钻井减摩振荡器工作特性研究与试验分析

针对水平井、定向井钻井过程中摩阻大、拖压等问题,提出一种新型振荡器以减小钻柱与井壁之间的摩擦(钻井减摩振荡器)。首先分析减摩振荡器的工作原理,建立其运动学和力学模型,在此基础上,建立试验条件下的振动分析模型。通过算例分析得到过流面积变化频率与流量之间的关系,计算结果表明过流面积随静阀孔直径增大而增大,总轴向力随静阀孔直径增大而减小,与过流面积成反比。对静阀孔直径为27.94 mm的减摩振荡器进行试验测试,通过分析试验测试与理论计算结果的关系,验证了研究方法的正确性。研究成果可为新条件下的钻井减摩降阻、提高机械钻速的相关技术与工具研究提供参考。     

钻柱振动作用下的定向井井眼轨迹分析模型

针对定向井井眼轨迹研究现状和横向振动对钻柱受力影响,进行了钻柱振动作用下的定向井井眼轨迹分析。首先,结合定向井钻井过程,建立钻柱横向振动模型,在此基础上,得到钻柱振动下定向井井眼轨迹分析模型,以及钻头侧向力和钻头转角的关系式。然后,利用钻井现场的有关参数,结合算例分析分析,验证计算方法和分析模型的可靠性。研究结果表明:钻柱中点处横向位移、钻柱与井壁的接触力、钻头侧向力和钻头偏移角有着密切的联系,它们有着相同的变化周期。当钻柱中点处横向位移处于正方向最大值时,钻头转角达到正方向最大值,而钻柱与井壁的接触力、钻头侧向力达到负方向最大值。     

水力振荡器关键力学参数变化规律的研究

为了解决水平井、大位移井等复杂井钻进过程中出现的大摩阻、钻压拖拽等问题,设计了一种新型水力振荡器。根据水力振荡器的内部结构和工作特性,结合流体力学原理,对水力振荡器过流面积、压降、总轴向力关键力学参数的变化规律进行理论分析。选取某一规格水力振荡器的不同静阀孔径进行算例分析,结果表明在水力振荡器输入流量和入口压力一定时,静阀孔径大小与过流面积呈正比,与压降、总的轴向力呈反比;此外,通过改变流量至25L/s,进一步分析水力振荡器关键参数的变化规律。研究结论可为水力振荡器轴向振动分析提供理论支撑,为实现水力振荡器减摩降阻的功能提供技术指导。     

水力振荡器振动特性分析

针对大位移井和水平井钻柱与井壁摩阻大的问题,提出一种具有轴向振动减摩作用的水力振荡器。在水力振荡器结构设计、工作原理分析的基础上,建立其运动方程和力学特征模型,确定马达转子和动阀板运动关系,进行马达转子和阀片部分的受力分析,并建立水力振荡器在水平井的振动方程。通过算例分析得到过流面积变化频率与流量成正比,过流面积随静阀孔直径增大而增大,总轴向力随静阀孔直径增大而减小,振动位移随静阀孔直径、安装位置和井壁摩擦系数的增大而减小。现场试验表明,水力振荡器的使用可以减小井壁摩擦,改善钻压传递,钻井提速效果明显。     

压力脉动对气体钻井钻杆振动特性的影响

基于钻杆振动的现有研究情况,以及压力脉动对气体钻井钻杆振动的重要影响,本文提出考虑压力脉动的气体钻柱振动特性计算方法。首先根据气体钻井实际情况,分析其压力脉动特性;然后建立包含压力脉动的激振力计算方法,在此基础上,建立钻杆振动特性计算模型。根据建立的模型,结合算例参数,分析了气体钻井钻杆的振动特性,包括压力脉动、激振力、弯头角度、模态阶数、振动位移及速度等。并通过对比实验测试与算例计算的结果,验证了分析方法与计算模型的可靠性。研究结果表明:压力脉动对气体钻井钻杆振动具有重要影响,进行气体钻井钻杆振动特性研究,需要基于压力脉动计算模型,建立激振力求解方法,才能保证钻杆振动特性分析的准确性、可靠性。研究结论对于气体钻井钻杆失效机理、钻杆共振特性以及提高钻杆使用寿命具有参考意义。     

