Optimizing the Aerodynamic Efficiency of an Aircraft Nacelle
The nacelle is the cover or housing that holds engines, equipment, or fuel on an aircraft. Its design is crucial to the overall aerodynamic efficiency of the aircraft as it often holds key components such as the engine that cannot themselves be easily optimized for aerodynamic efficiency. Given the components the nacelle may house, certain properties, such as the air mass flow intake needed for the engine, needs to be maintained, while reducing the overall drag to increase aerodynamic efficiency.
Complex CFD models often take weeks to create, making optimization time-consuming and often times impractical. The challenge was to find the optimal aerodynamic design while substantially reducing the costs associated with traditional CFD modeling.
The Virtual Optimization Solution
Optimal Solutions Sculptor™ coupled with a multi-objective optimization code produced a design that showed a decrease in drag of more than one percent, a significant amount when the duty cycle of a typical nacelle is considered; this was done while decreasing the mass flow by less than 0.02 percent, increasing the overall efficiency of the nacelle. Moreover, Sculptor avoided time consuming operations on the Computer Aided Design (CAD) model and on the computational grid, since its morphing takes place over the model directly.
A simple optimization was setup for this nacelle. The goal was to reduce drag, while maintaining flow through the nacelle. Three parameters were setup to accomplish this task. The first parameter would change the radius of the inlet, the second would rotate the inlet of the nacelle and the third would translate the inlet in the x direction. Sculptor’s morphing technology was applied over a Computational Fluid Dynamic (CFD) model of the nacelle, to define the optimal surface for drag. The original mesh was read into Sculptor, and the model was prepared for morphing.
Using Arbitrary Shape Deformation (ASD) volumes over 35 different configurations were instantly tested, without the need of re-creating the mesh. By moving the control points, new configurations were created immediately and then submitted to CFD. Finally, the configuration giving the best results was chosen.
Sculptor, coupled with a CFD code, allowed the engineers to reach an optimal aerodynamic design in a just few days, while a CFD analysis on its own would have taken several weeks. The total costs according to the vendor were 90% less with respect to the traditional design method.
"This project proved that mesh deformation was applicable and even desired in our design process. It allowed our designers to make changes to the model without having to go to different departments for help."
Manager at the contractor site