Abstract: The microbubble drag reduction of underwater vehicle is researched using a self-designed driving device, a high speed camera and a six-component force balance for studying the characteristics of microbubble flow and microbubble drag reduction during the pitching movement of underwater vehicle. The results show that the discrete microbubbles are uniformly distributed on the surface of the underwater vehicle at low air injection rate. During the pitching movement of an underwater vehicle, the axial force coefficient, lateral force coefficient, drag coefficient and lift coefficient are all sinusoidal, and the change period is basically synchronized with the period of the angle of attack. The drag coefficient of vehicle at various air injection rates increases approximately linearly with the increase in the angle of attack, and the drag reduction rate decreases linearly with the increase in the angle of attack. Key

Key words: underwatervehicle, underwaterdragreduction, pitchingmovement, microbubble, watertunnelexperiment