滚滑轴承滑块的油-气两相流润滑分析

为改善滚滑轴承的润滑,运用两相流理论对其滑块进行油气润滑设计,建立滑块的油-气两相流CFD模型,分析不同入口角度、进气速度、进油速度和润滑油黏度对流场油相分布的影响。结果表明:油-气混合润滑方式能在内外滚道接触区形成有效的润滑油膜;油气管道夹角影响油滴分布,角度过大时大量油滴会在滑块侧面上附着,角度过小时油滴会在外滚道入口处堆积,造成供油连续性不好,油膜稳定性下降;进气速度过大会降低油滴附着率,无法形成有效油膜,而进油速度过大会造成润滑油累积,出现搅油现象,因此选择合适的进气和进油速度,才能控制油滴的大小和保持润滑过程的连续性;润滑油黏度会影响油滴在滑块上的附着效果,合理地选择润滑油黏度,才能保证流场油相分布均匀。     

水力喷射空气旋流器气相压降特性的数值模拟

利用雷诺应力模型(RSM)的流体体积(VOF)多相流模型对水力喷射空气旋流器(WSA)的气相压降特性和流场进行了数值模拟研究。结果表明,雷诺应力模型和VOF两相流模型能够较好地模拟WSA的气相压降特性和液相回流比,WSA的气相压降随着进口气速的增加先后出现低压降区、压降突跳区和高压降区3个区域。在低压降区,射流保持较好的完整性;压降突跳区,射流呈袋式破碎雾化;高压降区,射流呈剪切破碎雾化。WSA内的静压分布关于Z轴比较对称,整个WSA内在射流—旋流耦合场之上的区域压力最大,其次是WSA的分离空间,在排气管进口区域压力最小。     

Experimental validation of the calculation of phase holdup for an oil–water two-phase vertical flow based on the measurement of pressure drops

The performance of metering the phase holdup of an oil–water two-phase vertical flow has been investigated based on the measurement of the gravity and frictional pressure drops. A U-tube, in which the same flow patterns can be obtained in downward and upward vertical flows, is designed to measure both gravity and fractional pressure drops. During the experiments, the mixture velocities of the oil and water are in the range of 0.28–4.65 m/s and the oil volume fraction from 0 to 1.0. The results show that the oil holdups calculated are satisfactory with the absolute error of ±10%. The method presented in this work can be used to verify the results of tomography due to its simplicity and therefore is sufficient enough to be applied in industry.     

液固两相流压降规律及超声法压降测量

液固两相流广泛存在于能源动力、石油化工等工业过程,两相流压降作为重要的流动参数,有助于流动建模及流态分析。建立液固两相压降测量模型,提出了一种结合超声多普勒及超声透射衰减的液固两相超声压降测量方法。搭建液固两相流动实验平台,对两相压降规律进行研究。两相混合流速和固相体积分数升高时,液固两相压降均逐渐增加。在固相体积分数为0.28%～1.37%,两相混合流速为0.9～1.65 m/s时,根据液固两相压降测量模型及Churchill模型的超声法得到的两相压降与差压传感器测量的压降平均相对误差为4.93%和5.10%,验证了测量模型的准确性。针对非均匀分布的两相流态进行压降测量,进一步拓展了压降测量模型的应用范围。本研究工作为非侵入超声法测量液固两相压降提供了方法基础。     

脱油型静态水力旋流器压力损失测试研究

通过分段测试得到水力旋流器内部各分段压力损失占总压损失的比例情况，同时得到脱油型静态水力旋流器流量、分流比分别与压力、压力损失和压降比的拟合曲线近似呈乘幂关系。通过实验测定与理论分析，发现旋流器有效分离时底流需保持合理的背压，而当溢流压力与底流压力满足适当的比例分配关系时分离效果才较为理想。     

A flow rate measurement method for horizontal oil-gas-water three-phase flows based on Venturi meter,blind tee,and gamma-ray attenuation

