Author: B. LjungstreomPublisher:
ISBN:
Category :
Languages : en
Pages : 118
Book Description
Wind Tunnel High Lift Optimization of a Multiple Element Airfoil
Author: B. LjungstreomMulti-element Airfoil Optimization for Maximum Lift at High Reynolds Numbers
Author: Walter O. ValarezoKey Topics for High-Lift Research
Author: National Aeronautics and Space Adm NasaPublisher:
ISBN: 9781729043141
Category :
Languages : en
Pages : 32
Book Description
Future high-lift systems must achieve improved aerodynamic performance with simpler designs that involve fewer elements and reduced maintenance costs. To expeditiously achieve this, reliable CFD design tools are required. The development of useful CFD-based design tools for high lift systems requires increased attention to unresolved flow physics issues. The complex flow field over any multi-element airfoil may be broken down into certain generic component flows which are termed high-lift building block flows. In this report a broad spectrum of key flow field physics issues relevant to the design of improved high lift systems are considered. It is demonstrated that in-flight experiments utilizing the NASA Dryden Flight Test Fixture (which is essentially an instrumented ventral fin) carried on an F-15B support aircraft can provide a novel and cost effective method by which both Reynolds and Mach number effects associated with specific high lift building block flows can be investigated. These in-flight high lift building block flow experiments are most effective when performed in conjunction with coordinated ground based wind tunnel experiments in low speed facilities. For illustrative purposes three specific examples of in-flight high lift building block flow experiments capable of yielding a high payoff are described. The report concludes with a description of a joint wind tunnel/flight test approach to high lift aerodynamics research. Fisher, David and Thomas, Flint O. and Nelson, Robert C. Armstrong Flight Research Center NCC2-5128...
Parameter Optimization Research on Lift-enhancing of Multi-element Airfoil Using Air-blowing
Author: Leading-edge slat optimization for maximum airfoil lift
Author: Lawrence E. OlsonPublisher:
ISBN:
Category : Aerfoils
Languages : en
Pages : 36
Book Description
Two-Dimensional High-Lift Aerodynamic Optimization Using Neural Networks
Author: National Aeronautics and Space Administration (NASA)Publisher: Createspace Independent Publishing Platform
ISBN: 9781723469992
Category :
Languages : en
Pages : 142
Book Description
The high-lift performance of a multi-element airfoil was optimized by using neural-net predictions that were trained using a computational data set. The numerical data was generated using a two-dimensional, incompressible, Navier-Stokes algorithm with the Spalart-Allmaras turbulence model. Because it is difficult to predict maximum lift for high-lift systems, an empirically-based maximum lift criteria was used in this study to determine both the maximum lift and the angle at which it occurs. The 'pressure difference rule, ' which states that the maximum lift condition corresponds to a certain pressure difference between the peak suction pressure and the pressure at the trailing edge of the element, was applied and verified with experimental observations for this configuration. Multiple input, single output networks were trained using the NASA Ames variation of the Levenberg-Marquardt algorithm for each of the aerodynamic coefficients (lift, drag and moment). The artificial neural networks were integrated with a gradient-based optimizer. Using independent numerical simulations and experimental data for this high-lift configuration, it was shown that this design process successfully optimized flap deflection, gap, overlap, and angle of attack to maximize lift. Once the neural nets were trained and integrated with the optimizer, minimal additional computer resources were required to perform optimization runs with different initial conditions and parameters. Applying the neural networks within the high-lift rigging optimization process reduced the amount of computational time and resources by 44% compared with traditional gradient-based optimization procedures for multiple optimization runs. Greenman, Roxana M. Ames Research Center NEURAL NETS; ANGLE OF ATTACK; NAVIER-STOKES EQUATION; LIFT; INCOMPRESSIBLE FLOW; COMPUTERS; AIRFOILS; AERODYNAMIC CONFIGURATIONS; AERODYNAMIC COEFFICIENTS; TURBULENCE MODELS; TRAILING EDGES; SUCTION; GRADIENTS; DRAG; FLAPPING; DEFLECTION; ALGO..
Scientific and Technical Aerospace Reports
Author: Two-dimensional High-lift Aerodynamic Optimization Using Neural Networks
Author: Roxana M. GreenmanParallel Computational Fluid Dynamics '99
Author: D. KeyesPublisher: Elsevier
ISBN: 008053838X
Category : Mathematics
Languages : en
Pages : 477
Book Description
Contributed presentations were given by over 50 researchers representing the state of parallel CFD art and architecture from Asia, Europe, and North America. Major developments at the 1999 meeting were: (1) the effective use of as many as 2048 processors in implicit computations in CFD, (2) the acceptance that parallelism is now the 'easy part' of large-scale CFD compared to the difficulty of getting good per-node performance on the latest fast-clocked commodity processors with cache-based memory systems, (3) favorable prospects for Lattice-Boltzmann computations in CFD (especially for problems that Eulerian and even Lagrangian techniques do not handle well, such as two-phase flows and flows with exceedingly multiple-connected demains with a lot of holes in them, but even for conventional flows already handled well with the continuum-based approaches of PDEs), and (4) the nascent integration of optimization and very large-scale CFD. Further details of Parallel CFD'99, as well as other conferences in this series, are available at http://www.parcfd.org
Concepts for Lift Improvements of a High-Lift Military Airfoil
Author: Publisher:
ISBN:
Category :
Languages : en
Pages : 11
Book Description
This paper describes the computational analysis of several concepts to improve the maximum lift of a military high-lift airfoil configuration. The computational results are compared with the wind-tunnel data obtained for a gap and overhang study and a Gurney flap study. In the wind tunnel experiments, optimizing the gap and over-hang and adding a Gurney flap provided the largest increases, on the order of 3-4%. These trends were duplicated in the CFD analyses. Incremental lift improvements were found using the Gurney flap and by adjusting the gap and overhand of the flap. Life improvement was also obtained by perturbing the leading edge portion of the trailing edge flap. It was found that the lift enhancements were additive, the maximum lift increased by 14% using a Gurney flap and the flap at the optimum gap and overlap. The CFD analyses used an unstructured Navier-Stokes code. The wind tunnel tests were a cooperative effort between the Navy, Boeing (St. Louis), and NASA Langley Research Center (LaRC) and were conducted in the NASA LaRC Low Turbulence Pressure Tunnel. Forces and moments and other parameters were measured on a two-dimensional airfoil model of an advanced fighter win section configured with a deflected leading edge flap, shroud and a slotted trailing edge flap.