Fan blade resonances
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This document summarizes a finite element analysis of a 10-blade plastic fan design for JK Locowitz Aero Ltd. The analysis found the first resonance mode of the fan blades at 672.99 Hz, corresponding to a fan speed of around 42,000 RPM, well above the target design speed of 7,000 RPM. While there is a very low risk of resonance at the target speed, the document recommends initial prototypes be tested up to 10,000 RPM to establish a safety margin.
Fan blade resonances
- 1. Fan Blade resonances 10/21/17 rev A Don Blanchet 3B Associates dwb3298@verizon.net Prepared for: JK Locowitz Aero Ltd.
- 2. Solidworks model 10 Blades 4.5 inch dia PVC plastic
- 3. FEA mesh 10 node tetras 210,000 Degrees of freedom
- 4. Resonance results , hz Blade fluttering
- 10. Fan speed summary Vibration mode Frequency hz Fan Speed RPM 1 672.99 ~ 42,000 2 700.99 3 701.15 4 701.43 5 701.58 Target design Speed 7,000 RPM
- 11. Conclusions There is a very low risk of fan blade flutter and resonance produced stresses in this design at 7,000 RPM. The first prototypes should be tested to 10,000 RPM to establish margin.