk mains to 500 mm at least then velocity will reduce and so will headloss. E.g. In case of pipe PW-3338, diameter is 150 mm but flow is 891 m3/h, so velocity is 14 m/s as it is carrying large flow causing headloss, in such cases you need to increase the diameter to carry large flow smoothly.
About pressures being less than 1 bar at some junctions, this is happening in low lying areas. Low pressure is seen on upstream sides of tank e.g. at junction P-1535 pressure is 0.05 bars, if you create a profile in this area you will see that HGL goes down as there is no hydraulic boundary element in this area to maintain or raise the HGL so enough pressure is achieved. As HGL goes down pressure also decreases, as difference between HGL and elevation decreases. If you put a PSV here to sustain / maintain pressure then required pressure can be achieved in this area.
About zero flows in tank inlet pipes, if you observe the upstream HGL porfile for tank 3 where inlet pipe is now providing flow you will see that its a flat profile and for tanks where flow is provided there was drop in HGL upto the tank so flow is supplied to tank. I am investing to provide a solution for this, will update you soon.
Regards,
Sushma Choure
Bentley Technical Suppport