Design And Research On Overload Protection Device Of Fluidic Hammer With High Impact Energy

As a kind of green and renewable energy,geothermal power technology is not limited by seasons and climate,and can greatly reduce the greenhouse effect and the impact of acid rain on the environment.In addition,its power generation cost is only10%of solar power generation,and only half of wind power.The reserves are considerable.Only 2%of the hot dry rock resource reserves in the crust can produce2×10³⁸J of energy.Hot dry rock is usually buried deep below 3 km to 10 km on the surface,so the rock has a high close hardness and poor drillability,and the temperature is usually between 200°C and 600°C.As a result,the low drilling efficiency and long drilling cycle in the process of drilling make the high drilling cost a difficult problem in the world.DTH hammer drilling technology has broad application prospects in hot dry rock.At present,compare with the more developed Pneumatic DTH hammer,whose drilling technology is much more advanced than that of the conventional fluidic DTH hammer,and the crushing rock efficiency is higher.On the other hand,due to the incompressibility of the driving medium,the fluidic hammer is less affected by the confining pressure in the deep well,which makes the universities and research institutes and drilling tools research design high-energy fluidic hammers.Despite some progress,there have been no widely used products in the market so far.In the face of the urgent demand for high-energy fluidic hammer in hot dry rock drilling.Designing overload protection device of fluidic hammer with high impact energy,and completes the protection through numerical analysis.The work performance of the prototype was verified by bench tests.The contents of research and main conclusions were presented as follows:?1?Considering the problem that the single impact energy of conventional fluidic hammer is low.Analyzing the current research status of liquid hammer in the market,putting forward some problems,and summarizing the research purpose and research plan of this study.?2?In order to solve the problem that the cemented carbide jet element in the SC86H high-energy fluidic hammer is brittle,it is easy to break when subjected to a large impact load.Study and design the structure of the impact stress wave in the jet-type hydraulic hammer propagation path.Based on the Ansys/Ls-dyna display dynamics analysis method,the joint and impact of the piston rod-flush system impact during the return stroke of the hydraulic hammer.Two different models of the cylinder were simulated to investigate the changes in the stress propagation path and the magnitude of the impact stress experienced by the jet element in two different models.?3?According to the theory of fluid mechanics combined with simulation technology,the safety valve device is designed to prevent the excessive jet flow from entering the working structure of the DTH hammer.A three-dimensional model of the internal flow field of the safety valve is established.The internal flow field model is divided into finite element meshes by hypermesh.Then the relevant simulation parameters are set in Fluent,and the obtained simulation results are used to determine the size parameters of the safety valve.?4?Carry out the bench verification test of the middle joint and the safety valve respectively,verify the protection effect of the joint on the jet element,ensure that the safety valve does not affect the working performance of the fluidic hammer and protect the internal structure of the DTH hammer in time when the overload is working.