Home

Browse
Communities
& Collections

Issue Date
Author
Title
Subject

Sign on to:

My Account
authorized users

Edit Profile

Help
 Please use this identifier to cite or link to this item: http://hdl.handle.net/1807/17772

 Title: Efficient Algorithms for Future Aircraft Design: Contributions to Aerodynamic Shape Optimization Authors: Hicken, Jason Advisor: Zingg, David W. Department: Aerospace Science and Engineering Keywords: induced dragshape optimizationaircraft designcomputational fluid dynamicsb-spline volumeNewton KrylovGMRESGCROTadjointsummation-by-partssimultaneous approximation terms Issue Date: 24-Sep-2009 Abstract: Advances in numerical optimization have raised the possibility that efficient and novel aircraft configurations may be discovered'' by an algorithm. To begin exploring this possibility, a fast and robust set of tools for aerodynamic shape optimization is developed. Parameterization and mesh-movement are integrated to accommodate large changes in the geometry. This integrated approach uses a coarse B-spline control grid to represent the geometry and move the computational mesh; consequently, the mesh-movement algorithm is two to three orders faster than a node-based linear elasticity approach, without compromising mesh quality. Aerodynamic analysis is performed using a flow solver for the Euler equations. The governing equations are discretized using summation-by-parts finite-difference operators and simultaneous approximation terms, which permit nonsmooth mesh continuity at block interfaces. The discretization results in a set of nonlinear algebraic equations, which are solved using an efficient parallel Newton-Krylov-Schur strategy. A gradient-based optimization algorithm is adopted. The gradient is evaluated using adjoint variables for the flow and mesh equations in a sequential approach. The flow adjoint equations are solved using a novel variant of the Krylov solver GCROT. This variant of GCROT is flexible to take advantage of non-stationary preconditioners and is shown to outperform restarted flexible GMRES. The aerodynamic optimizer is applied to several studies of induced-drag minimization. An elliptical lift distribution is recovered by varying spanwise twist, thereby validating the algorithm. Planform optimization based on the Euler equations produces a nonelliptical lift distribution, in contrast with the predictions of lifting-line theory. A study of spanwise vertical shape optimization confirms that a winglet-up configuration is more efficient than a winglet-down configuration. A split-tip geometry is used to explore nonlinear wake-wing interactions: the optimized split-tip demonstrates a significant reduction in induced drag relative to a single-tip wing. Finally, the optimal spanwise loading for a box-wing configuration is investigated. URI: http://hdl.handle.net/1807/17772 Appears in Collections: DoctoralInstitute for Aerospace Studies - Doctoral theses

Files in This Item:

File Description SizeFormat
View/Open