高压水射流与多刀具耦合破岩系统的动力学特性研究

Aimming at improving the efficiency of breaking hard coal & rock for excavating equipments and reducing the impact and wear for the broken rock system, the dynamic research on the coupling broken rock system with high-pressure water-jet and multi-cutter will be carried out according to the theories and methods of fluid mechanics, fracture mechanics and discrete element method. Based on the established elastoplastic-brittle model of coal & rock and the grasped kinetic and dynamic characteristics of excavating equipment working mechanisms when crushing different coal&rock, the surface damage model of hard coal-rock by water jet, the coupling broken rock mechanism model of single cutter assisted by water-jet, the self-starting mechanism model of rock broken with self-controlled hydro-cutter, the fatigue stress model of self-controlled hydro-cutter and the coupled broken rock dynamic model of multi-cutter assisted by water-jet will be established by making use of the characteristics of high pressure water-jet(high speed, low temperature), and considering the alternating change between tool thermal stress and mechanical stress in the rock breaking progress by the coupling broken system with the impact of water jet and the milling of cutter. The change regularity of the assisted pressure and position of water jet, and the nozzle diameter, the load characteristics of self-controlled cutter in different conditions will be analyzed, to grasp the main factors influencing the stress state and wearing forms of cutters in different conditions, and the methods for improving the cutter performances are provided; and grasping the optimal arrangement of the multi-cutter broken rock system assisted by water-jet to improve the reliability of the excavating equipment when breaking hard coal&rock.

本项目以提高采掘装备破碎坚硬煤岩效率、降低破岩系统冲击和磨损为研究目标，运用流体力学、断裂力学、离散元法等理论和方法，开展高压水射流与多刀具耦合破岩系统的动力学特性研究。在建立煤岩弹塑脆性模型、掌握采掘装备工作机构破碎不同煤岩特性时的运动和动力学特性基础上，利用高压水射流高速、低温冲击高效破岩的特点，考虑水射流冲击和刀具铣削耦合破岩时影响刀具热应力、机械应力交替变化的因素，研究水射流破碎坚硬煤岩的表面损伤形式，建立水射流辅助单个刀具耦合破岩力学模型、自控水力刀具破岩自开启力学模型、自控水力刀具的疲劳应力模型和水射流辅助多个刀具耦合破岩的动力学模型，分析不同条件下辅助水射流压力、位置、喷嘴直径等参数的变化规律和自控刀具的负载特性，掌握不同条件下刀具受力状态、磨损形式与煤岩特性关系，提出改进刀具性能的措施；获得水射流辅助多个刀具破岩系统的最佳配置形式，提高采掘装备开采坚硬煤岩的可靠性。

针对坚硬煤岩对采掘装备工作机构冲击、磨损严重的问题，利用高压水射流高速、低温冲击高效破岩的特点，考虑水射流冲击和刀具铣削耦合破岩时刀具热应力、机械应力交替变化的条件，基于流体力学、断裂力学、离散元法等理论和方法，建立了水射流破碎坚硬煤岩的表面损伤模型、水射流辅助单个刀具耦合破岩力学模型、自控水力刀具破岩自开启力学模型、水射流辅助多个刀具耦合破岩的动力学模型，以降低刀具磨损量、刀具应力、截割比能耗、粉尘量和提高系统破岩效率、煤岩破碎块度为目标，深入开展水射流高速冲击和多刀具铣削耦合破岩机理研究。结果表明，最佳配置方式为中心射流-截齿，其次是后置式射流-截齿破岩，辅助效果最差的是侧置式射流-截齿破岩，中心射流-截齿受力减小率最大，最大为30.96%，其次是后置式射流-截齿，最大为28.96%，第三是前置式射流-截齿28.17%，射流辅助效果最差的是侧置式射流-截齿，最大为25.42%，射流压力超过岩石抗压强度时，截齿受力减小率有明显的提升，水射流入射角为60°~90°时，具有较好的辅助截齿破岩效果；当自控水力截齿阻尼孔直径为0.25mm时，自控水力截齿与普通水力截齿流量对比约为0.2，能够有效解决水量浪费问题；当无因次靶距x1/d<10，水射流轴向速度只包括核心区和撞击区，水射流动能到压力能转换效率较高；当无因次靶距x1/d<5，无因次冲击压力峰值为1，水射流能量损失几乎为零，能够充分发挥水射流的破碎作用；在压力为22 MPa水射流辅助作用下，水射流截割头I截割扭矩平均降低约30 %，推进阻力平均降低约30 %，截割头旋转截割比能耗、钻进切削比能耗及破岩比能耗平均降低约35 %。水射流截割头II扭矩平均降低约5.5 %，推进阻力平均降低约2.2 %，比能耗平均降低约9 %。水射流截割头III扭矩平均降低约22 %，推进阻力平均降低约25.5 %，截割头比能耗平均降低约27.5 %，与水射流截割头II相比该种水射流辅助破岩效果较好。