考虑钻头-岩石非线性相互作用的钻柱动力学研究

钻头作为底部钻具组合的重要组成部分,直接与岩石接触,其动态特性对底部钻具组合有重要影响。提出了聚晶金刚石钻头（PDC钻头）与岩石的非线性相互作用模型,采用PDC钻头动态特性作为钻柱动态模型的边界条件。为了更真实地模拟钻柱动力学,基于哈密顿原理,采用梁有限元法建立了钻柱动力学模型,通过广义-α法求解,并分析了PDC钻头的动态特性。研究结果表明：轴向振动是钻头最剧烈的振动形式,而当轴向振动传递到钻柱时,产生大幅度衰减,横向振动成为钻柱的主要振动;中性点附近的钻柱不再与井筒碰撞,其运动轨迹接近井眼轴线。     

钻柱横向非线性振动分析

利用同伦分析法求解了钻柱横向非线性振动方程,得到了该非线性振动的频率和主振动的一阶近似解析解.分析过程中发现,同伦分析法在求解钻柱横向非线性振动方程时不需要引入以往摄动求解的小参数,这样提高了近似解的精度和扩大了解的适用范围.计算结果表明非线性因素改变了主振动的形态,使其不再成为简谐振动,同时非线性因素对频率的影响程度随着振幅、轴向压力和钻柱长度的增大而增加.因此,对于受较大轴向压力作用的长钻柱横向振动,应当考虑非线性因素的影响.     

广义边界下含双相流水平井钻柱频率特性分析

钻柱在内流作用和旋转因素的影响下容易产生耦合振动,发生疲劳失效。本文基于微分求积法（DQM）对含双相流水平井钻柱耦合动力学特性进行了研究。利用扩展的Hamilton变分原理建立了计入内流、轴向压力及旋转等因素影响的水平井钻柱动力学方程。在振动问题中考虑了广义边界条件,通过改变边界等效弹簧刚度将模型简化为简支、悬臂等简单边界条件模型进行研究。通过分析旋转角速度、轴向压力、液相流速、气体体积分数等因素对模型频率特性的影响,得到了无量纲固有频率随不同参数变化的特征曲线。分析结果表明：不同边界条件下模型的频率特性曲线有很大的差别;气体体积分数对临界流速的影响在悬臂管系统中表现的更为明显;在简支管模型中,随着轴力的增大会产生模态耦合颤振。此外,通过液相流速和旋转角速度的频率云图展示了两种因素对钻柱频率特性的影响。     

轴向载荷作用下细长柔性旋转梁横向振动响应分析

将水平井柔性钻柱简化为轴向载荷作用下的细长柔性梁,建立了考虑几何大变形的非线性动力学方程,并且利用多重尺度法得到了柔性梁横向振动的平均方程。因钻柱转速和轴向力是影响钻柱振动的两个主要参数,故用改变转速的方法来对平均方程进行非线性动力学响应分析,给出了一阶、二阶模态下钻柱随转速变化的分叉图和不同转速下的相图。分析结果表明,系统响应经历了从周期到混沌再到二倍周期的变化过程,振动幅值有跳变现象出现,在共振条件下,柔性旋转梁振动幅值是有限值,并非无穷大,当轴向力发生变化时,可以通过控制转速变化达到定性、定量地控制柔性钻柱横向振动的目的。     

基于ANSYS的钻柱振动规律分析

根据牙轮钻头与井底岩石互相作用的特点,将钻柱视为一连续的管梁结构,采用ANSYS工程软件,对钻柱纵向振动规律进行了分析。结果表明:钻柱系统各阶振动固有频率相差约1Hz左右,容易出现共振。高频振动时,钻柱出现"分段振动"的特点,下部钻铤动态力显著增加;转盘转速对钻柱振动的影响较大,当接近共振点时,下部钻铤螺纹联接处动态力呈数量级增加;钻压对钻柱振型、轴向动态力的影响不大。     

