Numerical Analysis of Suppression of Laminar Bubble at Low Reynolds Number Using Different Protrusions

Abstract

Flow over airfoil at low Reynolds numbers encounters separation bubble which can be generally controlled by active or passive methods. In this project work passive method is used. The effectiveness of bubble burst control plate at different locations (5 and 7.5 % of the chord of airfoil) on an NACA 631-012 airfoil section for laminar separation bubble burst delay, stall separation, lift augmentation, and drag reduction will be analyzed computationally using commercial CFD code ANSYS FLUENT. The effectiveness of burst control plate is governed by its height, width, geometry, and distance between leading edge of the airfoil and trailing edge of plate. Flow patterns are analyzed and they are compared with experimental results. The results suggest that the stall angle of the original Airfoil (without the burst control plate) occurs at 10°, and it is successfully postponed to 13o (Airfoil with Triangular plate) and 14o (Airfoil with Rectangular plate) when the burst control plate is attached onto the Airfoil. The lift forces were calculated for a range of angle of attack from 0 to 15o. The overall analysis 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.