航空燃油柱塞泵滑靴静压润滑油膜计算分析

滑靴与斜盘是一对重要的摩擦副,滑靴与斜盘之间的油膜润滑性能对燃油柱塞泵的使用寿命有很大影响.通过数值计算,得到了排油区滑靴油膜厚度与转子转角、斜盘倾角、油池压力、柱塞压紧力之间的变化规律,建立油膜厚度变化的微分方程,给出在吸、排油一个周期内,滑靴油膜厚度的动态变化规律.利用油膜计算方法,可以分析滑靴运动一周,滑靴与斜盘间的油膜润滑状态,从而为合理设计航空燃油柱塞泵滑靴与斜盘摩擦副提供理论依据.      

基于CFD内流耦合仿真的燃油柱塞泵滑靴副动态润滑特性研究

针对航空燃油柱塞泵滑靴副自适应油膜的动态润滑问题,基于牛顿拉夫逊方法,建立了考虑滑靴副油膜支承作用与其动力学状态动态耦合关系的滑靴副润滑计算模型。在此基础上,计入前级部件内流作用对油膜特性的影响,通过CFD内流分析和Reynolds润滑模型相结合的仿真方法,对航空柱塞泵滑靴副及其前级部件进行了一体式联合仿真研究。研究结果表明:仿真与试验结果的误差保持在4.3%以内,CFD仿真方法可以实现对滑靴副前级部件内流场的准确模拟;转速从4kr/min增至5kr/min时,膜厚的最大倾覆值减小至原数值的27.15%,并且低压区滑靴厚度变化率的增大率最大可达62.02%;而出口压力增大率为66.7%时,引起全周期内膜厚变化率波动幅度不同程度的增大;在转动周期内,滑靴的自适应润滑效果通过油膜厚度场和压力场的耦合变化形成自适应动压支承效应来实现。     

轴向柱塞泵滑靴副的热结构耦合特性

为了改善轴向柱塞泵滑靴副的耐磨损性能,建立了滑靴与斜盘摩擦副的瞬态热结构耦合模型,分析压力冲击条件下滑靴的表面温度、应力以及变形的变化规律.研究结果表明:某型轴向柱塞泵中滑靴温度随柱塞腔压力呈周期性变化,滑靴温度范围为45.5~49.8℃,且滑靴的最高温度出现在泵的吸排油过渡区.当滑靴处于泵的排油区时,滑靴的最大轴向应力为250MPa,集中在滑靴油腔与密封带之间的边缘区域.滑靴的轴向应力分层显著,引起滑靴的变形分化,其变形量为12.5~15μm,出现在滑靴的边缘.由于滑靴的输入热流密度增强磨粒的剪切力,加剧滑靴表面的微切削和挤压变形,导致滑靴表面出现条状剥落和凹坑磨损,呈现出黏着和磨粒磨损特征.      

线接触零件部分热弹流润滑油膜厚度公式

采用弹性流体动力润滑理论和部分弹性流体动力润滑理论的分析方法,对弹流及部分弹流润滑线接触问题进行数值求解。通过联立求解结果,分析了接触表面间油膜厚度随载荷、滚动速度、滑滚比和进油温度等因素的变化规律,获得不同工况条件下的油膜厚度值,并依此提出一种新的油膜厚度公式。新公式考虑了热效应及表面粗糙效应影响,可用于高温、高速、重载工况。计算结果比Dowson-Higginson油膜厚度公式更符合于实验数据。     

基于DPM与VOF方法轴承腔内滑油瞬态特性对比

为了研究航空发动机轴承腔内油气两相流流动特性,分别采用DPM方法和VOF方法建立了完整的数学模型,并对轴承腔内的两相流动进行了非稳态的数值模拟,获得了不同转速情况下内壁面油膜厚度和滑油体积分数的动态变化过程。通过与实验数据的对比及两种方法计算结果的对比,验证了模型的合理性。进一步计算了增大滑油流量情况下腔内滑油分布。研究结果表明：油膜在轴承腔壁面经历从形成到基本稳定的过程,历时约0.8 s;油膜的生成位置及发展速度受转速影响较大,空气对油膜的剪切作用对油膜分布的均匀性有积极作用。     

