Simulation of laminar turbulent transition, methods for its control and drag reduction

• Main Author: Kang, Kean Lee.
• Other Authors: Jorg Uwe Schluter
• Format: Final Year Project
• Language: English
• Published: 2011
• Subjects: DRNTU::Engineering::Aeronautical engineering::Aerodynamics
• Online Access: http://hdl.handle.net/10356/45979
• Institution: Nanyang Technological University

The objectives of this project were to study the transition process of a laminar boundary layer to a turbulent one and develop methods for the manipulation of the laminar-turbulent transition process. Two methods to trigger the transition process were successfully used, namely the sinusoidal perturbation body force, and by decelerating the flow near to the wall. The former was meant to simulate disturbances that occur naturally in the freestream flow of air. The latter simulates a man-made actuator (such as a plasma actuator) on the surface of a wall that can exert control on the transition process. Both methods mentioned above usually resulted in a bypass transition process. It was also found that transition to turbulent flow can be prevented by accelerating the near wall flow. The main result of this project, however, was from a series of simulations designed to investigate the interactions between all the variables under study. It was found that the actuator could effectively control the total skin friction drag along the wall under all flow conditions studied, including both turbulent and laminar flow. This indicates that the actuator is robust and is a promising candidate for further development in the field of drag reduction. To provide a level of confidence to the conclusions of these simulations, analysis of variances (ANOVA) was also carried out.