“…The optimized function is usually the 40 " Total pressure Mass flow rate RANS, Frozen rotor k-e, k-x SST Zhang et al 41 " Total pressure Velocity RANS, k-x, SST Nejad et al 6 " Total pressure Mass flow rate CFX, RANS frozen rotor, k-e, k-x SST Fathi et al 43 " Mass flow rate Pressure outlet Reynolds Stress Model Jeon et al 18 " Atmospheric pressure Mass flow rate No slip CFX, RANS, SST Pei et al 44 " " Velocity obtained from experiments CFX RANS, SST, k-x Zhang et al 45 " " " 3D, unsteady, SST, k-x efficiency or the discharge pressure. The parameters varied are the impeller size, 16,23,33,38,51 blade inlet and exit angles 6,19,23,32,39-42,46,52,55 that ranged from 0 � to 90 � : blade shape 6,9,17-19,31,39,47 varied among radial, forward swept, backward swept, twisted, symmetric, asymmetric, chevron as well as S-Shaped blade thickness, 18,35 rotational speed 6,16,20,26,[31][32][33]38,43,47,55 varied from 1450 to 25,000 rpm and stripper angle 20,29,44 varied from 270 to 344 � . No optimization study used any of the established engineering optimization techniques.…”