Four quadrant pump curves

The pump characteristic curve defined on the Pump Curve Page for a pump object is appropriate for normal pump operation (discharge and head both positive), but not for pump operation outside of the normal zone.

During a transient event, turbining, flow reversal, speed reversal, etc. may occur. All combinations of positive and negative discharge and head should be considered.

InfoWorks TS includes eight built-in four quadrant characteristic pump curves describing pump behaviour during normal and abnormal pump operation. Three of the curves have been constructed using data from Hollander's experiments on centrifugal pumps tabulated in Wylie and Streeter (1983, 1993). An additional five have been constructed using data provided by Thorley (1991).

An example curve is shown below. Curves of h/(a2+v2) and b/(a2+v2) are plotted, where:

h = H/HR = Actual Head / Rated Head

v = Q/QR = Actual Flow / Rated Flow

a = N/NR = Actual Speed / Rated Speed

b = T/TR = Actual Torque / Rated Torque

The curves are plotted over a range of 0 to 2p using 89 data points at intervals of p/44 radians.

Four Quadrant Curve Example

 

Quadrant	Zone	Flow (v)	Speed (a)	Head (h)	Torque (w)	Definition
I	A	+	+	+	+	Normal pumping
I	B	+	+	-	+	Energy dissipation
I	C	+	+	-	-	Reverse turbine
II	D	+	-	-	-	Energy dissipation
II, III	E	±	-	±	-	Reverse rotation pumping
III	F	-	-	+	-	Energy dissipation
III	G	-	-	+	+	Normal turbine
IV	H	-	+	+	+	Energy dissipation

Table 1: Pump Operating Zones and Quadrants

 

The pump file to be used is determined based on the quantity of specific speed. The file associated with the specific speed closest to the calculated speed value is selected.

Specific speed is calculated as:

(1) where: NR = Rated Speed, rpm QR = Rated flow, m3/s (gpm) HR = Rated head, m (ft)

 

Pump File	Pump Specific Speed (SI Units)	Pump Specific Speed (US Units)
1	25	1270
2	147	7600
3	261	13500
4	72	3725
5	85	4409
6	101	5203
7	131	6792
8	169	8764

Table 2: Built-in Four Quadrant Files