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Aerodynamic efficiency of an airplane wing can be improved either by increasing its lift generation tendency or by reducing the drag. Recently, Bio-inspired designs have been received greater attention for the geometric modifications of airplane wings. One of the bio-inspired designs contains sinusoidal Humpback Whale (HW) tubercles, i.e., protuberances exist at the wing leading edge (LE). The tubercles have excellent flow control characteristics at low Reynolds numbers. The present work describes about the effect of tubercles on swept back wing performance at various Angle of Attack (AoA). NACA 0015 and NACA 4415 airfoils are used for swept back wing design with sweep angle about 30°. The modified wings (HUMP 0015 A, HUMP 0015 B, HUMP 4415 A, HUMP 4415 B) are designed with two amplitude to wavelength ratios (η) of 0.1 & 0.24 for the performance analysis. It is a novel effort to analyze the tubercle vortices along the span that induce additional flow energy especially, behind the tubercles peak and trough region. Subsequently, Co-efficient of Lift (CL), Co-efficient of Drag (CD) and boundary layer pressure gradients also predicted for modified and baseline (smooth LE) models in the pre & post-stall regimes. It was observed that the tubercles increase the performance of swept back wings by the enhanced CL/CD ratio in the pre-stall AoA region. Interestingly, the flow separation region behind the centerline of tubercles and formation of Laminar Separation Bubbles (LSB) were asymmetric because of the sweep.

Numerical simulations of turbulent flow over a NACA0012 aerofoil attached with vortex generators (VG) are carried out over a wide range of angles of attack at Re=5.5×10 5 The three-dimensional Reynolds averaged Navier-Stokes equations along with closure equations of Spalart-Allmaras turbulence model are solved using commercial package FLUENT. The addition of VG results in increased lift-coefficient and reduced drag-coefficient at large incident angles. The influence of VG on the fluid flow and aerodynamic forces acting on the aerofoil are reported in this paper, with the emphasis on how the addition of the small vanes helps to delay the onset of stall. Comparison of streamline patterns, pressure coefficient and contour plots of field variables between the clean aerofoil and VG fitted aerofoil help us to understand how the vortex generator energises the boundary layer flow and hence delay the stall.

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The aerodynamic behavior of sweptback wing configurations with bio-inspired humpback whale (HW) leading-edge (LE) tubercles has been investigated through computational and experimental techniques. Specifically, the aerodynamic performance of tubercled wings with symmetric (NACA 0015) and cambered (NACA 4415) airfoils is validated against the baseline model at various angles of attack ([Formula: see text]. The [Formula: see text]/[Formula: see text] ratio of the HW flipper is strategically reduced to 0.15 for ascertaining the flow control potential of the bio-inspired wings with sweptback configuration. It is a novel effort to quantify the effect of the leading-edge protuberances on stall delay, flow separation control and distribution of streamline vortices at unique [Formula: see text]/[Formula: see text] ratio outside the thickness range of HW flipper morphology. Four tapered sweptback wing models (Baseline A, Baseline B, HUMP 0015, HUMP 4415) are used with the amplitude-to-wavelength ([Formula: see text] ratio of 0.24 and Reynolds number about [Formula: see text]. The chordwise pressure distributions are recorded at the peak, mid and trough regions of the tubercled wings through a detailed wind tunnel testing and validated with numerical analysis. Additionally, the flow characteristics over the bio-inspired surfaces have been qualitatively analyzed through the laser flow visualization (LFV) technique to reveal the influence of laminar separation bubbles (LSBs). The essential aerodynamic characteristics such as boundary layer trip delay, vortex mixing, stall delay, and flow control at different AoA are addressed through consistent experimental data. As the sweptback configuration is a primary choice for airplane wings, the improved aerodynamic characteristics of the tubercled wings can be effectively utilized for the design of novel lifting surfaces, hydroplanes and wind turbines in the near future.