液压泵摩擦副可靠性设计基本方法研究

阐述了液压泵摩擦副可靠性分析及设计的基本步骤和原则。作为实例,文中给出了滑靴耐磨可靠性设计所采用的（pv）应力模型新方法。     

轴承腔壁面液膜厚度数值模拟与实验测量

通过轴承腔壁面油膜厚度的实验测量以及数值模拟,对建立轴承腔壁换热模型、完善轴承腔热分析具有重要意义。通过轴承腔壁油膜流动进行量纲分析,提出了轴承腔表面的二维计算模型,并完成了对试验件的数值模拟。采用超声测量系统对轴承腔两个不同点处进行了油膜厚度测量,得到轴承腔油膜厚度随转速以及滑油流量的变化关系。将数值模拟结果与实验值进行对比表明:在计算工况条件下,测量点处最大误差小于8%,满足工程实践要求。     

航空燃油柱塞泵滑靴油膜的多目标优化设计

以锥形转子球面斜盘轴向燃油柱塞泵为研究对象,在分析滑靴油膜设计中的摩擦功率损失、泄漏功率损失、容积效率随滑靴的机械结构参数变化的基础上,基于遗传算法对上述多变量、多目标优化问题进行计算.权重系数法优化结果表明:优化后燃油柱塞泵设计点的摩擦功率损失和泄漏功率损失减少了7%左右,容积效率略微提升,并且优化得到的机械结构参数在不同转子转角和柱塞倾角的情况下也显示出性能上的优势,从而证明了多目标遗传算法对设计航空燃油柱塞泵油膜静压润滑是一种有效的方法.     

织构化配流副摩擦磨损性能试验

为改善轴向柱塞泵配流副的摩擦磨损性能,采用光刻-电解工艺,对配流副进行织构化,在配流副摩擦磨损试验机上进行试验研究.结果表明:织构化配流副能够有效减小摩擦因数,平均磨损截面面积和表面粗糙度的变化值都小于无织构配流副,不同于无织构配流副形成了比较严重的黏着磨损,微凹坑直径为100~300μm时磨损相对更小,配流副只产生磨粒磨损,此时平均磨损截面面积为无织构配流副试件的4.54%~7.14%.摩擦因数和平均磨损截面面积间有着良好的相关性.     

考虑油气传热传质耦合的轴承腔内壁油膜运动研究

为研究航空发动机轴承腔油气两相流动及内壁面油膜运动特性,建立了腔内油滴-空气双向耦合数学模型和内壁面油膜传热传质运动模型,并对油气流场及不同供油流量下油膜的流动进行计算,获得腔内两相流场特性及内壁面油膜厚度、周向速度分布。结果表明:在所计算工况中,双向耦合计算流场与单向计算结果至少相差10%,因而不可忽略油滴对空气流动的影响;腔内滑油蒸汽质量分数低于0.05%,则空气-油滴之间粘性力产生的拖曳作用是影响流场的主要因素;随着供油流量的增加,油膜厚度及周向速度都呈增加趋势,但与滑油流量的增幅并不成正比。与国外试验数据的对比证明所建数学模型合理且有效。     

Impact of the thermal effect on the load-carrying capacity of a slipper pair for an aviation axial-piston pump

A thermal hydraulic model based on the lumped parameter method is presented to analyze the load-carrying capacity of a slipper pair in an aviation axial-piston pump under specified operating conditions. Both theoretical and experimental results are presented to demonstrate the validity of the thermal hydraulic model. The results illustrate that the squeezing force and thermal wedge bearing force are the main factors that affect the film thickness and load-carrying capacity. At high oil temperature and high load pressure, the film thickness decreases with increasing clamping force due to a combined action of the squeezing bearing force and the thermal wedge bearing force, but the load-carrying capacity will increase. An increase of the film thickness is proven to be beneficial under high shaft rotational speed but especially dangerous as it strongly increases the ripple amplitude of the film thickness, which leads to decreasing the load-carrying capacity. The structural parameters of the slipper can be optimized to achieve desired performance, such as the slipper radius ratio and orifice length diameter ratio. To satisfy the requirement of the load-carrying capacity, the slipper radius ratio should be selected from 1.4 to 1.8, and the orifice length diameter ratio should be selected from 4 to 5.     

