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Coanda surface geometry optimization for multi-directional co-flow fluidic thrust vectoring

Saghafi, F ; Sharif University of Technology

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  1. Type of Document: Article
  2. DOI: 10.1115/GT2009-59715
  3. Abstract:
  4. The performance of Co-flow fluidic thrust vectoring is a function of secondary flow characteristics and the fluidic nozzle geometry. In terms of nozzle geometry, wall shape and the secondary slot aspect ratio are the main parameters that control the vector angle. The present study aims to find a high quality wall shape to achieve the best thrust vectoring performance, which is characterized by the maximum thrust deflection angle with respect to the injected secondary air. A 3D computational fluid dynamics (CFD) model is employed to investigate the flow characteristics in thrust vectoring system. This model is validated using experimental data collected from the deflection of exhaust gases of a small jet-engine integrated with a multi-directional fluidic nozzle. The nozzle geometry is defined by the collar radius and its cut-off angle. In order to find the best value of these two parameters, Quasi-Newton optimization method is utilized for a constant relative jet momentum rate, a constant secondary slot height and insignificant step size. In this method, the performance index is described as a function of thrust deflection angle. Optimization parameters (wall geometric parameters) are estimated in the direction of gradient, with an appropriate step length, in every iteration process. A good guess of initial optimization parameters could lead to a rapid convergence towards an optimal geometry and hence maximum thrust deflection angle. Examination over a range of geometric parameters around the optimum point reveals that this method promises the best performance of the system and has potential to be employed for all the other affective factors. Copyright © 2009 by ASME
  5. Keywords:
  6. Affective factors ; Best value ; Co-flow ; Cut-off ; Deflection angles ; Experimental data ; Flow characteristic ; Fluidic thrust vectoring ; Geometric parameter ; High quality ; Initial optimization ; Iteration process ; Jet momentum ; Main parameters ; Maximum thrust ; Multi-directional ; Nozzle geometries ; Optimal geometry ; Optimization parameter ; Performance indices ; Quasi-Newton optimization method ; Rapid convergence ; Secondary air ; Secondary flow characteristics ; Slot height ; Step length ; Step size ; Surface geometries ; Thrust vectoring ; Thrust vectoring systems ; Two parameter ; Vector angle ; Aspect ratio ; Computational geometry ; Deflection (structures) ; Exhaust gases ; Nozzles ; Optimization ; Three dimensional ; Computational fluid dynamics
  7. Source: Proceedings of the ASME Turbo Expo: Power for Land, Sea, and Air ; Volume 5 , 2009 , Pages 183-189 ; 9780791848869 (ISBN)
  8. URL: http://proceedings.asmedigitalcollection.asme.org/proceeding.aspx?articleid=1647234