Two-dimensional Transonic Flow Past Airfoils

Two-dimensional Transonic Flow Past Airfoils
Author: Yung-Huai Kuo
Publisher:
Total Pages: 54
Release: 1951
Genre: Aerodynamics, Transonic
ISBN:

The problem of constructing solutions for transonic flow over symmetric airfoils is treated for simplification of the mapping of the incompressible flow is emphasized. In the case of a symmetric Joukowski airfoil without circulation the mapping is relatively simple, but the coefficients in the power series are difficult to evaluate. As a means of simplification an approximate flow is used which differs only slightly from the exact incompressible one when the thickness is small. Flow with circulation is also considered by the same method.

On the Validation of a Code and a Turbulence Model Appropriate to Circulation Control Airfoils

On the Validation of a Code and a Turbulence Model Appropriate to Circulation Control Airfoils
Author: National Aeronautics and Space Adm Nasa
Publisher: Independently Published
Total Pages: 26
Release: 2018-10-18
Genre: Science
ISBN: 9781728925509

A computer code for calculating flow about a circulation control airfoil within a wind tunnel test section has been developed. This code is being validated for eventual use as an aid to design such airfoils. The concept of code validation being used is explained. The initial stages of the process have been accomplished. The present code has been applied to a low-subsonic, 2-D flow about a circulation control airfoil for which extensive data exist. Two basic turbulence models and variants thereof have been successfully introduced into the algorithm, the Baldwin-Lomax algebraic and the Jones-Launder two-equation models of turbulence. The variants include adding a history of the jet development for the algebraic model and adding streamwise curvature effects for both models. Numerical difficulties and difficulties in the validation process are discussed. Turbulence model and code improvements to proceed with the validation process are also discussed. Viegas, J. R. and Rubesin, M. W. and Maccormack, R. W. Ames Research Center RTOP 505-60-11

Numerical Optimization of Circulation Control Airfoils

Numerical Optimization of Circulation Control Airfoils
Author: Tsze C. Tai
Publisher:
Total Pages: 52
Release: 1980
Genre:
ISBN:

A numerical procedure developed for optimizing the circulation control airfoils is presented. The procedure finds the optimum basis airfoil shapes subjected to specified flow conditions and geometric constraints. It consists of a numerical optimization code for linear constrained problems coupled with a viscous-potential flow interaction analysis for necessary viscous-inviscid flow field calculations. The desired airfoil shape is defined by a combination of baseline shapes representative of airfoils suitable for circulation control purposes. The coefficients of these basis vectors are then used as the design variables in the optimization process. Three baseline shapes (a cambered ellipse, a cambered ellipse with a drooped trailing edge, and a cambered ellipse with a logarithmically spiralled trailing edge) are employed for special contouring of the trailing edge geometry. With some minor modification of the analysis method, the combined program allows optimization for maximum lift without substantial difficulty; but for minimizing the drag, further improvement of the analysis method is required.

Computational Analysis of Circulation Control Airfoils

Computational Analysis of Circulation Control Airfoils
Author:
Publisher:
Total Pages:
Release: 2004
Genre:
ISBN:

Current projections for future aircraft concepts call for stringent requirements on high-lift and low cruise-drag. The purpose of this study is to examine the use of circulation control, through trailing edge blowing, to meet both requirements. This study was conducted in two stages: (i) validation of computational fluid dynamic procedures on a general aviation circulation control airfoil and (ii) a study of an adaptive circulation control airfoil for controlling lift coefficients in the low-drag range. In an effort to validate computational fluid dynamics procedures for calculating flows around circulation control airfoils, the commercial flow solver FLUENT was utilized to study the flow around a general aviation circulation control airfoil. The results were compared to experimental and computational fluid dynamics results conducted at the NASA Langley Research Center. This effort was conducted in three stages: (i) a comparison of the results for free-air conditions to those from previously conducted experiments, (ii) a study of wind-tunnel wall effects, and (iii) a study of the stagnation-point behavior. In general, the trends in the results from the current work agreed well with those from experiments, some differences in magnitude were present between computations and experiments. For the cases examined, FLUENT computations showed no noticeable effect on the results due to the presence of wind-tunnel walls. The study also showed that the leading-edge stagnation point moves in a systematic manner with changes to the jet blowing coefficient and angle of attack, indicating that this location can be sensed for use in closed-loop control of such airfoil flows. The focus of the second part of the study was to examine the use of adaptive circulation control on a natural laminar flow airfoil for controlling the lift coefficient of the low-drag range. In this effort, adaptive circulation control was achieved through blowing over a small mechanical flap that can be deflec.

NASA SP.

NASA SP.
Author:
Publisher:
Total Pages: 580
Release: 1991
Genre: Aeronautics
ISBN: