This paper describes research involving an in-service failure of a ââ?¬Å?variable pitch in motionââ?¬Â fanââ?¬â?¢s blade bearing. Variable pitch in\r\nmotion fans rotate at a constant speed, with the changing blade angle varying the load. A pitch-change mechanism facilitates the\r\nchange in blade angle. A blade bearing supports each blade enabling it to rotate. The author observed that as the fan aerodynamic\r\nstage loading progressively increased, so did the rate of blade-bearing wear. The reported research addressed two separate, but\r\nlinked, needs. First, the ongoing need to increase fan pressure development capability required an increase in fan loading.\r\nThis increase was within the context of an erosive operating regime which systematically reduced fan pressure development\r\ncapability. The second need was to identify the root cause of blade-bearing failures. The author addressed the linked needs using\r\na computational analysis, improving the rotor inflow aerodynamic characteristics through an analysis of the inlet box and design\r\nof inlet guide vanes to control flow nonuniformities at the fan inlet. The results of the improvement facilitated both an increase in\r\nfan-pressure-developing capability and identification of the root cause of the blade-bearing failures.
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