GENETIC ALGORITHMS FOR OPTIMIZATION OF AIRSHIP BODIES

摘要

A powerful optimization procedure called Genetic Algorithms has been combined with the aerodynamics calculation method for the flow field around a body of revolution to find the optimal shape. The body profile is described by a first order continuous axial singularity distribution. The solution of the direct problem then gives the radius and inviscid velocity distribution as a function of the location along the axis of symmetry. Viscous effects are considered by means of an integral boundary layer procedure and for determination of the transition location, the forced transition criterion is applied. By avoiding those profiles which results in separation of the boundary layer, the drag can be calculated at the end of the body by using Young's formula. Shape optimizations of airship hulls were performed for different Reynolds number regimes. The objective of our study is to minimize the drag coefficient for a specified design Reynolds number regime. For the present investigations, the Genetic Algorithms (GAs), representing a special artificial intelligence technique for large spaces is applied.