Abstract
The self-excitation possibility of underwater organ pipes as the counterpart of aerial ones is considered. Despite of the great differences between water and air, the organ pipe sounds in water as well as in air. The water-jet velocity is formulated by assuming the turbulent jet with weak additional decay. The velocity of the underwater sound propagating in the pipe is theoretically estimated, and the Q-value of the pipe is measured. They depend on the distensibility of the pipe wall material. The margin of selfexcitation is sufficient in aluminium pipes but bare in acryl pipes due to the smallness of Q-value. Numerical calculation well explains the unique experimental excitation characteristics not obtained from aerial organ pipes. Moreover, the overall efficiency of power conversion is estimated.
