Methodology for system-level analysis of a fan–motor design for a vacuum cleaner

In the present study, a methodology for conducting a system-level analysis of a fan–motor assembly in a vacuum cleaner is presented. This system consisted of three components, a fan, motor, and the flow resistance of the motor, or of the vacuum cleaner. The combined characteristics of the fan and the motor were obtained from torque matching at a constant throttling condition, and a pressure drop was implemented under a constant flow rate to account for the flow resistance. By combining these two steps, the performance characteristics of the fan–motor assembly and the vacuum cleaner system could be predicted over the whole range of operation, based on the characteristics of each component. The predicted performance for power, flow rate, pressure, and efficiency using the present method agreed well with the experimental results obtained for an equivalent system, within 2% difference at best efficiency point. Three models of the fan–motor assembly (S1, S2, and S3) were analyzed at the component level, and the decrease in efficiency produced by flow resistance was estimated to be 1% (S1 and S3 models) or 4.7% (S2 model) using the present method. The characteristics of the fan, extracted from those of the fan–motor assembly, were used for validating the computational fluid dynamics. The computational fluid dynamics results of this study predicted higher efficiency due to simplification of the geometry, but an accurate prediction of best efficiency point location was obtained. The proposed method is also applicable for detecting system leakage and identifying system resistance without direct measurement.