LAMINAR-TURBULENT TRANSITION PREDICTION ON THREE-DIMENSIONAL WINGS, INCLUDING AIRFOIL SHAPE OPTIMIZATION
Abstract
Laminar-turbulent transition prediction and control remain elusive objectives of the aerospace industry, despite decades of theoretical, numerical, experimental and flight-testing efforts aiming at understanding the physics of modal and non-modal linear mechanisms, and the nonlinear interaction of the most unstable disturbances that lead a laminar flow to transition and turbulence. In recent times, state-of-the-art analysis methods and numerical tools have been developed to interrogate flows with respect to their linear and nonlinear instability. In particular, progress with accurate and efficient computation of compressible laminar shock-dominated steady states enables global modal and nonmodal instability analysis of transonic, supersonic and hypersonic flows over or througharbitrarily complex geometries.The present effort will address modal and non-modal global linear instability analysis and laminar-turbulent transition on aircraft wings in supersonic flight, in an integrated framework that includes airfoil-shape optimization from both the point of view of overall aerodynamic characteristics, as well as in terms of transition delay on the wing surface. Such improvements will make substantial contributions toward next-generation aircraft meeting ambitious environmental protectiontargets in terms of both reduced fuel consumption and noise mitigation.Over the last decades, work performed in Prof. Theofilis’ group has been focused on global instability theory, whereas the group of Prof. Alves has recently been developing tools to generate the appropriate instability free laminar steady states. Supported by AFOSR, both groups have been collaborating closely to quantify linear instabilities and laminar-turbulent transition mechanisms in compressible flows. The research of the two groups has been supported by state-of-the-artshock-dominated steady laminar flow computations and the subsequent massively parallel numerical solution of complex non-symmetric eigenvalue and singular value problems, respectively governing linear modal and non-modal flow instability.In the proposed effort, Prof. Alves’ group will be update its current tools to deliver high-order steady laminar flows in any complex three-dimensional geometries in contrast to standard secondorder spatial discretization solvers widely used in the literature and, on occasion, yielding nonphysical results containing spurious oscillations that can be misled as flow instabilities. Two special cases will be used for validation of the tools to be developed; the compressible similar and non-similarboundary-layer as well as the high-speed flow over an axisymmetric cylinder flare. The Linear Global stability analysis for Hypersonic Transition (LiGHT) code of Prof. Theofilis’ group will be updated to solve the equations governing linear perturbations in the presence of shocks both as part of the analyzed flowfield and in the context of novel boundary closures. The linearized operator generated for both modal and non modal stability will be generated in parallel way, in order to reduce current bottlenecks in communication between processors that, as the problem size increases, have led to disproportionately large computing time being spent in forming the matrix rather than solving the eigenvalue or singular value problem. Finally, topology optimization, currently under developmentat USP with FAPESP support, will be integrated into the code and applied of optimization of three-dimensional wings.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Mar 07, 2023
- Source ID
- FA95502210033
Entities
People
- Vassilis Theofilis
Organizations
- Air Force Office of Scientific Research
- Fundação de Apoio à Universidade de São Paulo
- United States Air Force