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从钻井泵经过钻柱内部输送到钻头喷嘴的流体是瞬态流动，存在着压力行波，使从普通喷嘴射出的流体有一定程度的脉动。当这种流体经过自激振荡喷嘴轴对称空腔后，初始振荡的频率与腔内扰动波的频率相接近时，整个流体的振荡被迭加、放大，最后在腔室出口处产生被调制了的振荡射流。文章按波动理论原理，建立自激振荡射流腔室内流体压力和速度的数学模型，并采用接近钻头实际喷嘴直径和增大喷嘴金尺寸，进行扩大振荡腔室的射流实验研究。

EXPERIMENTAL RESEARCH ON AUTOEXCITATION JET FLOW AND A DISCUSSION ON FLOWING MATHEMATICAL MODEL IN OSCILLATION CAVITY

Fluid is conveied to bit nozzel through drill string from pump is a transient state flowing with pressure wave, which makes the fluid jetted out from nozzel has certain pulsation. After the fluid passed the axial symmetry cavity of autoexcitation jet nozzel and when initial oscillation frequency approximates to the one of disturbance wave in the cavity, the oscillation of the whole fluid is superposed and amplified. Finally, modulated oscillation jet flow is produced at the cacity exit. In the light of wave theory principle, the mathmatical model of fluid pressure and velocity in the cavity of autoexcitation jet flow is set up and the jet flow experimental research is done by approximating the actural diameter of the nozzel and enlarging the size of nozzel box to widen the oscillation cavity.