“…This was not the case on the aerodynamics front due to the lack of efficient and accurate modelling techniques (Celi, 1999;Ganguli, 2004) although some progress was also made (Ganguli, 2004). Nevertheless, several authors (Celi, 1999;Walsh, 1991;Le Pape and Beaumier, 2005;Imiela, 2009;Glaz et al, 2008Glaz et al, , 2009Tatossian et al, 2008;Allen et al, 2010) have attempted to devise a variety of optimisation techniques. However, these methods were limited either by their efficiency or the accuracy of the results; reason being that high-fidelity computational fluid dynamics (CFD) simulations are necessary to accurately capture the effects of design changes, especially for rotor aerodynamics and a number of CFD solutions are required for the process with each calculation taking substantial computational time.…”