Online horizontal oil-gas-water three-phase flow rate monitoring is essential for reliable operations during industrial production. A flow rate measurement method is developed in horizontal oil-gas-water three-phase flows by combining a blind tee, a Venturi meter, and a gamma-ray densitometer. The blind tee is installed at the test section entrance to homogenize the mixture by transforming the horizontal flow to a vertical upward flow. The Venturi meter is used for the total flow rate measurement. The dual-energy gamma-ray densitometer is used for phase holdup measurement. In the present method, blind-tee mixing effects and oil-water mixture slip behavior is essential, which were experimentally analyzed in this work. The phase inversion was found in the oil-water mixture with the increasing of the oil volume fraction. Besides, the addition of the gas reduces the oil-water slip ratio. For the range of 0–35% and 65–100% oil fraction in the oil-water liquid, the oil-water mixture can be well treated as a pseudo homogenous liquid with a slip ratio of 0.9–1.1. A three-phase flow rate model is then established for these conditions. The method was validated by horizontal oil-gas-water three-phase flows with average relative errors of 3.2% for the total flow rates, 4.3% for the gas flow rates, 11.5% for the oil flow rates, and 7.8% for the water flow rates.     

轴入式两级串联旋流器流场分析与性能评估

为解决狭长空间内无法实现油水两相介质高精度分离的问题,结合旋流分离理论,设计了一种可实现轴向进液的两级串联旋流器,针对该装置开展内部流场特性及 分离性能研究。揭示了不同处理量及分流比对旋流器内速度场、压力场、浓度场以及分离效率的影响规律。结果表明：随着处理量的增大,底流口压降最大值逐渐增大且增长速率逐渐增大,旋流腔内切向速度也逐渐增大;增大一级溢流分流比,可减小环式通道及二级旋流器内的切向旋动能,二级溢流分流比对一级旋流器分离性能影响不大;实验及模拟得出研究范围内一级分流比为20%、二级分流比为15%时分离效率最高,最佳处理量为4.8 m3/h,最佳总分流比为32%;装置对不同流量、不同分流比条件具有较强的适应性,分离效率最高可达99.6%。     

Pressure drop of wet gas flow with ultra-low liquid loading through DP meters

The most common method to predict the gas and liquid flow rates in a wet gas flow simultaneously is to use dual pressure drops (dual-DPs) from two or even one single DP meter. In this paper, the metering mechanism of applying dual-DPs were overviewed. To fully understand the response of DP meters to wet gas flows, the pressure drops of wet gas flow with ultra-low liquid loading through three typical DP meters were experimentally investigated, including an orifice plate meter, a cone meter and a Venturi meter. The equivalent diameter ratio is 0.45. The experimental fluids are air and tap water. The pressure is in the range of 0.1–0.3 MPa and the Lockhart-Martinelli parameter (X_LM) is less than approximately 0.02. The results show that the upstream-throat pressure drop, the downstream-throat pressure drop and the permanent pressure loss of individual DP meters have unique response to liquid loading. The upstream-throat pressure drop of the orifice plate meter decreases at first and then increases as the liquid loading increases, while that of the cone meter and the Venturi meter increase monotonically. The non-monotonicity of the pressure drop for the orifice plate meter can be attributed to the flow modulation of trace liquid. The downstream-throat pressure drops of all the three test sections decrease at first and then increase. The reason is that the liquid presence in a gas flow increases the downstream friction and vortex dissipation. The permanent pressure loss of the orifice plate meter also shows non-monotonicity. To avoid non-monotonicity, the pressure loss ratio is introduced, which is defined as the ratio of the permanent pressure loss to the upstream-throat pressure drop. Results show that the pressure loss ratio of the Venturi meter has the highest sensitivity to the liquid loading.     

