螺杆泵转速对油水旋流分离管流场特性的影响

旋流分离器在井下采油螺杆泵作用下会发生复杂的振动现象,对旋流分离器内部流场造成一定影响。为研究螺杆泵不同转速下旋流分离器内部流场的变化规律,以同井注采工艺中螺杆泵作用下的旋流分离管柱为研究对象,针对振动壁面旋流分离管柱结构及工作特点,基于计算流体动力学方法、计算固体力学方法以及流固耦合理论,建立流固耦合力学模型;利用流固耦合分析方法,对双螺杆泵转动条件下井下旋流分离管柱内速度场、油相分布、涡量及湍动能等流场特性进行分析。分析结果表明:随着螺杆泵转速升高,分离器内切向速度和轴向速度强度逐渐减弱,径向速度的不对称性逐渐加剧,转速的周期性变化还会造成径向速度场分布的偏移;螺杆泵不同转速下旋流分离器内部涡量分布不同,随着转速升高,溢流管以及锥段部分附近相关流场的涡旋明显增强;旋流器溢流口附近油相体积分数会随着螺杆泵转速的升高而减小;不同螺杆泵转动状态下,大颗粒油滴的分布不同。所得结果可为螺杆泵井下旋流分离同井注采系统的设计及螺杆泵的转速设定提供参考。

海藻酸钠和低甲氧基果胶抑制油炸甘薯淀粉吸油效果及结构变化

为探明海藻酸钠(sodium alginate,AG)和低甲氧基果胶(low methoxyl pectin,LMP)对油炸甘薯淀粉吸油率的影响,使用低场核磁共振仪、激光共聚焦显微镜、X射线衍射仪、红外光谱及差示扫描量热仪分别分析了添加0.5%(w/w)、2%(w/w)AG和2%(w/w)LMP的油炸甘薯淀粉的油含量及其分布、热性质等。结果表明,添加AG或LMP可以显著降低油炸甘薯淀粉总油含量,油主要分布在淀粉颗粒表层,淀粉结晶类型由A+V型变为V型,糊化焓和相对结晶度明显降低。与添加LMP的油炸甘薯淀粉相比,添加AG后总油含量、相对结晶度和糊化焓更低。添加AG质量分数为2%时,油炸甘薯淀粉糊化程度最高,淀粉颗粒表层呈连续、致密结构,总油含量和表层油含量均为最低。可为健康、低脂油炸淀粉类食品加工提供参考。

CO2萃取作用对最小混相压力的影响实验研究

为了厘清CO2驱过程中萃取作用对最小混相压力的影响,明确气体前缘及气体波及后最小混相压力的变化情况,通过高温萃取实验、色谱分析手段,分别研究了不同萃取压力条件下CO2萃取率,以及萃取过程中萃取油与残余油组分分布特征,同时采用界面张力消失法定量分析萃取油、残余油最小混相压力的变化。实验结果表明:在实验温度95℃、实验压力10~45 MPa条件下,超临界CO2可以萃取原油各个碳数的组分,萃取油中C5-20摩尔质量达到80%以上;超临界CO2对原油的萃取率、萃取油最小混相压力及残余油最小混相压力,均与萃取压力正相关;受萃取作用及压力影响,在CO2驱替运移过程中最小混相压力是个动态变化值,最小混相压力满足关系:MMP残余油>MMP原油>MMP萃取油;萃取油、残余油最小混相压力与组分分布有关,地层油中影响混相的关键组分为C5-10组分和C26+组分。研究结果对进行CO2混相驱设计及混相带预测提供较好借鉴。

新型井下轴流式入口旋流器分析及优选

在国内陆地油田井下油水分离同井注采技术应用中,常规井下旋流器由于径向尺寸较大而经常受到限制,影响分离效率。为此,研发了2种新型井下轴流式入口旋流器,在降低旋流器径向尺寸的基础上,提高旋流器的分离性能。在明确新型轴流式旋流器结构特点、分离机理后,通过数值模拟分析,利用油相体积分布云图阐明不同结构旋流器内油相分布特点,指出循环流对旋流器分离性能的影响。研究速度矢量变化特点,掌握轴流式入口结构的作用及流体分布规律,利用压力降曲线,明确能耗、压力损失的关系。模拟分析结果表明,导流叶片轴流式旋流器切向速度差值为1.2 m/s、轴向速度差值1.5 m/s,溢流压力仅为0.02 MPa,分离效率高、能耗低,为特高含水区块的经济性开发提供技术支持。

Air flow patterns and noise analysis inside high speed angular contact ball bearings

The vortex formed around the rolling ball and the high pressure region formed around the ball-raceway contact zone are the principle factors that barricades the lubricant entering the bearing cavity, and further causes improper lubrication. The investigation of the air phase flow inside the bearing cavity is essential for the optimization of the oil-air two-phase lubrication method. With the revolutionary reference frame describing the bearing motion, a highly precise air phase flow model inside the angular contact ball bearing cavity was build up. Comprehensive factors such as bearing revolution, ball rotation, and cage structure were considered to investigate the influences on the air phase flow and heat transfer efficiency. The aerodynamic noise was also analyzed. The result shows that the ball spinning leads to the pressure rise and uneven pressure distribution. The air phase velocity, pressure and cage heat transfer efficiency increase as the revolving speed increases. The operating noise is largely due to the impact of the high speed external flow on the bearing. When the center of the oil-air outlet fixes near the inner ring, the aerodynamic noise is reduced. The position near the inner ring on the bigger axial side is the ideal position to fix the lubricating device for the angular contact ball bearing.

Synthesis of Polymethacrylates Used as Multifunctional Lubricating Oil Additives

In this paper, four kinds of polymethacrylates(PMAs) used as multifunctional additives were synthesized from quaternary C1—C14 methacrylate, among which sample 4 exhibited relatively better performance. According to the methacrylate ratio of sample 4, the optimized reaction conditions of PMA were explored by orthogonal experiments comprising 4 factors and 3 levels, and the optimized reaction conditions covered an initiator dosage of 0.8 %, a molecular weight regulator dosage of 0.4%, a reaction temperature of 95 ℃ and a reaction time of 8.5 h. When the optimized PMA samples were used to formulate the 75W/90 automotive gear base oil, they exhibited improved shear stability and good low temperature property. In comparison with foreign commercial polymethacrylate GP, the optimized PMA samples exhibited better thickening ability, similar shear stability and slightly weak low temperature property, with their performance being the same as GP's on the whole. The slight difference in the performance between the optimized PMA and GP was attributed to the difference of chain length of copolymers and the distribution of relative molecular mass between them.

Flame Spread over Aviation Kerosene with an Obstacle in Liquid Phase

The phenomena of flame spread over aviation kerosene with an obstacle in liquid phase are investigated experimentally through surface temperature measurement by using infrared camera,schlieren images of subsurface flow in front of and behind obstacle and residence time of flame obtained from video recording.Experimental results reveal that obstacle has no effect on gas phase controlled flame spread.But for liquid phase controlled flame spread,flame can be stopped by an obstacle with its top edge flush with oil surface,and the residence time decreases with the increase of initial temperature of fuel.That conduction and radiation only play a subsidiary role in flame spread over liquid fuel was proved by schlieren images and surface temperature profiles.