超临界二氧化碳(SC-CO₂)射流在钻井工程中具有广泛应用前景，并且其破煤压力阈值低、效率高，能够提高钻井效率。但因其较高的破煤门限压力和系统能耗，限制了其推广应用。自激振荡脉冲SC-CO₂射流的高脉冲压力和谐振效应可有效降低破煤门限压力，显著提高破煤效率。基于此，开展了自激振荡脉冲SC-CO₂射流脉冲频率和脉冲压力幅值对谐振破煤的综合作用研究。采用大涡模拟分析了射流流场结构，明确了流场轴向上脉冲频率和脉冲压力幅值的变化规律；通过脉冲特征测试实验研究了靶距对射流冲击频率和冲击压力的影响，并通过冲击破煤实验研究了脉冲特征对破煤的综合影响，得到了以下结论：自激振荡脉冲SC-CO₂射流脉冲频率和压力幅值在射流轴向处并不会保持不变，随着靶距的不断增大均呈现逐渐减小的趋势。仅考虑脉冲频率并不能将谐振效应最大化，需要综合考虑脉冲频率和压力幅值对谐振效应的影响。采用位移响应振幅表征谐振效果，能够反映频率和幅值对谐振的综合影响。靶距较小时，即0～15 mm，位移响应振幅的主要影响因素为脉冲压力幅值；靶距较大时，即15～30 mm，其主要影响因素转变为脉冲频率。减小脉冲频率并增加压力幅值能够有效提高位移响应振幅。不同喷嘴结构条件下，位移响应振幅主要影响因素的转变位置不同，同时最优靶距也并不相同。该研究中，喷嘴a的最优靶距是22 mm，此处的位移响应振幅最大，破煤效果最好，而喷嘴b的最优靶距是26 mm。

The supercritical carbon dioxide (SC-CO₂) jet has a wide application prospect in drilling engineering, and its low coal breaking pressure threshold and high efficiency can improve drilling efficiency. But it has the problems of high coal breaking threshold pressure and system energy consumption, which limits its application. The high pulse pressure and resonance effect of the self-excited oscillation pulse SC-CO₂ jet can effectively reduce the coal breaking threshold pressure and significantly improve the coal breaking efficiency. Based on this, the variation law and comprehensive effect of the self-oscillating pulse SC-CO₂ jet pulse frequency and pulse pressure amplitude at different target distances were studied. Large eddy simulation was used to analyze the flow field structure of the jet, and the variation laws of the pulse frequency and pressure amplitude in the axial direction of the flow field were clarified. The effect of the target distance on the impact frequency and impact pressure of the jet was studied by pulse characteristics test experiment, and the comprehensive effect of pulse characteristics on coal breaking was studied by coal breaking experiment. It was concluded that the pulse frequency and pulse pressure amplitude of the self-oscillation pulsed SC-CO₂ jet do not remain constant in the axial direction of the jet, and they gradually decrease with the increasing target distance. Considering only the pulse frequency cannot maximize the resonance effect, and it is necessary to comprehensively consider the influence of pulse frequency and pressure amplitude on the resonance effect. Using displacement response amplitude to characterize resonance effect can reflect the comprehensive influence of frequency and amplitude on resonance. When the target distance is small, from 0 mm to 15 mm, the main influencing factor of the displacement response amplitude is the pulse pressure amplitude. When the target distance is large, from 15 mm to 30 mm, the main influencing factor is pulse frequency. In addition, reducing the pulse frequency and increasing the pressure amplitude can effectively improve the displacement response amplitude. The transition positions of the main influencing factors of displacement response amplitude under different nozzle structure conditions are different, and the optimal target distance is also not the same. In this study, the optimal target distance for nozzle a is 22 mm, where the displacement response amplitude is the largest and the coal breaking effect is the best, while the optimal target distance for nozzle b is 26 mm.