FDT地层测试器节流控制阀数值模拟

发布时间：2018-02-09 02:51

本文关键词： 节流控制阀计算流体动力学流场结构流量特性阀芯动静态受力数值模拟　出处：《西安石油大学》2011年硕士论文　论文类型：学位论文

【摘要】：电缆地层测试器是通过电缆下放到井下的测试设备。节流控制阀是一种用于地层测试器采样模块系统中控制地层流体流量和压力大小的一种两位两通阀。该节流控制阀相比普通节流阀,体积小,调节精度高,其对压力的有效调节关系到能否采收到地层真实流体。其内部的水力特性是决定节流阀对地层流体样品高效调节的关键因素。同时阀芯在运动过程中,节流阀内部流场特性和阀芯受力是节流阀设计应用中不可忽略的内容。目前,在地层测试器上,节流控制阀的内部流场尚无人研究。为此,本文运用计算流体力学的方法对所设计的节流控制阀模型进行数值模拟,研究阀腔内流场结构和阀芯动静态受力情况。本文根据地层测试器采样模块的相关参数,设计出节流阀,用CAD软件——UG建立节流阀流道的三维模型,并用GAMBIT对模型进行网格划分。通过选用经典的基于压力修正的SIMPLE算法和标准κ-ε两方程湍流模型,分别在静止和运动两种状态下,对节流控制阀内部流场、流量特性和阀芯受力进行数值仿真研究,优化节流阀的设计结构。利用数值模拟,对阀腔内的压力场分布有了清晰的认识：阀腔内的压力在节流口处降低比较明显,低压点出现在阀芯和阀座所形成的间隙内,最低压力值为2.5MPa。远离节流口处的压力比较高。导管处的压力沿径向是降低的,而沿轴向变化不大。通过对节流口速度场内的射流角研究：射流角随着开口度的增大而减小,速度值减小。能量耗散位置处于节流口附近。节流阀的流量随着压力和开度的增大而增大。在一定的开度下,流体的能量耗散和压降成正相关。流量系数与压降没有直接关系,跟节流阀的开度有很大的关系,具体与节流阀本身的结构有关系。通过模拟计算,得到节流阀的流量特性曲线,本阀属于快开特性。在上述节流阀模拟的基础上,提出节流阀结构改进措施。优化结果表明：改进的节流阀结构流场分布更为均匀,在阀口和导管处的漩涡区几乎消除,流体主流在壁面发生分离程度减小,运动方向和流道的方向近乎切合,局部阻力较小。流体能量耗散减小了30%,流量系数提高了25%。运用动网格技术对节流控制阀的受力进行了分析。在稳态受力研究中,作者推导了节流控制阀理论稳态液动力计算式,并与数值模拟结果对比,误差在5%以内,证明数值模拟的结果是可以接受的；节流阀的稳态液动力随着节流阀的开度增大而减小,其方向和阀芯关闭的方向一致。节流阀阀芯在启闭两个过程中,瞬态液动力的变化规律是不一样的。在阀开启时,瞬态液动力变化拐点随阀芯移动速度增大而靠前,力的数值也随着增大。瞬态液动力从负值范围先减小,后跨过零点从正值范围增大。当阀芯移动速度大于1mm/s时,液动力数值很大,且只在负值范围减小；在阀关闭时,瞬态液动力变化拐点随移动速度的增大而靠前,力的数值也随着增大。瞬态液动力仅从正值范围不断减小。当阀芯移动速度过大时,液动力数值也是相当大。通过对节流控制阀内部流场结构和阀芯受力分析,以此为依据,将会对阀优化设计有一定的理论指导作用。
[Abstract]:The invention relates to a cable formation tester , which is a test equipment which is put underground under a cable , and the throttling control valve is a two - position two - way valve for controlling the flow and the pressure of the formation fluid in the sampling module system of the formation tester . Compared with the conventional throttle valve , the throttle control valve is small in volume and high in regulation precision , and the effective regulation of the pressure is a key factor for determining the effective regulation of the fluid sample of the formation . In this paper , according to the relevant parameters of the sampling module of the formation tester , the throttle valve is designed , the three - dimensional model of the throttle flow passage is established by using the CAD software _ UG , and the mesh division is carried out by using the GAMMA - BIT model . By selecting the classical pressure - corrected SIMPLE algorithm and the standard - k - 蔚 two - equation turbulence model , the internal flow field , the flow characteristic and the force of the valve core are simulated numerically under both static and motion states respectively , and the design structure of the throttle valve is optimized . With the numerical simulation , the pressure field distribution in the valve cavity is clearly recognized : the pressure in the valve cavity is reduced obviously at the orifice , the low pressure point appears in the gap formed by the valve core and the valve seat , and the lowest pressure value is 2.5 MPa . The pressure at the conduit is higher than the pressure at the orifice , and the pressure at the conduit is reduced in the radial direction , and the axial change is not large . The flow coefficient and pressure drop have no direct relation , the flow coefficient and pressure drop have no direct relation , the flow coefficient and pressure drop have no direct relation , and the flow coefficient and pressure drop have a great relationship with the throttle valve , and the flow characteristic curve of the throttle valve is obtained through the simulation calculation . On the basis of the above - mentioned throttle valve simulation , the improvement measures of the throttle structure are put forward . The optimization results show that the flow field distribution of the improved throttle valve structure is more uniform , the vortex area at the valve port and the conduit is almost eliminated , the flow direction of the fluid is close to the direction of the flow channel , the local resistance is small , the dissipation of the fluid energy is reduced by 30 % , and the flow coefficient is increased by 25 % . In the study of steady state stress , the steady - state hydraulic power of the throttle control valve is calculated and compared with the numerical simulation results . The results of the numerical simulation show that the results of the numerical simulation are different . When the valve is opened , the dynamic change of the transient liquid decreases with the increase of the opening degree of the throttle valve . By analyzing the internal flow field structure and the force of the valve core in the throttle control valve , this paper will give some theoretical guidance to the optimization design of the valve .

【学位授予单位】：西安石油大学
【学位级别】：硕士
【学位授予年份】：2011
【分类号】：TH137.52

【引证文献】