Experimental Investigation on Laminar Separation Bubble Over an Airfoil – A Review

Objectives: To provide comprehensive literature survey of laminar separation bubble over a low Reynolds number airfoil with reference to the conventional and non-conventional experimental technique using wind tunnel. Methods/Statistical Analysis: For more convenient understanding, the various wind tunnel experimental techniques and advanced research progress in this field is presenting in table format. The table shows characteristics of laminar separation bubble over airfoil at different Reynolds number for various conditions. The table critiques the proof-based entire data about the Laminar Separation Bubble (LSB) traits (height and period), go with the flow traits differentiated, transition and reattachment locations and go with the flow visualization over airfoil were experimentally discovered at various angles of attack and Reynolds range, respectively. Findings: The current evidence supports the view that laminar separation bubble characteristics, behaviour and its effect over an airfoil. Most studies in this field have been done experimentally using Wind Tunnel with various techniques i.e., Surface Oil Flow Technique, Particle Image Velocimetry (PIV), Infrared Thermography (IT), Force Measurement and Hot-Wire Experiments, Smoke-Wire Experiment, Multi-line Molecular Tagging Velocimetry, Volumetric Three-Component Velocimetry (V3V), Time-resolved surface pressure sensor arrays, ESP (Electronically Scanned Pressure), Embedded Laser Doppler Velocimetry (ELDV), Fast Fourier Transform (FFT). Application/Improvements: This paper describes the various techniques and characteristics of LSB which will be beneficial to design the low Reynolds number airfoil in order to minimize the drag and increases the aerodynamic efficiency for industrial applications.