Flow rate measurement by kinematic wave detection in vertically upward, bubbly two-phase flows

This paper describes a technique for measuring the flow rates of both phases in one-dimensional, vertically upward, bubbly oil–water flows. Measurements of the speed of naturally occurring kinematic waves, obtained using an impedance cross-correlation flow meter, were combined with measurements of the disperse phase volume fraction and an appropriate kinematic wave model to yield predictions of the flux density of both the oil and the water. A systematic error of −3.16%, and an additional random error with a standard deviation of 2.58%, was observed in the predicted oil flux density (and the predicted oil volumetric flow rate). A systematic error of +4.41%, and an additional random error with a standard deviation of 4.83%, was observed in the predicted water flux density (and the predicted water volumetric flow rate). The impedance cross-correlation flow meter has no moving parts and is of robust construction, making the technique described here suitable for implementation in vertical oil wells.     

原油脱水用旋流器两相流场模拟及操作性能和分离性能研究

基于计算流体力学(CFD),采用FLUENT中的欧拉两相流模型对原油脱水用旋流器中的两相流场进行数值模拟研究,并通过试验和模拟研究了它的操作性能和分离性能。结果表明,原油脱水过程中,随着含油量的增大,旋流器内轴向速度变化不大,而切向速度沿轴向衰减严重,有效分离区域缩减,且旋流器内存油增多,中心油柱较明显。进料含油50%时,中心油柱的长度约为旋流器总长度的2/3。随着进料含油量的增加,旋流能量损失增大。原油脱水用旋流器的底流压力降随处理量呈幂函数增大。     

Evaluation of hot-film,dual optical and Pitot tube probes for liquid–liquid two-phase flow measurements

An experimental study of kerosene–water upward two-phase flow in a vertical pipe was carried out using hot-film, dual optical and Pitot tube probes to measure the water, kerosene drops and mixture velocities. Experiments were conducted in a vertical pipe of 77.8 mm inner diameter at 4.2 m from the inlet (L/D=54). The tests were carried out for constant superficial water velocities of 0.29, 0.59 and 0.77 m/s (flow rates = 83, 167 and 220 l/min) and volume fractions of 4.2%, 9.2%, 18.6% and 28.2%. The Fluent 6.3.26 was used to model the single and two-phase flow and to reproduce the results for the experimental study. Two methods were used to evaluate the accuracy of the probes for the measurement of the velocities of water, drops and mixture for two-phase flow: (i) comparison of measured local velocities with predictions from the CFD simulation; (ii) comparison between the area-averaged velocities calculated from the integration of the local measurements of water, drops and mixture velocities and velocities calculated from flow meters’ measurements.The results for single phase flow measured using Pitot tube and hot-film probe agree well with CFD predictions. In the case of two-phase flow, the water and drops velocities were measured by hot-film and dual optical probes respectively. The latter was also used to measure the volume fraction. These three measured parameters were used to calculate the mixture velocity. The Pitot tube was also used to measure the mixture velocity by applying the same principle used for single phase flow velocity. Overall the mixture local velocity measured by Pitot tube and that calculated from hot-film and dual optical probe measurements agreed well with Fluent predictions. The discrepancy between the mixture area-averaged velocity and velocity calculated from flow meters was less than 10% except for one test case. It is concluded that the combined hot-film and optical approach can be used for water and drop velocity measurements with good accuracy for the flow conditions considered in this study. The Pitot tube can also be used for the measurement of mixture velocities for conditions of mixture velocities greater than 0.4 m/s. The small discrepancy between the predictions and experimental data from the present study and literature demonstrated that both instrumentation and CFD simulations have the potential for two-phase flow investigation and industrial applications.     

