Bubble Burst Control for Stall Suppression on a NACA 631-012 Airfoil

Abstract

Based on the novel concepts of the burst control plate, the current article aims to demonstrate the effectiveness of the burst control plate attached at different locations (5%, 7.5% and 10% of the chord of the airfoil) on a NACA 631-012 airfoil section for laminar separation bubble burst delay, stall suppression, lift augmentation and drag reduction at a chord Reynolds number of 1.3x10 5 . The effectiveness of the burst control plate is governed by its height, width, geometry and the distance between the leading-edge of the airfoil and the trailing-edge of the plate. Flow patterns around the airfoil with and without the plate attachment were studied with an aid of smoke flow visualization. The results suggest that the stall angle of the original airfoil (without the burst control plate) occurs at 10 o and it is successfully postponed to approximately 13 o when the burst control plate is attached onto the airfoil. Lift and drag forces were measured for a range of angle-of-attack from 0 o to +20 o . The experimental results have shown that the lift generated on the NACA 631-012 airfoil with the plate attachment and above 9 o angle-of-attack is significantly higher than the original airfoil, while the drag is sufficiently reduced. The overall results demonstrated the application of the burst control plate on the NACA 631-012 airfoil can be effective means of bubble burst control and airfoil stall suppression in low speed flows.