Vibration analysis of new drill string system with hydro-oscillator in horizontal well

With the growth of oil and gas resource demand, the hydro-oscillator is widely used to enhance the Rate of penetration (ROP) and improve the efficacy in drilling various wells. The vibration model is the key issue of dynamics analysis and optimization of downhole tools. For the vibration analysis of the new drill string system with hydro-oscillator in the horizontal well, based on the design of the new hydro- oscillator and its operation conditions, the kinematics expressions are presented. Combined with the vibration force calculation results of the hydro-oscillator, the dynamics model of the new drill string system is established. Furthermore, the important features of vibration frequency, displacement, velocity and acceleration are discussed in the numerical example calculation results. By comparing the results of the calculation and experiment test, we can verify the correctness of the analysis model. With the hydro-oscillator vibration effect, the static friction between the drill string and wellbore is changed to the dynamic friction, so it can result in a significant increase in run length. At the same time, the ROP can be enhanced with the vibration effect. Moreover, with the parameters’ adjustment according to the operation conditions, the analysis method and model can also provide references to the study of similar downhole tools dynamics or mechanical properties.     

基于摩擦耗能原理的抑振镗杆

讨论了摩擦耗能镗杆的原理,建立了有非线性库仑干摩擦环节的力学模型,并以摩擦参数为变化量,通过数值分析的方法考察了模型的吸振效果。研制了一种基于摩擦减振的新型镗杆,结合颤振发生的机理与切削稳定性理论,分析了不同摩擦条件下镗杆的抑振效果。将不同摩擦条件下的镗杆切削实验结果与理论模型仿真结果进行对比,发现在既定的摩擦阻尼器中,有滑动摩擦与粘接两个状态,而且存在一个最优正压力使得滑动摩擦消耗能量达到最大值又不处于粘接的状态,此时系统抑振效果达到最佳。切削实验发现基于摩擦减振原理的镗杆有良好的颤振抑制效果。      

Stochastic modeling of friction force and vibration analysis of a mechanical system using the model

The squeal noise generated from a disk brake or chatter occurred in a machine tool primarily results from friction-induced vibration. Since friction-induced vibration is usually accompanied by abrasion and lifespan reduction of mechanical parts, it is necessary to develop a reliable analysis model by which friction-induced vibration phenomena can be accurately analyzed. The original Coulomb’s friction model or the modified Coulomb friction model employed in most commercial programs employs deterministic friction coefficients. However, observing friction phenomena between two contact surfaces, one may observe that friction coefficients keep changing due to the unevenness of contact surface, temperature, lubrication and humidity. Therefore, in this study, friction coefficients are modeled as random parameters that keep changing during the motion of a mechanical system undergoing friction force. The integrity of the proposed stochastic friction model was validated by comparing the analysis results obtained by the proposed model with experimental results.     

非接触机械密封的非线性动特性系数及瞬态振动响应分析

建立了考虑倾斜情况的弹性补偿单元支撑的非接触机械密封瞬态振动响应分析模型,该模型包括了瞬态Reynolds方程、运动方程以及二阶非线性动特性系数求解方程等。采用Euler法求解获得了非接触机械密封在轴向振动位移和静环倾角随时间变化时的瞬态振动响应特性。计算得到瞬态油膜力作用下的密封轴向力和倾覆力矩相关的14个动特性系数。结果表明：密封间隙内流体阻尼对密封副和摆动的影响是线性的;密封副瞬态振动影响油膜厚度分布,从而引起油膜压力分布发生变化,结果导致密封环发生摆动;密封副摆动同样也会引起密封轴向振动。     

