2.2. Numerical method validation
In order to verify whether the developed numerical simula-tion technology and established flow control model can accurately capture the subtle characteristics of the jet flow field, a Seifert TAU0015 airfoil flow control experiment [5,6,13]is selected for the numerical validation. Four sub-iteration steps are used in the cal-culation (four complete multigrid cycles) and a complete flow cycle is divided into 80 pieces. Generally, after 25∼35cycles of calcula-tion, a stable periodic flow solution after control can be achieved.
Fig.1shows the calculation results of the TAU0015 airfoil synthetic jet control, which are compared to the experimental data from Seifert and the OSC2D program results [14], wherein (a)shows the control effect of the airfoil under different angles of attack; (b)is the influence of the jet momentum coefficient on the control efficiency; and CLis obtained based on calculation of a complete jet circle time-averaged Cpintegral. As shown in the figure, when the airfoil angle of attack is greater than12◦, re-sults of OSC2D and calculation in this paper sharply over-predict the experimental data even though there are consistent general variations. This is due to the fact that in the experiment, the sen-sors could not be installed near the flow actuator, and thereby the influence of the pressure peak at the leading edge on the aero-dynamic characteristics could not be included. Calculations from Joslin and Viken also show that the experiment conducted by Seifert underestimated the lift characteristics of the airfoil [15]. Therefore, the selected numerical method and the established flow control model in this paper can effectively capture the flow field characteristics of the synthetic jet with good reliability and accu-racy.
3. Calculation model