柱塞倾角对航空柱塞泵性能的影响分析

通过对柱塞泵中柱塞的运动方程和柱塞泵的瞬时供油量方程进行分析,利用AMEsim工程仿真软件,建立了某型航空发动机柱塞泵的仿真模型,通过仿真分析了柱塞倾角对柱塞行程、柱塞泵的流量脉动和压力脉动的影响,仿真结果表明柱塞倾角是影响泵流量脉动的重要因素,适当增大柱塞倾角,可以增大柱塞的行程,增加泵的供油量,还能够改善柱塞泵流量的脉动。     

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.     

轴向柱塞泵多学科融合建模与集成优化

为了实现机液耦合条件下轴向柱塞泵的精确建模和优化设计,提出了轴向柱塞泵多学科融合建模与集成优化方法。以国产I3V2-10S型轴向柱塞泵为对象,分别建立了ADAMS机械系统模型和AMESIM液压系统模型,通过ADAMS和AMESIM之间的接口模块设计实现了柱塞泵机液耦合建模和联合仿真,并利用iSIGHT软件集成了该机液耦合模型,以该柱塞泵出口体积流量脉动率最小为目标,对配流副中吸排油节流口最大开口等效直径、吸排油闭死角、柱塞包角、吸排油预开口量等参数进行了优化设计。结果表明:在负载工况分别为10、14、18、22、26、30MPa时,优化后的泵出口流量脉动率比优化前分别降低了14.59%、18.57%、21.50%、23.44%、24.03%、25.49%,最后通过实验验证了仿真和集成优化数据的正确性。      

二维燃油泵的设计与研究

提出一种新型的二维燃油泵，说明了其诸多优点。为研究其结构性流量脉动，利用仿真软件AMESIM建立了二维燃油泵的仿真模型进行理论研究，并进行了实验验证。通过齿轮泵与轴向柱塞泵的对比，说明了轴向柱塞泵在燃油系统应用中的优势。针对轴向柱塞泵中存在的一些不可避免的缺陷，提出了能避免这些缺陷的二维燃油泵。通过解释二维燃油泵的结构组成与工作原理，说明了二维燃油泵的优势，包括结构力平衡、工作效率高、无直接的滑动摩擦副和无结构性流量脉动等。为了解释无结构性流量脉动这一优点，进行了仿真分析与实验验证，验证了二维燃油泵具有无结构性流量脉动这一潜力。     

Numerical investigation of effect of a centrifugal boost impeller on suction performance of an aircraft hydraulic pump

An integrated boost impeller can effectively improve the suction performance of an aircraft hydraulic pump (AHP). It must be designed very carefully; however, few studies thus far have investigated boost impellers. To explore the effect of the boost impeller, this study developed a three-dimensional computational fluid dynamics (CFD) model for an AHP based on the k-ε turbulence model and full cavitation model. The results of verification tests demonstrated that the model is reliable for simulating the delivery characteristics of piston pumps and the boost capacity of the inlet impeller. Steady-state simulations reveal that the boost impeller can remarkably improve the suction performance and mitigate the cavitation damage due to insufficient fluid filling while only consuming a small proportion of the total input power. Transient-state simulations show that the pump with an impeller is more capable of catching up with a sudden increase in flow demand, and it has a lower suction flow ripple and impact. However, such a boost impeller also has some limitations such as magnifying the suction pressure fluctuation and having little effect on mitigating the cavitation caused by the back-flow jet.     

