Separation Lines for Laminar Separation Bubble and Propagation of Stall over Finite Wing at Transition Regime Reynolds Number

Flow separation over a 3D wing, both local at low angles of attack and that which begins at a section and then engulfs the entire wing at the higher angles of attack is studied using experiments and CFD. The pressure measured from pressure ports located on the root section of the 3D wing is used to calculate the pressure coefficient and oil flow visualization conducted to study separation lines. The location and length of the separated zone along wing-span is calculated. Statistical analysis of the data extracted from the oil flow visualization is used to generate curve-fit separation and reattachment lines. The data shows lines to be third-order polynomial. Study indicates that the location of laminar separation bubbles is more sensitive to the angle of attack as compared to the Reynolds number. At the higher angles of attack, the effect of the Reynolds number and the angle of attack on stall progression is studied. The velocity profile in the boundary layer at five different locations along wing-span is calculated at the angles of attack near complete wing stall. Sections near wing-root and the wing tips are studied in detail and inferences drawn on stall progression in cambered wing. A comprehensive study of flow separation and laminar separation bubble on a 3D wing can be used as basis of design for active flow control.