Purpose -Today, the design process of high-lift configurations in industry mainly relies on experts' knowledge, and lacks a simple exploration of the design space. Therefore, the introduction of high-fidelity tools in an optimization chain is now envisaged. The purpose of this paper is to define and solve a realistic high-lift design problem by the use of a constrained evolutionary algorithm, coupled to a Navier-Stokes (RANS) solver. The complete optimization (shape and settings) of a 3-element configuration has been carried out for landing and take-off configurations using a sequential approach. Design/methodology/approach -In a first step, the elements' shapes and settings of the landing configuration have been optimized simultaneously. Then, shapes have been frozen and settings have been optimized for take-off conditions. The flow evaluation during the optimization process is made through 2.5D Navier-Stokes computations on chimera grids. The optimization technique used is an evolutionary algorithm, with a dynamic adaptation of the covariance matrix (CMA-ES). Geometric and aerodynamic constraints have been considered through a dynamic penalization technique of the cost function. Findings -Solutions obtained have been analyzed and compared to the reference initial configuration. In term of cost functions improvement, 5.71 per cent drag reduction has been obtained for landing, and 2.89 per cent improvement on climb index at take-off. Practical implications -Compared to the global optimization process, the use of a sequential approach can be quite efficient. Originality/value -This paper presents a first step for the introduction of recent advanced methods into a design process of high-lift configurations in an industrial environment.
Drag is a design parameter of primary interest in aerodynamics performance evaluation. Its accurate prediction and phenomenological decomposition can provide a valuable physical insight into its origins, and also gives a basis for aircraft design improvements or optimization. In addition, thrust/drag bookkeeping is of primary interest in aircraft design for the decomposition of the airframe and engine contributions to overall aircraft performance. Nevertheless, for innovative configurations such as highly-integrated aero-propulsive concepts this decomposition may be difficult. The above have motivated the investigation of several theories and approaches for drag analysis and decomposition over the last century. The present paper gives an overview of ONERA methods dedicated to the analysis of drag, both from computational fluid dynamics simulations and wind tunnel experiments.
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