An adaptive-order particle filter for remaining useful life prediction of aviation piston pumps

An accurate estimation of the remaining useful life (RUL) not only contributes to an effective application of an aviation piston pump, but also meets the necessity of condition based maintenance (CBM). For the current RUL evaluation methods, a model-based method is inappropriate for the degradation process of an aviation piston pump due to difficulties of modeling, while a data-based method rarely presents high-accuracy prediction in a long period of time. In this work, an adaptive-order particle filter (AOPF) prognostic process is proposed aiming at improving long-term prediction accuracy of RUL by combining both kinds of methods. A dynamic model is initialized by a data-driven or empirical method. When a new observation comes, the prior state distribution is approximated by a current model. The order of the current model is updated adaptively by fusing the information of the observation. Monte Carlo simulation is employed for estimating the posterior probability density function of future states of the pump’s degradation. With updating the order number adaptively, the method presents a higher precision in contrast with those of traditional methods. In a case study, the proposed AOPF method is adopted to forecast the degradation status of an aviation piston pump with experimental return oil flow data, and the analytical results show the effectiveness of the proposed AOPF method.     

Remaining useful life prediction based on the Wiener process for an aviation axial piston pump

An aviation hydraulic axial piston pump’s degradation from comprehensive wear is a typical gradual failure model. Accurate wear prediction is difficult as random and uncertain char-acteristics must be factored into the estimation. The internal wear status of the axial piston pump is characterized by the return oil flow based on fault mechanism analysis of the main frictional pairs in the pump. The performance degradation model is described by the Wiener process to predict the remaining useful life (RUL) of the pump. Maximum likelihood estimation (MLE) is performed by utilizing the expectation maximization (EM) algorithm to estimate the initial parameters of the Wiener process while recursive estimation is conducted utilizing the Kalman filter method to estimate the drift coefficient of the Wiener process. The RUL of the pump is then calculated accord-ing to the performance degradation model based on the Wiener process. Experimental results indi-cate that the return oil flow is a suitable characteristic for reflecting the internal wear status of the axial piston pump, and thus the Wiener process-based method may effectively predicate the RUL of the pump.     

Performance optimization of grooved slippers for aero hydraulic pumps

A computational fluid dynamics(CFD) simulation method based on 3-D Navier–Stokes equation and Arbitrary Lagrangian–Eulerian(ALE) method is presented to analyze the grooved slipper performance of piston pump.The moving domain of grooved slipper is transformed into a fixed reference domain by the ALE method,which makes it convenient to take the effects of rotate speed,body force,temperature,and oil viscosity into account.A geometric model to express the complex structure,which covers the orifice of piston and slipper,vented groove and the oil film,is constructed.Corresponding to different oil film thicknesses calculated in light of hydrostatic equilibrium theory and boundary conditions,a set of simulations is conducted in COMSOL to analyze the pump characteristics and effects of geometry(groove width and radius,orifice size) on these characteristics.Furthermore,the mechanics and hydraulics analyses are employed to validate the CFD model,and there is an excellent agreement between simulation and analytical results.The simulation results show that the sealing land radius,orifice size and groove width all dramatically affect the slipper behavior,and an optimum tradeoff among these factors is conducive to optimizing the pump design.     

Modeling and Optimal Design of 3 Degrees of Freedom Helmholtz Resonator in Hydraulic System

Three degrees of freedom (3-DOF) Helmholtz resonator which consists of three cylindrical necks and cavities connected in series (neck-cavity-neck-cavity-neck-cavity) is suitable to reduce flow pulsation in hydraulic system. A novel lumped parameter model (LPM) of 3-DOF Helmholtz resonator in hydraulic system is developed which considers the viscous friction loss of hydraulic fluid in the necks. Applying the Newton’s second law of motion to the equivalent mechanical model of the resonator, closed-form expression of transmission loss and resonance frequency is presented. Based on the LPM, an optimal design method which employs rotate vector optimization method (RVOM) is proposed. The purpose of the optimal design is to search the resonator’s unknown parameters so that its resonance frequencies can coincide with the pump-induced flow pulsation harmonics respectively. The optimal design method is realized to design 3-DOF Helmholtz resonator for a certain type of aviation piston pump hydraulic system. The optimization result shows the feasibility of this method, and the simulation under optimum parameters reveals that the LPM can get the same precision as transfer matrix method (TMM).     

