The unsteady quasi-vortex-lattice method with applications to animal propulsion

摘要: In the early theoretical study of aquatic animal propulsion either two-dimensional theory or large aspect-ratio has been generally used. Only recently unsteady lifting-surface with continuous loading approach applied to this problem by Chopra & Kambe (1977). Since it is well known that difficult extend general configurations, a new quasi-continuous method, applicable configurations and yet accurate enough for practical applications, developed in paper. The method an extension steady version Lan (1974) particularly suitable predicting lead-edge suction during harmonic motion.The calculation propulsive efficiency thrust some swept rectangular planforms varying phase angles between pitching heaving motions. It found axis passing through trailing edge root chord reduced frequency k equal 0·75 planform quite sensitive performance may produce drag instead thrust. These characteristics are not shared simulating lunate tails. addition, when leads motion 90°, angle nearly maximum efficiency, inclination caused contributes over portion planform, while, only produced from normal force at = 0·75. also all considered. then dragonfly aerodynamics. shown aerodynamically interacting tandem wings can high if advance flapping hindwing forewing optimum angle. responsible mechanism allows extract wake energy forewing.