Hydraulic turbines - Tests - Cavitation

In this article, we will only examine the hydraulic aspects of turbomachinery operation. Other aspects concerning mechanics or control have already been covered in some articles in the [B 4 405] collection, for example, cf. [Doc. BM 4 406v2] . The three-dimensional, unsteady and viscous nature of the flow cannot be tackled by calculation alone. Numerous scale-model tests are required to gain a better understanding of the hydraulic phenomena at play in the prototype machine. We will review the following points in turn:

• calculating the efficiency and power output of the impeller ;

• study of the cavitation behaviour of impeller blades ;

• predicting flow instabilities in industrial machinery.

An example of cracking encountered on a wheel of a low-head power plant will show that industrial problems are still with us.