Active control of laminar-turbulent transition

Instability Waves, Commonly Called T-S Waves, Can Be Introduced In A Laminar Boundary Layer By Periodic Heating Of Flush-Mounted Heating Elements. Experiments Have Demonstrated That Nearly Complete Cancellation Of A T-S Wave Excited In This Way Can Be Achieved By Using A Second Downstream Heating Element With A Suitable Phase Shift. As One Application Of The Technique, A Single Element Together With A Feedback Loop Activated By Measured Wall Shear Stress Has Been Used To Reduce The Amplitude Of Naturally Occurring Laminar Instability Waves. A Significant Increase In The Transition Reynolds Number Has Been Achieved.