| Based on the one-dimensional heat diffusion equation, through numerical simulation with Simulink, the diffusing characteristics of pulsating negative pressure is calculated between bottomhole and cutting layer in different formations. It can be concluded that the suitable suction pulse parameters are: rectangular wave, the vibration frequency is 50 to 100 Hz, the hold time of negative pressure is one to two seconds. This conclusion provides theoretical foundation in the research of pulse jet modulation. Change structural parameters of newly designed flow channel to optimize the channel matching with suction pulse system. It is found that pulse amplitude at downstream of the nozzles changes with different structural parameters. Lab pressure drilling tests were carried out with self-vibration valve type generator and micro-bit. The experimental results show that the rate of penetration declines as the pulse amplitude decreases. Also the studies prove that the promising jet can increase the rate of penetration in lab pressure drilling tests, which guarantee its large application fields.
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