High Speed Rotating Fan

The Problem

Problems related to the distortion of a high speed rotating fan were reported by our client and the issue was attributed to the design of the unit, in particular the existence of stress raisers and the possibility of exceeding the tensile stress of the material at high speeds of 7500 rpm. Thus an FE analysis was carried out to identify this possibility and areas for improvement.

The Approach

A linear analysis with rotating centrifugal sources was carried out with I-DEAS. Several configurations and rotating speeds were used to produce a performance graph. A new design was then identified and the same process carried out in order to compare and contrast the new concept.

The Result

The FE analysis indicated that there was a strong possibility that the original design could exceed the tensile strength of the material at speeds of 7500 rpm. A prompt redesign which involved increasing geometrical thickness, the addition of appropriate radii and a redesign of the base of the fan blade allowed these higher speeds to be reached with the bonus of an additional safety allowance of approximately 50%. The redesign was put into practice and has performed faultlessly since installation.