纳米仿生技术.pptx

;CONTENTS;;Use of the flipper by humpback whales;As hydroplanes used in turning, flippers must operate at high angles of attack while maintaining lift, which could cause the stall and centripetal force reduced. For the whale, the ability to turn tightly would be lost and the prey could escape.;;2 _______________ Angle of attack;Fig 3 Schematic diagram of flow separation;Humpback whales utilize extremely mobile, wing-like flippers for banking and turning. Large rounded tubercles along the leading edge of the flipper are morphological structures that are unique in nature. ?Its thickness is about 20% of the chord. Fig 1 (b) clearly depicts shaped cross section of the humpback whale flippers.;Hydrodynamics of tubercles;;;Fig 7 Wind tunnel experiments data;;Top surface;;;Energy efficiency is enhanced by addition of tubercles on fan blades . Envira-North Systems Ltd produces industrial ceiling fans for large buildings with the tubercle modification. A high-volume, low-speed (HVLS) model with a 24-foot diameter of five blades is reported to be 25% more efficient and consumes 20% less electricity to operate than a 10 blade configuration. In addition, the HVLS fan is 20% quieter . Suppression of tonal noise by the addition of tubercles to an airfoil in a low-speed wind tunnel was observed (Hansen et al. 2010). Tonal noise is most effectively reduced by tubercles of large amplitude and smaller wavelength.;Fig 11 Surfboard skeg based on leading-edge tubercles of the humpback whale’s flipper;;Connection with my topic MAX phase sometimes can be used as nano-rod to promote the heat transfer of the fluid. So we can add some tubercles on the surface to change the fluid field, reduce the drag , facilitating the sufficient heat transfer.;THANKS!