液压泵脉动模型的故障诊断方法研究

采用液压泵的脉动参数方法进行故障诊断试验研究,在介绍了必要的数学模型和参数测量原理后,着重定性分析了液压泵游隙故障下泵源脉动参数Ｑｓ,Ｚｓ的变化,并给出了判断此种故障的参考阈值方法,试验表明本方法在液压故障诊断方面具有的应用前景。     

Multi-parameter load sensing pump model simulation and flow rate characteristics research

Load sensing pumps have been widely used in diverse hydraulic systems. Studies show that structural parameters have undeniable impacts on the characteristics and efficiency of the load sensing pump. The main purpose of this article is to study the influence of load sensing pump structure parameters on flow characteristics. In the present study, a nonlinear multi-parameter model is proposed for this type of pump. In this model, different parameters, including spool clearance, spool covering amount, internal leakage are considered to reflect the displacement adjustment process of the load sensing pump. Moreover, a frequency sweep method is proposed to analyze the frequency domain of the nonlinear mathematical model. An experiment rig was built to study the influence of key structural parameters on the dynamic follow-up characteristics of the pump flow. The obtained results show that the diameter of the orifice d can significantly affect the working characteristics of the pump. It is found that a large diameter of the orifice d can improve the phase following ability of the system, while a small diameter of the orifice d can reduce the bypass flow rate and increase the amplitude following ability. This paper provides a new consideration to study the dynamic follow-up characteristics of the load sensing pump.     

二维合成射流组合效应的数值研究

采用数值模拟的方法,研究了一列合成射流对二维平板流动壁面的影响,对合成射流组合效应进行了分析。结果表明:在不同的开孔角度和振动相位下,合成射流组合效应明显,对壁面平均剪切应力改变显著,最大变化约15%,对壁面压力改变较小,最大变化约0.5%,;对于流场壁面压力和剪切应力分布,斜开孔比直开孔改变要大,异相位射流比同相位射流改变要大;异相位振动模式下,壁面平均压力和剪切应力值波动较小,变化比较平稳。     

柱塞泵热力学建模与仿真

针对航空行业广泛应用的柱塞泵的热力学特性,提出了一种分析和建模的方法.应用能量守恒定律推导并建立了集中参数的航空柱塞泵的热力学模型,并针对柱塞泵的内部结构进行了较详细的传热分析.将此建模和分析的方法应用于包含航空柱塞泵的一个典型液压回路.通过对航空柱塞泵的热力学实验与仿真结果的比较证明了建模方法的有效性.     

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。     

全流量补燃循环发动机系统参数模型与设计(Ⅱ)参数设计

在全流量补燃循环发动机系统动力平衡模型的基础上,研究了氢发汗冷却流量、燃烧室压力和燃烧室混合比对发动机系统参数的影响规律.研究结果表明:在发动机推力和喷管扩张比保持恒定时,①随着氢发汗冷却流量的增加,燃料泵扬程大幅度增大,氧化剂泵扬程小幅度减小;②当燃烧室压力在20MPa之前,泵的扬程增加与燃烧室压力的增加近似成线性;...     

Review of cylinder block/valve plate interface in axial piston pumps: Theoretical models,experimental investigations,and optimal design

Axial piston pumps have been widely used in aircraft hydraulic systems to supply the system with pressurized fluid. The continuous improvement of the aircraft performance has put forward the demand on aviation piston pumps for high power density, safety, and reliability. The lubricating interfaces in axial piston machines are the key design issue that greatly determines the pump performance and service life. The cylinder block/valve plate interface is one of these critical lubricating interfaces and has received considerable attention from many researchers in the last half century. This study aims to review the state‐of‐the‐art literature on the cylinder block/valve plate interface comprehensively and systematically. First, we introduce various theoretical models developed to investigate the lubrication behaviors of the interface and compare them in terms of their assumptions and limitations. Second, the experimental studies on the cylinder block/valve plate interface are presented comprehensively, where the involved test rigs are divided into three types according to their fidelity levels and measurement functionality. Third, we summarize some typical approaches of structure optimization, surface shaping, and surface strengthening, which help improve the load-carrying and anti-wear capacities of the interface under severe operating conditions. Finally, the challenges and future trends of the cylinder block/valve plate interface research are discussed briefly.     

