Aircraft Endurance Improvement through turbulent separation control.

Boundary layer unsteady blowing is one of the most advanced solution to reduce aircraft parasite drag and flow separation at high angles of attack. In this way high lift can be achieved along with low-drag and since endurance is one of the most important performance parameter for some types of aircraft, such as an UAV, it is clear that the ratio CL3/2/CD has to be maximized. Main goal of the present investigation is the exploration of the possible ways for obtaining efficient turbulent boundary layer control, keeping in mind, at the same time, the practical problems connected to the installation of the device in a real wing. Furthermore a global balance of needed power is necessary to prove that the net power balance is in favour of the case in which the control is applied. The work has been mainly addressed to the verification of active control through steady suction and pulsed blowing as an effective tool to delay boundary layer separation. In the first part preliminary theoretical consideration and numerical simulation are presented for steady suction as well as for steady and unsteady blowing. In the second part of the work, experimental investigations on a model wing opportunely instrumented and set in the wind tunnel are presented followed by the discussion of results.