The Application of Suction and Blowing in Performance Improvement of Transonic Airfoils with Shock Control Bump

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Abstract

Shock Control Bump (SCB) reduces the wave drag in transonic flight. In high Mach transonic flows, the boundary layer separation downstream the bump, induced by the shock wave, results in the poor performance of the SCB. To control the boundary layer separation and to reduce the wave drag for two transonic airfoils, RAE-2822 and NACA-64A010, we investigate the application of two conventional flow control methods, i.e. suction and blowing, to be added to the SCB. An adjoint gradient based optimization algorithm is used to find the optimum shape and location of SCB. The performance of both hybrid suction/SCB (HSS) and hybrid blowing/SCB (HBS) is a function of the sucked or injected mass flow rate, and their position. A parametric study is performed to find the near optimum values of the aerodynamic coefficients and efficiency. A RANS solver is validated and used for this flow analysis. This study shows that both HSS and HBS methods considerably improve the aerodynamic efficiency (L/D), while the HBS method is more effective in control of the shock wave/boundary layer interaction. Using HSS method, the aerodynamic efficiencies of these two airfoils are increased by, respectively, 8.6% and 3.9%, respect to the airfoils with optimized bumps. For HBS configuration, improvements are respectively 13.5% and 9.0%. The best non-dimensional mass flow rate for suction is found to be around 0.003 for both airfoils, and for blowing this is about 0.0025 for RAE-2822 airfoil and about 0.002 for NACA-64A010. The best location for suction and blowing are found to be, respectively, right before and after the SCB.

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Scientia Iranica
Volume 24, Issue 1 - Serial Number 1
Transactions on Mechanical Engineering (B)
February 2017
Pages 274-292

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