Analytical models have been developed that can be used to investigate the vibration modes that exist in small air-conditioning units and to obtain a clearer understanding of the influence of gyroscopic effects on these vibration modes. Techniques have been developed that can be used to determine the values of the mass and stiffness coefficients in the analytical models from measured data. The analytical model that incorporated the effects of the gyroscopic moment associated with the fan impeller indicated the gyroscopic moment resulted in forward and backward fan impeller whirling modes. These modes were associated with each of the rocking and swaying vibration modes that existed in the two air-conditioning units examined during this project. The correlation between the measured and calculated system resonance frequencies associated with specific vibration modes was very good.

Units: SI