The goal of this case is to optimize the shape of the propeller, but at the same time reduce the impact of manufacturing variability on the performances. This is of particular importance for marine applications, where even small performance drops during operation can have significant financial impact through increased operational costs. A standard (deterministic) optimization is compared with a robust optimization, taking these manufacturing uncertainties into account.
Both optimization studies, deterministic and robust lead to a performance increase of 8.5% in mean efficiency. The important difference is that the deterministic optimization increases the standard variation of the efficiency (thus the variability of the efficiency) by 2.6%. The resulting design is more sensitive to manufacturing influence on the propeller shape.
The robust design optimization, on the other hand, reduces the standard deviation of the efficiency by 17.7%. The resulting blade shapes vary significantly between the standard and robust optimal shapes. This underlines the importance of robust design optimization.
In addition, uncertainty quantification studies of the propeller, allow to better understand the system behavior and to identify the most influential parameters by means of scaled sensitivity derivatives.