超临界二氧化碳射流破岩的热流固耦合机理

Heat-fluid-solid coupling mechanism of supercritical carbon dioxide jet in rock-breaking

针对超临界二氧化碳(SC-CO_(2))射流压力和温差的协同破岩机制,建立了热流固耦合岩石应力计算模型,验证了模型的有效性,研究了SC-CO_(2)、水和氮气射流的流场和岩石应力随喷距的变化。随着喷距增加,SC-CO_(2)射流压力减小,射流温差增大;SC-CO_(2)射流压力高于氮气射流,与水射流相差不大;无因次喷距大于10时,SC-CO_(2)射流温差分别约是水和氮气射流的5倍和2.5倍以上;更大的温度应力是SC-CO_(2)射流破岩效果优于水和氮气射流的主要原因,SC-CO_(2)射流时有更大的岩石应力、有效破岩喷距和破岩面积;喷距较小时SC-CO_(2)射流压力起主要破岩作用,喷距较大时射流温差起主要破岩作用;SC-CO_(2)短时间射流下岩石表面产生拉伸和剪切破坏,长时间射流下岩石内部同时产生大面积的拉伸破坏,SC-CO_(2)射流是一种高效的体积破岩方法。

Aiming at the synergistic rock-breaking mechanism of supercritical carbon dioxide (SC-CO_(2)) jet pressure and temperature difference, a heat-fluid-solid calculation model of rock-breaking stress was established and verified to be effective, and the variations of jet flow field and rock stress with jet standoff distance of SC-CO_(2), water and nitrogen were studied. With the increase of jet standoff distance, the jet pressure of SC-CO_(2) decreases and the jet temperature difference increases. The SC-CO_(2) jet is higher in pressure than the nitrogen jet and differs little from the water jet. Temperature difference of SC-CO_(2) jet is 5 times that of water jet and more than 2.5 times that of nitrogen jet when the jet standoff distance is larger than 10. The temperature stress is the main reason why SC-CO_(2) jet is superior to water and nitrogen jets in rock-breaking. The rock under the SC-CO_(2) jet has greater rock stress, effective rock-breaking jet standoff distance and rock-breaking area. The jet pressure plays a major role in rock-breaking when the jet standoff distance is small, while the jet temperature difference plays a major role in rock-breaking when the jet standoff distance is large. The SC-CO_(2) jet is an efficient volume rock-breaking method, which results in tensile and shear failure on the rock surface under short time jet and large area tensile failure inside the rock simultaneously under long time jet.