| As the core equipment of the cooling system, Circulating water cooling tower fan was widely used in industrial production, with the continuous increase of the fan diameter, reducing the of the pressure head and increase of the volume, circulating water cooling tower fan is inevitably appeared vibration phenomenon in the operation of the wind fan process, which is seriously affects the safe and reliable operation of the fan. This paper analyz vibration reliability problem of circulating water cooling tower fan based on the mechanical vibration theory and the theory of structural reliability.According to the structure characteristics of the circulating water cooling tower fan, the free vibration equations of the fan impeller is established and fan impeller free vibration response and frequency are obtained. Then, considering the uncertain variables influence on fan impeller vibration characteristics, according to modal orthogonal normalization condition, the partial derivative of natural frequency to the uncertain variables are obtained, provide a theoretical basis for solving the vibration reliability model for the fan.Based on the principles that the absolute value of the difference between the natural frequency and excitation frequency of the system should be within a certain range, the reliability function of the system is established, according the distribution function of the system function is unknown, using the maximum entropy principle, the vibration frequency reliability mode with single failure mode based on the second fourth-order moment method can be established. Then integrated the correlation between the various failure models, the vibration frequency reliability model with multiple failure modes of circulating water cooling tower fan is obtained.Considering response random uncertainty information which is existed the vibration response of circulating water cooling tower fan, based on the free vibration differential equation of fan, the dynamic response expression of fan and partial derivative of system response to uncertain variables are obtained simultaneously, considering fuzzy is existed by the transformation from reliable state to the unreliable status in the process of fan, using fuzzy theory,the dynamic response reliability model of circulating water cooling tower fan is constructed and reliability analysis method of the dynamic response of the circulating water cooling tower fan can be determined.Taking the axial flow fan in circulating water cooling tower installation of the compound plant refrigeration station of Nanhua Co.Ltd, in Nanning, Guangxi as the object, based on the calculation and analysis on the vibration reliability of the axial flow fan, the effectiveness of the circulating water cooling tower fan vibration reliability model can be verified. |
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