Variable load failure mechanism for high-speed load sensing electro-hydrostatic actuator pump of aircraft

This paper presents a novel transient lubrication model for the analysis of the variable load failure mechanism of high-speed pump used in Load Sensing Electro-Hydrostatic Actuator (LS-EHA). Focusing on the slipper/swashplate pair partial abrasion, which is considered as the dominant failure mode in the high-speed condition, slipper dynamic models are established. A forth sliding motion of the slipper on the swashplate surface is presented under the fact that the slipper center of mass will rotate around the center of piston ball when the swashplate angle is dynamically adjusted. Besides, extra inertial tilting moments will be produced for the slipper based on the theorem on translation of force, which will increase rapidly when LS-EHA pump operates under high-speed condition. Then, a dynamic lubricating model coupling with fluid film thickness field, temperature field and pressure field is proposed. The deformation effects caused by thermal deflection and hydrostatic pressure are considered. A numerical simulation model is established to validate the effectiveness and accuracy of the proposed model. Finally, based on the load spectrum of aircraft flight profile, the variable load conditions and the oil film characteristics are analyzed, and series of variable load rules of oil film thickness with variable speed/variable pressure/variable displacement are concluded.     

基于二维厚板模型的波箔片轴承静特性

建立平箔片的二维厚板有限元模型,运用有限单元法和有限差分法耦合求解Reynolds方程和气膜厚度方程,研究了在两个工作转速下气体波箔片轴承在中截面和边缘处最小气膜厚度随轴承承载力变化规律.通过数值仿真对该模型、一维梁模型、二维薄壳模型和文献实验数据进行对比分析,结果表明:在轴承中截面处,3个模型的最小气膜厚度仿真结果都与实验结果符合得很好,但在轴承边缘处,由于二维厚板模型考虑了平箔片的剪切效应,因此其最小气膜厚度比二维薄壳模型的结果更接近实验值,而一维梁模型只考虑轴承圆周方向,因此不能体现气膜厚度沿轴承长度方向的变化规律.通过研究,为分析箔片轴承动力学特性奠定了理论基础.      

Analysis of the cylinder block tilting inertia moment and its effect on the performance of high-speed electro-hydrostatic actuator pumps of aircraft

Electro-hydrostatic actuator (EHA) pumps are usually characterized as high speed and small displacement. The tilting inertia moment on the cylinder block produced by the inertia forces of piston/slipper assemblies cannot be ignored when analyzing the cylinder block balance. A large tilting inertia moment will make the cylinder block tilt away from the valve plate, resulting in severe wear and significantly increased leakage. This paper presents an analytical expression for the tilting inertia moment on the cylinder block by means of vector analysis. In addition, a high-speed test rig was built up, and experiments on an EHA pump prototype were carried out at high speeds of up to 10,000 r/min. The predicted nature of the cylinder block tilt at high speeds corresponds closely to the witness marks on the dismantled EHA pump prototype. It is suggested that more attention should be given to the tilting inertia moment acting on the cylinder block of an EHA pump since both wear and leakage flow between the cylinder block and the valve plate are very much dependent on this tilting moment.     

渐开线直齿轮的动力学与弹流润滑耦合

综合考虑时变啮合刚度和油膜刚度、表面粗糙度以及摩擦转矩等对动力学行为的影响,基于载荷分担理论和动力学理论建立了六自由度渐开线直齿轮摩擦动力学模型.采用解耦方法求解该摩擦动力学模型,即将摩擦动力学模型求解获得的动态轮齿作用力和表面速度用于润滑分析中,反过来润滑分析获得的摩擦因数和油膜刚度将用于动力学分析计算中.通过实例研究了摩擦学特性和动力学行为以及两者之间的耦合关系.研究表明:考虑耦合效应后齿轮综合刚度略有下降.滑动摩擦力对垂直于啮合线方向的动态响应的影响比较显著,摩擦力会加剧该方向的振动.动态载荷对油膜厚度、油膜承载比例、油膜温升和摩擦因数影响均较大,且动力学行为对油膜温升分布的影响取决于相对滑动速度的大小.      

高温高压下平板预膜喷嘴初次雾化试验

为了深入探究预膜喷嘴燃油初次雾化机理,试验研究了高温高压条件下不同工况参数对平板预膜喷嘴初次雾化特性的影响规律.采用高速摄影可视化技术和马尔文粒度仪获取了预膜平板液膜厚度、液膜波动形态以及索泰尔平均直径(SMD)等雾化特性.利用图像后处理技术提取液膜厚度,试验结果表明:液膜厚度随进气压力、进气温度和进口韦伯数的增加而减...