管道内流场结构特性是影响自驱钻头自进力和解堵除垢能力的关键因素。针对多股射流共同作用下管道内流场变化影响自进力和返水阻力的问题，基于FLUENT数值分析不同条件下管道内流场变化，得到后置喷嘴角度、转速、环空比和系统压力对自进力的影响规律，揭示综合摩擦因素理论值存在误差的原因，通过正交数值模拟明确自进力影响因素的主次关系。基于自进力测试实验装置，开展不同条件下自进力测试实验，验证数值模拟结果的正确性。结果表明：涡旋挤压碰撞作用和射流卷吸作用导致自驱钻头前后产生压力梯度，从而提高自进力。后置喷嘴倾角由20°增加至45°，壁面射流逆流速度由6.2 m/s增加至14.5 m/s，涡旋碰撞挤压后压力峰值由68.47 kPa增加至80.79 kPa，导致压差力增大。提高转速能够减小一次涡旋范围，当涡旋在旋转体区域发生碰撞挤压时，旋转体所受压差力增加。提高转速、系统压力或减小环空比均会增强后置射流的封隔作用，从而提高自进力。由于理论计算返水阻力时忽略了涡旋区的影响，因此综合摩擦因数理论值需要修正。环空比、系统压力、转速和后置喷嘴倾角的极差分别为300.07、111.87、60.42、36.32，影响因素主次关系为：环空比>系统压力>转速>后置喷嘴倾角。本研究可为自驱钻头结构优化设计、提高自驱钻头的自进力提供参考。

The structural characteristics of inner flow field in a pipeline are the key factors influencing the self-propelling capacity and descaling-unblocking capability of the self-propelled drill bit. To address the problem concerning the effect of the changes in the inner flow field of a pipeline under the joint action of multiple jets on the self-propelling force and the resistance to water backflow, the changes of inner flow field in the pipeline under different conditions were numerically analyzed based on FLUENT, and thus the influence law of the angle of rear nozzle, the rotational speed, the annular ratio and the system pressure on the self-propelling force was defined, revealing the reasons for the error of the theoretical value of the integrated friction coefficient. Besides, the primary and secondary relationships of the factors influencing the self-propelling force were clarified through orthogonal numerical simulations. Then, the self-propelling force testing experiments were carried out under different conditions with the self-propelling force test device to verify the correctness of the numerical simulation results. As shown by the results, the action of vortex squeeze collision and jet suction leads to a pressure gradient in front of and behind the self-propelled drill bits, thus increasing the self-propelling force. The angle of the rear nozzle is increased from 20° to 45°, the countercurrent velocity of wall jet is increased from 6.2 m/s to 14.5 m/s and the peak pressure after vortex collision extrusion is increased from 68.47 kPa to 80.79 kPa, resulting in an increase in differential pressure. Increasing the rotational speed could reduce the range of primary vortex, while the differential pressure applied on the rotating body increases during the collision and squeeze of vortex in the rotating body area. Increasing the rotational speed and the system pressure, or reducing the annular ratio, will increase the isolation effect of the rear jet, thus increasing the self-propelling force. The theoretical value of the integrated friction coefficient needs to be corrected as the effect of the vortex zone is ignored in the theoretical calculation of the resistance to water backflow. The extreme differences of the annular ratio, system pressure, rotational speed and angle of the rear nozzle are 300.07, 111.87, 60.42 and 36.32 respectively, and the main relationships of the influencing factors are: annular ratio > system pressure > rotational speed > angle of the rear nozzle. Generally, the research in this paper could provide a reference for the optimization design in structure and the improvement of self-propelling capacity of the self-propelled drill bits.