A turbulent boundary layer greatly increases the drag on a wing, and therefore aircraft fuel consumption. By delaying the transition of organized, laminar flow into disorganized, turbulent flow, billions a year can be saved in fuel costs. One way that this transition can be delayed is by using a vibrating surface element to suppress the Tollmien-Schlichting (TS) waves responsible.
The Natural Laminar Flow (NLF) airfoil series is designed to passively delay the growth of TS waves. An array of Piezoelectric-Driven Oscillation Surface (PDOS) actuators are mounted on the suction side of the airfoil. The upstream actuator will excite a TS frequency that will grow and travel downstream. A second actuator will apply the anit-phase of the TS wave and use the destructive interference to reduce and eliminate the TS wave. Particle Image Velocimetry (PIV) will be used to quantify the results. By phase-locking the PIV data, the small velocity flucuations may be visualized.
The long term goal is to achieve closed loop control on natural TS waves on the NLF airfoil.
Related Publications:
- Dell'Orso, H., "Feasibility of Using Dynamically Oscillating Surfaces to Control Tollmien-Schlichting Waves." Rensselaer Polytechnic Institute M.S. Thesis, August 2016.
- Amitay, M., Tuna, B.A., and Dell'Orso, H., "Identification and Mitigation of T-S Waves Using Localized Dynamic Surface Modification." Physics of Fluids, Volume 28, Issue 6, DOI: 10.1063/1.4953844, 2016.