The reduction of the noise emission level of hydraulic pumps has been a primary research goal in the fluid power field for decades. To pursue this goal, a significant effort has been put in identifying the sources of noise generation, and formulating proper methods to reduce them. Most common methods include the analysis of the kinematic features of the displacing action realized by the unit, and/or the pressure fluctuation at the pump ports. However, the physical complexity associated with the noise transmission into the pump structure and the surrounding environment has not permitted so far to achieve clear correlations between fluid-borne noise sources and actual emitted noise. Recently, the advancement in numerical acoustic modelling techniques has permitted to explore these features, so that in future, quieter units could be designed with the help from simulation.

This paper contributes in this topic, considering as a particular reference unit, the case of external gear pumps. An acoustic model developed by the authors’ research group permits to perform analysis of both structure- and air-borne noise, by combining a modal analysis performed in ANSYS and an acoustic simulation in LMS.Virtual.Lab. As pressure and force loading inputs, the model utilizes the results of the authors’ HYGESim tool.

To show the model’s potentials, the paper takes into considerations two alternative gear designs suitable for the same pump casing: one single flank and one dual flank (zero-backlash). The dual-flank design is commonly considered as a quieter solution for spur gear pumps. These designs are properly selected to show differences in fluid-borne noise source, and describes the features of the noise transmission as predicted by the model. By showing the simulated level of airborne noise for the two considered designs, the results of this paper confirm the advantages of the dual-flank solution, and point out how the proposed model can be used in future for virtual design purposes.

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