用复合振子模型计算纳米尺度滑动摩擦力的研究

以光滑界面摩擦为研究对象,探讨用复合振子模型计算纳米尺度滑动摩擦力的原理和方法,推导出滑动摩擦力和摩擦因数的计算公式,并用原子力显微镜探针在硅试样和云母试样上做扫描实验进行验证。实验值与理论计算值的对比结果表明,两者所反映的规律基本一致,表明所提出的理论和方法可行。研究表明,滑动摩擦力与接触面积成线性增长关系,并随宏观振子横向刚度的增大而减小,由于可通过改变摩擦表面的几何形貌来改变宏观振子的横向刚度,因此这一结论将为摩擦控制提供一种新途径。     

A phenomenological friction model of tripod constant velocity (CV) joints

Constant velocity (CV) joints have been favored for automotive applications, compared to universal joints, due to their superiority of constant velocity torque transfer and plunging capability. High speed and sport utility vehicles with large joint articulation angles, demand lower plunging friction inside their CV joints to meet noise and vibration requirements, thus requiring a more thorough understanding of their internal friction characteristics. In this paper, a phenomenological CV joint friction model was developed to model the friction behavior of tripod CV joints by using an instrumented CV joint friction apparatus with tripod-type joint assemblies. Experiments were conduced under different operating conditions of oscillatory speeds, CV joint articulation angles, lubrication, and torque. The experimental data and physical parameters were used to develop a physics-based phenomenological CV joint dynamic friction model. It was found that the proposed friction model captures the experimental data well, and the model was used to predict the external generated axial force, which is the main source of force that causes vehicle vibration problems.     

摩擦驱动型压电叠堆直线电机的工作机理

以一种典型的摩擦驱动型压电叠堆直线电机结构为例,对摩擦驱动型压电叠堆直线电机的振动摩擦驱动机理进行研究.结合电机系统的振动脱离模型,分析了电机定子与动子脱离的力学条件,进而分析电机结构参数和工作参数对椭圆运动和振动脱离性能的影响.对原理样机进行了试验研究,结果表明,压电叠堆的激励电压、激励频率和电机的预压力对电机的振动脱离性能有显著影响.     

Stick-slip vibration of a moving oscillator on an axially flexible beam

This study investigates the stick-slip vibration between an axially flexible beam fixed at both ends and an oscillator moving on the beam. After deriving the equations of motion for the stick and slip states, the stick-slip vibrations between the oscillator and the beam are analyzed. In addition, to obtain the irregularly changed contact position due to the axial deformation of the beam and oscillator movement, a mathematical expression for the contact position is derived. It is found that the long-period stick-slip vibration is influenced mainly by the oscillator and the short-period vibration is influenced mainly by axial deformation of the beam. Furthermore, the dynamic responses show that even if a high damping ratio is applied to the oscillator, stick-slip vibration due to axial deformation of the beam can occur. Finally, the analysis shows that a kind of the internal resonance occurs between the oscillator and the beam when the harmonics of the natural frequency of the oscillator match the natural frequencies of the beam.

     

摩擦驱动型压电叠堆直线电机的工作原理

以一种典型的摩擦驱动型压电叠堆直线电机结构为例,对摩擦驱动型压电叠堆直线电机的振动摩擦驱动机理进行研究。结合电机系统的振动脱离模型,分析了电机定子与动子脱离的力学条件,进而分析电机结构参数和工作参数对椭圆运动和振动脱离性能的影响。对原理样机进行了试验研究,结果表明,压电叠堆的激励电压、激励频率和电机的预压力对电机的振动脱离性能有显著影响。     

Prediction of vibration amplitude from machining parameters by response surface methodology in end milling

Decreasing vibration amplitude during end milling process reduces tool wear and improves surface finish. Mathematical model has been developed to predict the acceleration amplitude of vibration in terms of machining parameters such as helix angle of cutting tool, spindle speed, feed rate, and axial and radial depth of cut. Central composite rotatable second-order response surface methodology was employed to create a mathematical model, and the adequacy of the model was verified using analysis of variance. The experiments were conducted on aluminum Al 6063 by high-speed steel end mill cutter, and acceleration amplitude was measured using FFT analyzer. The direct and interaction effect of the machining parameter with vibration amplitude were analyzed, which helped to select process parameter in order to reduce vibration, which ensures quality of milling.