Automatic Optimization Process
TURBOdesign1 has a script version that can be easily coupled with any automatic optimiser. The most important design parameters such as blade loading can be controlled by simple text files such as .pcf file. In addition, TURBOdesign1 output files can be used to evaluate both aerodynamic and geometrical parameters directly by the optimiser. The design process with TURBOdesign1 being very fast, thousands of designs can be carried out overnight, allowing even optimisations with more than 20 input variables. The optimisation target is to minimise the deviation of the mid surface from the desired 2D blade subject to constraints on the diffusion ratios below a critical value to avoid flow separation.
The main design parameters are the blade loading distribution in stream wise direction on different span-wise positions. However, the meridional channel, the thickness distribution and the main specifications such as impeller speed, blade number and volume flow rate remained fixed during the optimisation.
The original design was a 3D blade designed with TURBOdesign1 (Fig. 1), which already showed very good performance and had an excellent efficiency, but was difficult and expensive to manufacture. The geometrically optimised blade (Fig. 2) has almost the same aerodynamic values as the original 3D blade (Fig. 3) and can be manufactured cost-effectively.
The resulting optimised 2D blade addresses very well the manufacturing constraints and shows the same excellent values for performance and efficiency as the original 3D blade. Manufacturing constraints are only one of numerous possible design targets that can be accomplished by coupling TURBOdesign1 with an automatic optimiser, since this method can be used almost universally.