EXTERNAL GEAR PUMP NOISE FIELD PREDICTION BY HARMONIC RESPONSE AND VIBROACOUSTIC ANALYSES

Since several decades external gear pumps have been employed for energy transmission in hydraulic and fluid power systems. Although they are simple enough to build up, their design requires the analysis of the complex dynamics of the gear tooth meshing process and the consequent fluid pressure distribution. Noise field parameters depend on the pump fluid dynamic phenomena in a very complex way. For this reason, also an approximate knowledge of these parameters has to be seen as a challenging target. This paper refers to the employment of the harmonic response methods and vibroacoustic analyses in order to compute and predict the acoustic field emitted by an external gear pump. The methodology here presented analyzes the noise field emitted by a 8.5 cc/rev external gear pump, considering it as a blackbox. In this respect, the pump finite element model was developed with fixed support between the flange and the workbench. At first the FFT acceleration spectra were acquired in a few points of the pump surface during a shaft speed variation. Then the comparison between numerical and experimental modal frequencies was used in order to improve the pump FE model. Subsequently the vibration spectra measured at some pump surface positions were used as external excitation boundary conditions to the vibro-acoustic model and to assess the sound pressure field emitted by the gear pump in defined positions. The preliminary results showed the potentiality of such an approach as a good compromise between noise prediction accuracy and complexity of the experimental and modelling requirements.