Parameter Optimization Research on Lift-enhancing of Multi-element Airfoil Using Air-blowing PDF Download

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Languages : en
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Author: National Aeronautics and Space Administration (NASA)
Publisher: Createspace Independent Publishing Platform
ISBN: 9781723047541
Category :
Languages : en
Pages : 158

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An experimental and computational investigation of the effect of lift-enhancing tabs on a two-element airfoil has been conducted. The objective of the study was to develop an understanding of the flow physics associated with lift-enhancing tabs on a multi-element airfoil. An NACA 63(2)-215 ModB airfoil with a 30% chord fowler flap was tested in the NASA Ames 7- by 10-Foot Wind Tunnel. Lift-enhancing tabs of various heights were tested on both the main element and the flap for a variety of flap riggings. A combination of tabs located at the main element and flap trailing edges increased the airfoil lift coefficient by 11% relative to the highest lift coefficient achieved by any baseline configuration at an angle of attack of 0 deg, and C(sub 1max) was increased by 3%. Computations of the flow over the two-element airfoil were performed using the two-dimensional incompressible Navier-Stokes code INS2D-UP. The computed results predicted all of the trends observed in the experimental data quite well. In addition, a simple analytic model based on potential flow was developed to provide a more detailed understanding of how lift-enhancing tabs work. The tabs were modeled by a point vortex at the air-foil or flap trailing edge. Sensitivity relationships were derived which provide a mathematical basis for explaining the effects of lift-enhancing tabs on a multi-element airfoil. Results of the modeling effort indicate that the dominant effects of the tabs on the pressure distribution of each element of the airfoil can be captured with a potential flow model for cases with no flow separation. Ashby, Dale L. Ames Research Center LIFT; AIRFOILS; TABS (CONTROL SURFACES); WIND TUNNEL TESTS; ANGLE OF ATTACK; NAVIER-STOKES EQUATION; COMPUTATIONAL FLUID DYNAMICS; GRID GENERATION (MATHEMATICS); AIRFOIL PROFILES; FLAPS (CONTROL SURFACES); TRAILING EDGES; INCOMPRESSIBLE FLOW; DATA CORRELATION; PREDICTION ANALYSIS TECHNIQUES; VORTICES; POTENTIAL FLOW; PRESSURE DISTRIBUTION; AERODYNAMIC C...

Author: Walter O. Valarezo
Publisher:
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Languages : en
Pages : 8

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Author: Dale L. Ashby
Publisher:
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Category : Aerofoils
Languages : en
Pages : 164

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Author: James C. Ross
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Category :
Languages : en
Pages :

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Author: Marianna Braza
Publisher: Springer Nature
ISBN: 9813349603
Category : Technology & Engineering
Languages : en
Pages : 384

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This book contains a thorough and unique record of recent advances in the important scientific fields fluid–structure interaction, acoustics and control of priority interest in the academic community and also in an industrial context regarding new engineering designs. It updates advances in these fields by presenting state-of-the-art developments and achievements since the previous Book published by Springer in 2018 after the 4th FSSIC Symposium. This book is unique within the related literature investigating advances in these fields because it addresses them in a complementary way and thereby enhances cross-fertilization between them, whereas other books treat these fields separately.

Author: Bruce L. Storms
Publisher:
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Category : Aerofoils
Languages : en
Pages : 7

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Author: National Aeronautics and Space Administration (NASA)
Publisher: Createspace Independent Publishing Platform
ISBN: 9781723469992
Category :
Languages : en
Pages : 142

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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..

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ISBN:
Category :
Languages : en
Pages : 75

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A review of techniques aimed at maximizing C1/Cd and C1 for multi- element airfoils showed the need for more exhaustive testing of possible configurations of flap deflection, slot geometry and airfoil angle of attack. For a typical 4-element airfoil, the number of possible configurations can easily be in the billions. A new technique, based on evolution strategy, has been developed for the problem of optimizing a multi-element airfoil with respect to its envelope of maximum C1/Cd versus C1. This technique was applied to an airfoil having a slotted leading edge flap and a double-slotted trailing edge flap using an existing computer program for 2D subsonic multi-element airfoils to provide values of aerodynamic coefficients. Although limitations of the program precluded the full determination of the envelope of C1/Cd vs C1 the problem of maximizing C1/Cd for a minimum C1 constraint was solved. The result of testing approximately 400 configurations generated by the random mutation- natural selection procedure of evolution strategy was an 8-fold increase in C1/ Cd iwth a 12% increase in C1 over the initial geometry.

Author: Paul G. Carrannanto
Publisher:
ISBN:
Category : Aerofoils
Languages : en
Pages : 320

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