Numerical Analysis on Pressure Fluctuation of an Axial Flow Fan with Abnormal Installation Angles of a Single Blade

Taking the OB-84 variable-pitch axial-flow fan as an object of study, an unsteady calculation was conducted on the internal dynamics and fan performance under different deviation degrees of a single blade, so as to obtain the time-domain and time-frequency characteristics, and the distribution of time-averaged static pressure and equivalent stress. Simulation results show that both the pressure signal and pressure fluctuation energy at each monitoring point exhibit unusual features with abnormal installation angles of blade, especially the most obvious changes at impeller outlet. The impacts of abnormal blade installation on time-domain and time-frequency characteristics are enhanced with rising deviation degrees, resulting in increased intensity of pressure fluctuations. The approximate entropy at each monitoring point changes obviously with large deviation degrees, indicating good characterization ability on the abnormal blade installation. Remarkable changes are found in the distribution and values of time-averaged static pressure, but the equivalent stress only varies obviously in values.