二维活塞航空燃油泵容积效率分析

提出了一种二维活塞燃油泵，该泵利用二维活塞的旋转运动将配流机构集成到活塞上，去除了传统柱塞泵独立的配流机构，简化了泵的结构、提升了泵的功率密度，而且由于主要运动机构采用了滚动轴承支撑，免除了滑动摩擦副及其产生的泄漏，提高了效率。对泵的容积效率进行理论分析和实验研究。结合泵的结构原理分析了造成容积损失的内泄、外泄及油液压缩性等3种主要原因；应用层流和紊流的缝隙流动基本理论推导出泄漏解析表达式，着重分析了不同配流开口形式产生的内泄漏；综合考虑油液压缩性和泄漏获得了容积效率数学模型。理论研究表明采用负开口配流形式可以有效减小内泄漏，定量分析了泄漏流量与负开口量的关系，同时利用Fluent进行配流过程中泵腔内的流场数值模拟，结果表明可以有效减小油液倒灌。为了验证理论分析的有效性，制作二维活塞燃油泵样机，以航空煤油为介质进行台架实验。样机实验结果表明在负载压力2 MPa，转速从1 000 r/min到5 000 r/min，容积效率从93.6%提升到98.1%；当转速为2 000 r/min，负载压力从1 MPa增大到5 MPa，容积效率从97.5%降低到92.3%。以现有的齿轮泵和柱塞泵相比容积效率显著提高，理论与实验的结果偏差在4%以内，表明理论分析的有效性和正确性。     

高速角接触球轴承腔内气液两相流模拟分析

基于轴承腔内气液两相流流动模型,采用VOF方法和MRF模型对高速角接触球轴承简化模型内润滑油的流动特性进行数值计算,获得腔内速度、压力以及润滑油分布情况。分析轴承转速和润滑油进口流量等参数对油液体积分数的影响,以及轴承腔内润滑油的流动轨迹和润滑油进入腔内的影响机理。结果表明:轴承高速转动阶段,润滑油在滚动体和保持架的搅动作用,在腔内局部形成漩涡不利于润滑油的流动;轴承腔内两相流场的环间压力具有周期性特点,喷射润滑油很难穿过环间压力进入腔内;腔内油液体积分数随轴承转速的升高而降低,随供油量的增加而增加,呈非线性关系;喷射角度对环间油液体积分数和滚道油液体积数的影响很大,选择合适的喷射角度能够得到更好的润滑效果。该研究结果对高速轴承润滑设计提供了一定的参考依据。      

Hydraulic piston pump in civil aircraft: Current status,future directions and critical technologies

The piston pump is the key power component in the civil aircraft hydraulic system, and the most common pump used in the aviation field is the pressure compensated variable displacement type. In this review paper, a basic introduction to the civil aircraft piston pump is presented, including the classification, structure, working principle, design features, and achievements by some research groups. Then, the future directions of the aircraft pump are reported from various perspectives. Further, the critical technologies are analyzed and summarized in detail from six thrust areas: friction couples, noise reduction, inlet boost, thermal management, fault diagnosis and health management, and mechanical seal. Finally, the challenges and limitations of the research on the aircraft pump are discussed to provide valuable insight for future scholars.     

某型航空螺旋离心泵的性能分析与计算

在分析国外某型航空发动机用螺旋离心泵流体运动规律的基础上,建立了叶轮中液体的简化流动模型,研究了泵的扬程、功率和效率的计算方法。结果表明,该计算方法对于该泵的改进改型设计有指导作用。