【作者】 张彬；

【导师】 甘行平；

【作者基本信息】 中国地质大学（北京） ， 钻井工程， 2011， 博士

【摘要】 气体保护水射流在高压旋喷、石油钻井、清洁行业等越来越多的领域中得到了重视和应用。水气同轴喷嘴的结构选择、在不同淹没环境介质中喷射的流场规律、气体保护提高水射流射流能力的内在机理等对施工工程效益、施工结果具有重要意义。本文研究目的是以高压旋喷中的水气同轴喷嘴为模型,分别在水射流有气体保护和无气体保护的情况下分析了在水、沙质等环境中水射流的流场规律,通过利用CFD流体分析软件进行数值模拟、流动显示试验、施工现场试喷及后期开挖检测,研究水气同轴喷嘴射流对成桩的影响规律,从而为设计结构合理的水气同轴喷嘴及适宜的射流参数提供科学依据。本文所做的主要工作如下:一、分析高压旋喷施工中水气同轴喷嘴结构参数的设置及射流特点。使用欧拉法建立了水气同轴喷嘴内部流场的数学模型,并用标准的两相k ?ε湍流模型模拟两相流场,选取经典的水喷嘴内流道结构,使气环能较好保护水射流且水射流扰动紊乱较小,并对水喷嘴的壁厚以及气喷嘴的流道结构进行了分析。二、将适宜的水气同轴喷嘴组合结构作为数值模拟的分析对象,分别在有、无气体保护水射流,以及水、沙质地层等不同淹没介质环境中,分析了射流各相在流场的不同流向位置处径向剖面以及不同径向位置处流向剖面上的速度、动压等参数变化规律,从而揭示水射流衰减规律。三、根据现场施工的导流器、喷嘴等结构原理,设计出在透明水箱中的流动显示实验装置,分别演示在有、无气环保护下,水射流在空气中以及在水下的流动情况,对射流进行辅助研究。四、利用现场取芯、开挖桩主体及搭接位置段,进行检验、力学测试、压水试验等,证明成桩直径大小的变化规律同数值模拟分析的喷嘴水射流喷射距离远近或射流动压参数衰减快慢的规律总体一致。桩体横截面上颗粒分布状态同喷射淹没环境介质以及距离喷嘴出口的位置范围存在相应的规律。五、通过数值模拟、现场成桩效果的分析,在早期的成桩直径经验公式中考虑进水气同轴喷嘴结构参数、喷射参数等的影响规律,并利用现场结果进行验证。更多还原

【Abstract】 The water jet which is protected by the air is become more and more important and has been widely used in high-pressure jetting ,drilling engineering,washing and cleaning business.Many aspects of the air-water nozzle are very important for the Engineering effect and benefits, such as the optimizations of the air-water coaxial nozzle structures、the regulations of the flow fields which are in different submerged environment、the inner mechanism of how the gas protect water jet to improve the jet ability etc.The purpose of this article is to take the air-water coaxial nozzle in the high pressure jet grouting as a model, respectively analyzing the water jetting with or without the gas protecting circumstances ,and water jetting in different environments,such as water, sandy soil etc, through the methods of using the CFD software to make the numerical simulation、testing in the lab , and later excavation detection in the site to research the laws of the air-water coaxial nozzle how to affect the diameter of the pile, so as to provide the scientific basis for designing the reasonable structures and suitable parameters of the air-water coaxial nozzles. The key work performed in this paper are as follows:Firstly. Analyzing the air-water coaxial nozzle structure parameters and jetting characteristics in the high pressure jet grouting .The euler method is used to establish the internal flow field of the mathematical model for the air-water coaxial nozzle, and the standard two-phase k ?εturbulent model is adopted to simulate the two phase flow field. Selecting the classic water flow structure, with standards of the gas loops can better protecting the water jet and the water jet has less disturbance, making the optimization analysis of the thickness of the water nozzle and gas flow structures .Secondly.Taking the optimal selection of water coaxial nozzle structure as the analysis object for the numerical simulation. Analyzing the flow field rules of the speed、dynamic pressure parameters of each phase ,finding the changes of the phases in the radial profiles situated in different flow positions and flow profiles situated in different radial positions, studying the regulations respectively in the situations of with and without the gas protectiong across the water jet . Revealing the relationship of the water jet decay rate .Thirdly. Designing and manufacturing the devices used in the transparent water tank for the flow showing, demonstrating the jet flow respectively with and without a gas ring protecting the water jet、in the air and underwater for the jet flow qualitative research.Fouthly. Through the core, excavation pile subjects、connecting sections inspections、mechanics and water pressure test etc in the site,all the prooves proved that the pile diameter size consistent with jetting distance or the declay rate of the flow pressure .In the pile cross section, the particles size distribution state exist the corresponding regulations with the jetting submerged environment and the jetting distance from the nozzle.Fifth. According to the numerical simulation and the pile effect analysis, make the improvements about the early pile diameter empirical equation , which has been taken into account the air-water coaxial nozzle structure parameters and the injection parameters aspects, then the pile diameter empirical equation has been verified with the pile inspection in the site.更多还原