Surrogate Based Aerodynamic Shape Optimization of Tri-lobed Hybrid Airship Envelope

Shape Optimization is one of the significant elements in the design of airships to achieve efficient designs for the desired mission. The shape of an envelope plays a critical role in the design optimization of an airship. The present work is focused on the shape optimization of a tri-lobed envelope of a hybrid airship using surrogate model for estimation of its drag coefficient. The envelope shape is parameterized using seven design variables, which can be varied to obtain different design candidates. To obtain the aerodynamic characteristics of various design candidates, a surrogate model is developed and validated against CFD data. The drag coefficient value of tri-lobed envelope is predicted using the developed surrogate model with less than ±3% error with respect to the result obtained through CFD. An optimal envelope shape with minimum drag is achieved by coupling the surrogate model with evolutionary algorithms, viz., Particle Swarm Optimization (PSO) and Genetic Algorithm (GA). The main objective of this work is to couple the surrogate model with the Multi-disciplinary Design Optimization (MDO) framework for concetual design of a high-altitude long endurance solar-powered hybrid airship.