中文摘要：

为了揭示直旋混合射流的破岩机理,开展了直射流、旋转射流与直旋混合射流的冲蚀实验,并利用3DPIV测试系统获得了3种射流的速度场,通过对比分析相同靶距下冲孔深度及射流速度沿径向的分布规律,揭示了直旋混合射流的损伤破岩特性。结果表明,直旋混合射流可消除旋转射流的中心低速区和冲孔的中心凸台,该射流沿径向的分布宽度和破岩直径大于直射流,射流结构可分为直射流区、强旋射流区、弱旋射流区和外围射流区。直射流区的冲击破岩能力主要取决于射流能量;强旋射流区具有较大的径向和切向速度,当对岩石施加径向张力和周向剪力且在其合速度小于直射流的情况下,该区破岩深度仍可达到直射流区破岩深度;在弱旋射流区,受直射流和强旋射流的共同作用,岩石强度降低,但当三向速度均较小时亦能有效破岩;外围射流区主要是通过返回流携带岩屑对孔壁起磨削作用。

英文摘要：

To reveal the rock breaking mechanism of straight-swirling integrated jet, the erosion experiments of straight jet, swirling jet and straight-swirling integrated jet were carried out, and the velocity fields of the three jets were obtained by 3DPIV. The damage characteristics of straight-swirling integrated jet were revealed via comparative analyses for distribution laws of hole depth and jet velocity along radial direction at the same target distance. The results show that the straight-swirling integrated jet eliminates the low velocity area and the hole center boss of swirling jet, and both the jet distribution width and hole diameter are bigger than those of straight jet. The jet structure can be divided into straight iet area, high swirl strength jet area, low swirl strength jet area and periphery jet area; the jet energy of straight jet area decides the capacity of rock breaking; high swirl strength jet area has high radial and tangential velocity, thus long depth hole near that by straight jet can be drilled by radial tension and circumferential shearing force under the condition of resultant velocity lower than straight jet; rocks in low swirl strength jet area are damaged by both straight and swirling jets, which decrease the rock strength, and the broken rocks can be transported effectively in this lower velocity area, where rock breaking of periphery jet area results from the wearing of returning jet with rock debris.