Wing-shape Optimization - Multi-point Optimization

Multi-point Optimization

Still, all of these methods have a weakness – they are tuned for one particular set of conditions and speed. In 2007, Jameson introduced both an additional step and a new method of calculations. To account for additional conditions, such as take-off, landing, climbing, and cruising, the modeler calculates all of these simultaneously, rather than only one at a time. Each gradient calculation g is assigned a weight β. Higher priority items, such as cruising drag, are given more weight. The gradient to determine an overall ‘loss’ or a ‘gain’ for the design is created by summing all the gradients times each respective weight. What this allows for is if a change drastically improves takeoff performance but results in a slight hit on cruising performance, the cruising hit can override the takeoff gain due to weighting. Setting the simulation up in this manner can significantly improve the designs produced by the software. This version of the modeler, however, adds yet another complexity to the initial conditions, and a slight error on the designer’s behalf can have a significantly larger effect on the resulting design. The calculation efficiency improvement takes advantage of the multiple variables. This time, two different points were used for the Boeing 747-200 – Mach 0.85 and 0.87. Unfortunately, optimizing for the two points resulted in less than a 3% improvement over drag and almost no weight improvement on the base design. To check his work, he used the same simulation on another aircraft wing and received similar results. The problem observed is that changes that boosted one point of interest directly conflicted with the other, and the resulting compromise severely hampers the improvement gained. His current research involves a better way to resolve the differences and achieve an improvement similar to the single-point optimizations.