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Modification of standard k-epsilon turbulence model for multi-element airfoil application using optimization technique

Darbandi, M ; Sharif University of Technology | 2006

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  1. Type of Document: Article
  2. DOI: 10.2514/6.2006-2829
  3. Publisher: American Institute of Aeronautics and Astronautics Inc , 2006
  4. Abstract:
  5. The use of multi-element airfoils has been known as a major approach to boost up the lift of wing without dramatic increase in its drag. In fact, the configuration helps to reduce the chance of flow separation over the airfoil. However, the use of a complicated geometry such as multi-element airfoil would normally cause complexity in flow behavior. The experience has shown that the flow field complexities cannot be properly modeled using standard two-equation k-epsilon turbulence model. Therefore, it is important to improve the accuracy of general turbulence models in specific applications and complex computational domains. In this work, we extend a suitable objective function based on evaluating the empirical constants of the turbulence model. The essence of defined objective function is to quantify the inaccuracy between the numerical solution and the measurement. The inaccuracy measured by the defined objective function is suitably reduced using a suitable minimization technique. Eventually, the developed optimization algorithm results in new empirical constants different than the classical ones, which are routinely used in the standard model. The modified turbulence model is then utilized to solve a multi-element airfoil configuration consisted of NACA 0012 airfoil section with a Krueger and a trailing flap. This configuration is chosen to verify the modified turbulence model because the experimental pressure coefficient data is available for this case at three different Mach numbers. The current investigation shows that the results of the current modified turbulence model are considerably better than the classical turbulence model
  6. Keywords:
  7. Airfoils ; Channel flow ; Computational complexity ; Mathematical models ; Numerical analysis ; Optimization ; Turbulence ; Flow field complexity ; Flow separation ; Multi element airfoil ; Turbulence models ; Computational fluid dynamics
  8. Source: 24th AIAA Applied Aerodynamics Conference, San Francisco, CA, 5 June 2006 through 8 June 2006 ; Volume 1 , 2006 , Pages 216-227 ; 10485953 (ISSN); 1563478129 (ISBN); 9781563478123 (ISBN)
  9. URL: https://arc.aiaa.org/doi/10.2514/6.2006-2829