9. Example of an industrial problem

In this example, a cracking problem was encountered at the attachment of the blades to the ceiling at the impeller outlet and at the attachment of the blades to the belt at the inlet on specific high-speed impellers (figures and ). These cracks were discovered during periodic inspections of the units. Nowadays, problems of this type are rare, since mechanical engineers are able to calculate the static stress field exerted on the impeller blade from the pressure map supplied by the hydraulic engineer. The maximum stresses at the blade outlet on the ceiling side generally lead to an increase in the thickness of the trailing edge of the blade in this area. The price to be paid is one or two tenths of an efficiency deficit.

Faced with such a situation, the manufacturer is obliged to find an explanation and a solution, to ensure the...