噴流と円柱の相互作用によって発生する音 : 円柱直径と音の関係

抄録

Sound generated by a two dimensional jet impinging on a circular cylinder was studied by systematically changing its diameter. Frequency of the sound decreases in a step-like manner with an increasing distance x_e between the nozzle and the leading edge of the cylinder. The frequency normalized by U_o/x_e, U_o being the exit velocity of the jet, is a unique function of the non-dimensional distance x_e/H, H being height of the nozzle. This is similar to the case of the jet-wedge interaction. The diameter of the cylinder determines both the longitudinal position of the frequency jumps and the position where the intensity of the sound attains a maximum. The highest intensity of the sound appears when its frequency is the exactly the same as the frequency of the vortex shed from the circular cylinder which would be placed in the uniform stream whose velocity is equal to the undisturbed jet velocity at the leading edge of the cylinder.