Stress on stirrer heads

The fluctuating hydraulic forces, which operate on stirrer heads [273], are expressed as Newton numbers Ncf = F/ pn d ) with the forces F operating on the stirrer sur- 

In the sub-critical range the Ncf., values are in general higher than in the supercritical range for propeller and MIG stirrers they are more than double as high as the corresponding Nsf values. The design of the stirrer shaft (same or stepwise downwards tapered shaft diameter) has hardly any influence on the two Ne( values. 

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