Abstract
We present the effect of amplitude on resonance and propulsive characteristics of a pitching flexible panel in quiescent water. The first mode of the resonant frequency (fn1) of the fluid-panel system is determined based on the measured peak lateral excursion of the trailing-edge of the flexible panel at various input frequencies and pitch amplitudes. Both the resonant frequency and peak amplitude ratio a∗ are found to decrease with an increase in the pitch angle. The propulsive force ratio T∗ and power ratio P∗ are defined as the ratio of the mean propulsive force generated and the propulsive power required for the flexible panel to the rigid panel, respectively. The variation of T∗ and P∗ as a function of the frequency ratio f∗=f/fn1 shows that both the propulsive force and the required power are strongly interlinked to the peak lateral excursion of the trailing-edge of the flexible panel. The characteristic flapping velocity of the trailing edge governs the propulsive performance such that propulsive force generation and power required are found to increase with an increase in the characteristic flapping velocity. Moreover, the pitch amplitude can be considered as an input parameter to manipulate the resonance characteristics of a flexible panel, thereby achieving better propulsive performance for various cruise speeds.
Published Version
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