Computational Optimization of a Natural Laminar Flow Experimental Wing Glove
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Under the National Aeronautics and Space Administration's Environmentally Responsible Aviation Program, a laminar flow wing glove is being designed to demonstrate the applicability of swept-wing laminar flow control using discrete roughness elements at chord Reynolds numbers relevant to transport class aircraft. The project, Discrete Roughness Elements Laminar Flow Glove Experiment, will use a Gulfstream III business jet aircraft (Gulfstream Aerospace Corporation, Savannah, Georgia) as a host aircraft for the flight research experiment. The process of developing the wing glove for the project starts with the initial design of a target pressure distribution meeting a set of performance requirements for successful DRE application, assuming an infinite swept wing, and using linear stability theory. An inverse design process produces two initial airfoil shapes that are linearly lofted into a three-dimensional (3D) glove shape, which is mounted and faired on the port wing of a GIII computer-aided design model. The glove shape serves as the initial condition for an optimizer with the objective of producing 3D glove geometry with a spanwise-uniform pressure distribution that matches the target pressure distribution as closely as possible. TRANAIR (Calmer Research Corporation, Cato, New York), a non-linear full potential solver with a coupled boundary layer code is used as the main tool in the design and optimization process of the 3D glove shape. The optimization algorithm uses the Class-Shape-Transformation (CST) method to perturb the geometry with constraints derived from the project requirements and GIII configuration. Results show that with the appropriate inputs, the optimizer is able to match the major features of the target pressure distribution across the entire span of the wing glove. The final glove smoothness and shape were very sensitive to the number of design variables and the format and weighting of the objective function. The number of constraints and design variables also greatly affects the computational time. Linear boundary-layer stability computations demonstrate that stability characteristics conducive to DRE application are nominally achieved across the span of the optimized glove. Copyright © 2012 by the American Institute of Aeronautics and Astronautics, Inc.
author list (cited authors)
Hartshorn, F., Belisle, M., & Reed, H.