| Centrifugal blower is a kind of important general equipment to provide airflow power in industrial production. Currently, the Centrifugal blower can be divided into three types: roots blower, low-speed multistage centrifugal blower and single-stage high-speed centrifugal blower, and the last one with the couplings, gear overdrive system has the highest efficiency. Air suspension single-stage high speed centrifugal blower takes the high-speed motor to drive the impeller directly, without coupling and gearing-up, so the transmission loss caused only by the gas viscous friction. Compared with the traditional single-stage blower, air suspension direct-drive single-stage blower is undoubtedly more in line with current development trend advocating low-carbon energy and green living in China.In view of the air suspension direct-drive high-speed centrifugal blower has significant economic value, the author aiming at the key technology of this type of blower does a certain research in this paper, and the system consisting of impellers, gas bearings and the permanent magnet rotor is undoubtedly the key of the research. First of all, according to performance requirements of the blower, the author makes a selection about the PMSM and completes the overall architectural design of the blower in full consideration of the conditions which keeps the motor effective cooling in the air. Besides, the author also determines the types of bearings and the form of suspension rotor supported by gas bearings. Secondly, the model of centrifugal blower that could satisfy the specific requirements is established via one-dimensional thermal design theory and the CFturbo software. The author also makes a three-dimensional flow field analysis via the Fluent software, and uses the numerical Analysis results to check the relevant design specifications and determine the parameters of the labyrinth seal. Thirdly, based on the method combining Newton iteration and central difference discrete, the author establishes the mathematical model used to research the static characteristics of foil journal bearing and rigid surface thrust bearing and studies the relationship between structure parameters and the static characteristics of bearing by MATLAB. What’s more, the author completes the parametric design of bearings for the system in this paper with specific load requirements. Besides, based on the basic idea of a small perturbation, the author establishes the mathematical model for calculating dynamic coefficient of foil journal bearings, and solves the supporting stiffness and damping of the foil bearings at the same frequency of vortex under the condition of a specific load by MATLAB programming. Finally, based on FEM and Timoshenko beam theory, the author sets up the equation of motion of the system consisting of impellers, bearings and the permanent magnetic rotor. Then the author studies the critical speed of system in each state and vibration mode by writing a MATLAB program. The unbalance response of the system are also analyzed via the method of Newmark-beta. |
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