Lumped parameter models of crescent pumps (2015-2016)

A 0D model for internal gear (crescent) pumps has been developed and validated. The approach is based on the identification of three variable control volumes regardless of the number of gear teeth. The evaluation of the volume derivatives is grounded on the knowledge of the length of the vector rays between the centres of the gears and the contact points. The model has been implemented in the commercial environment Simcenter Amesim with the development of customized components. Specific attention has been paid to the leakage passageways, some of them affected by the deformation of the cover plate under the action of the delivery pressure.

The definition of the control volumes is reported in figure 1, where the trapped volume is defined only when two contact points exist.

Figure 1

The complete 0D model, relief valve included, is shown in figure 2, where Vd, Vs, and Vt represent the delivery, suction and trapped volumes respectively.

Figure 2

The delivery pressure, normalized with respect to the mean value, is plotted in figure 3. The measurement was performed with a simple geometry of the test circuit, made up of a straight rigid pipe.

Figure 3

More analyses and details are available in:

RUNDO M, 2017: Theoretical flow rate in crescent pumps

RUNDO M, CORVAGLIA A, 2016: Lumped Parameters Model of a Crescent Pump

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• MASSIMO RUNDO