Vibration of Standard Pitched Blade Impellers in Baffled Mixing Vessels

This paper presents an experimental investigation of the vibration of standard 45° pitched-blade impellers (PBI) in a baffled mixing vessel. Test conditions include different blade configurations, impeller sizes and rotational speeds. Experiments were conducted in mixtures of water and glycerol, with and without baffles. Three different impellers were used: two, 4-blade PBI with diameter to tank diameter ratios of D/T = 1/2 and D/T = 5/7 and a 6 blade PBI with D/T = 5/7. Impeller orbits were measured directly using high speed imaging and from shaft root strain measurements. The results indicated that the baffles had a strong effect on the vibration characteristics for small tip clearances but less so at large tip clearances.