負荷発振現象に関する一考察

抄録

In this study, the authors investigate oscillations occurring in a loaded oscillator with long output channels. A mathematical model for the oscillator (a distributed parameter model) is introduced and analysed by a graphical method. As the results, it is found that a series of oscillations with step-wise wave forms occurs in the oscillator. The oscillation has a rectangular wave form with equal pulse widths when the impedance of the output channel Z is large (or the power jet flow Qs is small), but for the small impedance the wave form becomes step-wise and the number of the step involved in a period increases with a decrease of Z (or an increase of Qs). The oscillation having 2n steps in a period is termed the “oscillation in stage n”, the frequency of which is c/4nL (n=1, 2, 3, …), where c is the velocity of sound and L is the length of the output channels. The condition of occurrence of the oscillation in stage n and the amplitude are investigated analytically.
Furthermore, it is pointed out that two odd types of oscillation can occur when an initial large disturbance is applied to the flow in the output channels. They have wave forms diffrent from the step wise oscillation mentioned above, and have a rectangular wave form with irregular pulse widths which are determined by the initial disturbances. One of the odd oscillations has a frequency c/4L and the other c/2L. The theoretical results are supported experimentally.