Hi, Urgent ! need help I'm working on a centrifugal pump, the goal is to evaluate the performance curve of the pump (i.e head vs flow rate) now, i started by using a Total pressure inlet (0 atm) and a mass flow outlet and by changing the desired outflow i would just simply calculate the delta p based on that flow rate and deduce the elevation ..however, i was told that i need to do the opposite thing, meaning that i have to impose a head value and then evaluate the out flow as a result . the problem is I can't find a way to impose that condition, let's say that i need to find out the flow rate of the pump at a total head = 30 m ..how can use that 30 m to determine the pressure needed at the outlet since i have no information about the flow velocity any suggestions please ?? Thank you
You need to know the pipe resistance from the pump discharge to the final point where you send the liquid.
With this pipe resistance, calculate the friction pressure drop for each flow rate.
The friction pressure drop + the differential height between the pump discharge and the final point + the velocity head, is the required discharge pressure of the pump.
Emilio Casado thank for replying
Let's assume that there is no losses due to friction, imagine the case where the pump is directly pumping into the air from its outlet ..since the head is the delta P (by P i mean total pressure) divided by (density*g) so we'll have Total pressure at outlet = total pressure at inlet + head*density*g and since Total pressure at outlet = static pressure + 0.5*density*velocity^2 Will this mean that at the outlet i should have a static pressure outlet of a value = Total pressure at inlet +head*density*g - 0.5*density*velocity^2 ??
If the friction pressure drop and the static head are 0, the centrifugal pump goes to run-out because the head of the pump decreases, following its curve, the flow rate and the required power increase and the electric motor of the pump, burns out.
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