润滑油对R32在水平光管内流动沸腾换热特性及压降的影响

对R32在φ5mm和φ7mm的水平光管内的流动沸腾时,润滑油对换热与压降特性的影响进行了试验研究,试验的质量流量范围为100~500 kg/(m~2·s),润滑油的含量在0~5%之间。结果表明,沸腾换热系数随着质量流量的增大而增大。在低干度区,换热系数随干度的增大而增大,当干度达到0.7~0.8时,换热系数达到最大。随着润滑油含量的增大,局部换热系数在减小。压降随着管径的减小和质量流量的增大而增大。润滑油含量的增大,导致压降的增大。在5mm管内,润滑油含量对换热系数和压降影响比较明显。     

流体扰动式油-水分离设备研究

阐明了一种新结构重力除油装置,即在流体流动的方向上设置障碍,局部扰动流体的滞流状态,迫使流体内部质点产生位移碰撞,使含油废水中的微小颗粒油滴聚集成较大颗粒油滴,从而增加油滴的上浮速度,同时应用"浅池沉降"理论,将除油装置设计成多层扰动板结构,以减小含油废水在设备中的停留时间。对停留时间、扰动程度、温度对除油效率影响的试验结果进行了理论分析。经模拟试验,该除油装置对3种废水的除油效率约在91%～98%,除油效果好。     

Flow pattern identification and measurement techniques in gas-liquid-liquid three-phase flow: A review

The simultaneous flow of gas, oil, and water forms various flow patterns due to the complex interfacial relationships. Three-phase flow patterns are classified as the gas-liquid and liquid-liquid flow patterns. Pressure drop, void fraction, liquid holdup, and phase distribution are important characteristics of the three-phase flow. These characteristics are generally associated with the three-phase flow patterns. Hence, the knowledge about flow patterns can help to predict the overall behavior of the three-phase flow. Studies have been conducted to identify three-phase flow pattern and their characteristics at various superficial velocities of gas, oil, and water. The major purpose of the studies is to gather information about the three-phase co-current flow and use it for improvement of the efficiency of the flow systems. Therefore, the accuracy of the measurement technique is critical. Several types of flow pattern identification and measurement techniques have been developed to improve accuracy and provide high-quality results. In this article, classical and advanced techniques used for the three-phase flow identification and measurement have been reviewed. The survey will help the researchers working in the area of multiphase flow to choose the right technique based on the objectives of the studies.     

Coriolis mass flow metering for three-phase flow: A case study

Previous work has described the use of Coriolis mass flow metering for two-phase (gas/liquid) flow. As the Coriolis meter provides both mass flow and density measurements, it is possible to resolve the mass flows of the gas and liquid in a two-phase mixture if their respective densities are known. To apply Coriolis metering to a three-phase (oil/water/gas) mixture, an additional measurement is required. In the work described in this paper, a water cut meter is used to indicate what proportion of the liquid flow is water. This provides sufficient information to calculate the mass flows of the water, oil and gas components. This paper is believed to be the first to detail an implementation of three-phase flow metering using Coriolis technology where phase separation is not applied.Trials have taken place at the UK National Flow Standards Laboratory three-phase facility, on a commercial three-phase meter based on the Coriolis meter/ water cut measurement principle. For the 50 mm metering system, the total liquid flow rate ranged from 2.4 kg/s up to 11 kg/s, the water cut ranged from 0% to 100%, and the gas volume fraction (GVF) from 0 to 50%. In a formally observed trial, 75 test points were taken at a temperature of approximately 40 °C and with a skid inlet pressure of approximately 350 kPa. Over 95% of the test results fell within the desired specification, defined as follows: the total (oil+water) liquid mass flow error should fall within ±2.5%, and the gas mass flow error within ±5.0%. The oil mass flow error limit is ±6.0% for water cuts less than 70%, while for water cuts between 70% and 95% the oil mass flow error limit is ±15.0%.These results demonstrate the potential for using Coriolis mass flow metering combined with water cut metering for three-phase (oil/water/gas) measurement.     

