Flow Control of an Airfoil via Injection and Suction

We report on an experimental study of a Clark-Y airfoil subjected to both flow injection and suction in the manner of the coflow-jet flow control method. The study was conducted at Reynolds numbers of 7.4 x 10(4) and 1.3 x 10(5) for three different jet momentum coefficients: C(mu) = 0.02, 0.04, and 0.16. Some numerical computations are used to assess the extent to which they are adequate for engineering analysis and design of the coflow-jet method. The results clearly demonstrate the lift augmentation capability, particularly at high incidence angles. The increase in lift and stall margin depends on the momentum coefficient, and for the range tested, the increase in the integral of the airfoil static pressure distribution varies from 40 to 100%. The results suggest that the collow-jet airfoil is more effective when both injection and suction are used simultaneously, compared with the case in which they are individually used. A first-order analysis of the combined merits of injection and suction indicate that these processes are not strongly coupled to each other and thus may possibly be analyzed separately.