School of Mechanical Engineering Nimrod Shay

School of Mechanical Engineering Seminar
Wednesday, May 30, 2018 at 14:00
Wolfson Building of Mechanical Engineering, Room 206

Region of influence of SAOB actuator on a turbulent boundary layer with application to a symmetrical airfoil

Nimrod Shay

MSc Student of Prof. Avi Seifert

School of mechanaical engineering

It is common practice that aircraft control surfaces have symmetric airfoils with low drag and high lift. It is also common to find low aspect ratio wings as control surfaces. Improving the aerodynamic performance of the control surfaces can significantly expand the flight envelope of an aircraft, including shorter take-off and landing, better maneuvering and better stability in side winds. This study is focused on lift enhancement of an SA 14s 2D airfoil and finite span wing constructed from the same airfoil using active flow control (AFC) methods in the form of steady suction and oscillatory blowing (SaOB). The first part of the study deals with investigating the interaction of the SaOB actuator created perturbations with a turbulent flat plate boundary layer. The second part includes wind tunnel testing of a 2D airfoil model; baseline experiments, using suction only and using the combined effect of the SaOB actuator. The chord length of the model is 528mm (constant) and the experiments were performed at Reynolds numbers in the range of 600k-1.4M. The last and final part of the study includes wind tunnel testing of a finite wing model; again baseline experiments as well as SaOB experiments. The mean chord length is 475mm (trapezoidal shaped wing) and the experiments were performed at free-stream velocities of 22, 26 and 33 [m/s] which correspond to Reynolds numbers of 675K, 800K and 1.01M, respectively. It was found that applying AFC can lead to a reduction of up to 50% in the flat plate turbulent boundary layer's momentum thickness. When applied to the specific airfoil, a significant improvement in maximum lift and stall delay was created. Using suction alone proved to be a simple and robust solution with high energy efficiency, while suction combined with oscillatory blowing has a greater potential but require carful care in designing and incorporating the AFC system.