High GVF and low pressure gas–liquid two-phase flow measurement based on dual-cone flowmeter

Parameter measurement of gas–liquid two-phase flows with a high gas volume fraction (GVF) has received great attention in the research field of multiphase flow. The cone meter, as a new proposed differential pressure (DP) meter, is increasingly being applied in flowrate measurement of gas–liquid two-phase flow. A dual-parameter measurement method of gas–liquid two-phase flow based on a dual-cone meter is proposed. The two-phase flow is investigated in a horizontal pipeline with high GVF and low pressure, and exists in the form of annular flow. By adding a second cone meter, both gas mass fraction (GMF) and mass flowrate are measured. The pressure drop performances of five different sized cones have been discussed to make a cooperating cone selection and efficiently position the dual-cone in the pipe. Dual-cone flowmeter experiments of 0.45 and 0.65 equivalent diameter ratio combination, and 0.65 and 0.85 equivalent diameter ratio combination are respectively carried out to analyze the linearity of two-phase flow multiplier with Lockhart–Martinelli parameter and obtain the dual-parameter measurement results. The relative experiment error of GMF, gas mass flowrate and total mass flowrate are respectively within ±7%, ±5% and ±10%. The relative error of the liquid phase is within ±10% when the liquid mass fraction is beyond 40%. The experimental results show that it is efficient to utilize this dual-cone method for high GVF and low pressure gas–liquid two-phase flow measurement.     

A study of mass flow rate measurement based on the vortex shedding principle

Mass flow rate measurement is very important in the majority of industry processes because the mass of fluid is not affected by ambient temperature and pressure as the volume will be. Conventional mass flow rate is normally derived from the volumetric flow rate multiplied by fluid density. The density can be obtained by a densitometer or calculated according to the temperature and pressure measured by a thermometer and pressure gauge respectively. However the measurement accuracy is not always satisfactory. Flowmeters directly measuring mass flow rate have been studied and developed recently, such as Coriolis and thermal flowmeters. Unfortunately they still have some limits in practical applications. A new method in which mass flow rate can be directly measured based on the vortex shedding principle is presented in this paper. As a vortex flowmeter, von Kàrmàn vortex shedding is generated by a bluff body (vortex shedder), leading to a pressure drop and pressure fluctuation. A single differential pressure sensor is employed to detect the pressure difference between upstream and downstream sides of the vortex shedder. Both vortex shedding frequency and pressure drop are contained from the output signal of the differential pressure sensor, so that the mass flow rate can be obtained from the pressure signal. Numerical simulation has been done to analyze the characteristics of the fluid field and design the measurement device. The Computational Fluid Dynamics (CFD) codes Fluent were used in the numerical simulation. Experiments were carried out with water and gas, and the results show that this method is feasible and effective to measure the mass flow rate. This method has also robustness to disturbances such as pipe vibration and fluid turbulence.     

叶片式水力旋流器操作参数优选

采用CFD软件中基于各相异性的雷诺应力湍流模型,应用PC-SIMPLEC算法,对叶片式旋流分离器内部流场进行了全面深入的三维数值模拟,得到了旋流器内部流场的压力分布特性和油相体积分数分布特性。通过数值模拟和试验研究,对旋流器的操作参数进行了优化,分析了不同分流比和流量对分离效率的影响,并最终优选出最佳分流比和最佳操作流量。     

Investigation of single phase frictional pressure loss in circular micro tubes

Single phase pressure drops in micro tubes were investigated through an experimental measurement and a numerical simulation. Experimental Po was obtained in circular micro tubes with 87 and 118 μm diameter with distilled water. Experiments were carried out in laminar flow region with varying the Re 15–450 for the 87 μm diameter tubes and 60–1300 for the 118 μm diameter tube. No early transition from laminar to turbulent flow was detected for the experimental range. The computational estimation of pressure drop in the 87 μm diameter tube was performed with the aid of CFD software. Boundary conditions from experiments were used for the numerical simulation. The results of experimental and numerical studies showed a good agreement with the conventional macro theory.     

流体电容仪新的测量模型

本文针对油田生产测井中应用很广泛的流体电容含水率计在理论上和实验上进行了详细的研究。根据现有的实验事实，提出了高含水测量模。该模型认为，对于油水泡状流，即使在水矿化度很高时，流体电容仪仍在０－１００％的含水率范围内有油水分辨能力。