Figure 4. The figure on the left shows an increasing weight loss (due to increasing erosion) with an increasing height difference between the stationary and the rotating part of the turbine. The figure on the right shows how there is a correlation between the width of the tracks and the number of rotations. Increasing the number of rotations will significantly increase erosion by increasing the track width.
Based on the results of the experiments carried out, the general erosion model has become more specific, so that it becomes more accurate for the operation of Francisturbiner in water with sediments. The "new" model also includes the width and height differences between the rotating and the stationary part of the turbine.
It is quite obvious that the presence of sidewall gaps and flow in such regions is difficult to get around in hydraulic machineries. The design process should therefor ensure sidewall gaps flow as well for efficient machine design. Flow phenomenon associated with sidewall gaps should be well considered and analyze them during the beginning phase of machine design.