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本文討論二維模型試驗所用的二种振源:扩张中心型的振源和垂直集中力型的振源。扩张中心型的振源系用压电钛酸鋇短柱体的径向伸縮,以柱面为发射面而得到的。实驗証明,柱面上的伸縮主要是由直径决定的单頻振动。因此,用寬度相应于径向振动周期的矩形电脉冲来激发晶体时,可以消除由晶体自由振动所造成的“余震”,从而得到短暫的声脉冲。单力型振源是一个用钛酸鋇晶体和黄銅棒制成的杆状发射器。这种发射器在工作頻率范围內,实际上是一个非周期性器件,因此不存在器件的自由振动問題。在实驗中研究了三种不同直径杆状发射器的发射强度与波形同发射方向角间的关系。
This article discusses two sources of vibration used in two-dimensional model tests: the center of expansion and the source of vertical focus. Expansion of the center-type vibrating source system using piezoelectric short bar of titanium dioxide telescopic expansion, with cylindrical surface for the launch. Experiments show that the telescopic cylinder is mainly determined by the diameter of single-frequency vibration. Therefore, when the crystal is excited by a rectangular electric pulse having a width corresponding to the period of the radial vibration, the “aftershock” caused by the free vibration of the crystal can be eliminated and a brief acoustic pulse can be obtained. The single-force vibrator is a rod-shaped emitter made of barium titanate crystals and brass rods. This transmitter is actually an aperiodic device in the operating frequency range, so there is no problem with the free vibration of the device. In the experiment, we studied the relationship between the emission intensity of the three different diameter rod launchers and the direction of the radiation.