Icase Observations regarding Use of Advanced Cfd Analysis , Sensitivity Analysis , and Design Codes in Mdo

Observations regarding the use of advanced computational fluid dynamics (CFD) analysis, sensitivity analysis (SA), and design codes in gradient-based multidisciplinary design optimization (MDO) reflect wr perception of the interactions required of CFD and our experience in recent aerodynamic design optimization studies using CFD. Sample results from these latter studies are summarized for conventional optimization (analysis-SA codes) and simultaneous analysis and design optimization (design code) using both Euler and Navier-Stokes flow approximations. The amount of computational resources required €or aerodynamic design using CFD via analysisSA codes is greater than that required for design codes. Thus, an MDO formulation that utilizes the more efficient design codes where possible is desked. However, in the aerovehicle MDO problem, the various disciplines that are involved have Merent design points in the flight envelope; therefore, CFD analysis-SA codes are required at the aerodynamic “off design” points. The suggested MDO formulation is a hybrid multilevel optimization procedure that consists of both multipoint CFD analysis-SA codes and multipint CFD design codes that perform suboptimizations. ”his research was suppcnted by the National Aeronautics and Space Administration under NASA Contract NAS1-19480 while the seamd author was in residence at the Institute for Computer Applicatias in Science and Engineering. NASA Langley Research Center, Hampm, VA 23681-1. f ?he work of the second and third authors was partidy supported by NASA Grant NAG-1-1265.