螺杆泵抽油杆有限元分析

如何降低螺杆泵抽油杆的应力水平,提高工作寿命是石油开采设备研究中一个急需解决的力学问题。分析了螺杆泵抽油杆的工作状态,建立了该杆三种可能的力学模型,以实际断裂的典型的抽油杆为例,进行了有限元分析。抽油杆的内力和应力水平与杆的"麻花"程度密切相关,模型3的模拟结果与抽油杆的实际断裂情况相吻合。模型3较真实地反映了抽油杆工作状况,为降低抽油杆的应力水平,提高工作寿命提供了理论根据。     

航空泵试验台驱动变结构控制

飞机液压系统泵源需进行地面试验,采用变频调速器＋异步电机＋增速箱的驱动形式是航空泵进行地面试验最先进有效的方法之一.建立了矢量控制变频调速驱动下航空泵试验台驱动系统的数学模型,针对航空泵试验时由于负载变化泵转速不能保持恒定的问题,采用积分滑模面的滑模变结构控制策略,并构造Lyapunov函数证明其稳定性.为降低输出抖振现象,提出采用模糊控制监督下的滑模变结构控制和伪微分反馈(PDF, Pseudo Derivative Feedback)控制相结合的控制策略,仿真及实验结果表明,该控制方法有很高的控制精度,在保持滑模变结构控制鲁棒性强的前提下降低了输出抖振现象.      

液体火箭上面级发动机用超低比转数泵研究

为了研制出液体火箭上面级发动机用高性能超低比转数离心泵,采用变曲率复合离心轮、加大流量法等设计措施,设计了比转数分别为24和33的两种高速小流量高扬程离心泵,并应用Fluent流体计算软件对其内流场进行了分析计算。所设计的泵已参加了相关试验,试验结果表明泵性能稳定,扬程曲线无“驼峰”,功率无过载,达到了设计目的。     

Experimental study of an insert and its influence on churning losses in a high-speed electro-hydrostatic actuator pump of an aircraft

The speed of an Electro-Hydrostatic Actuator (EHA) pump can recently reach 20000 r/min, and its churning losses increase obviously with an increasing speed, which results in low efficiency and thus increasing heat in aircraft EHA systems. In order to reduce churning losses at high speeds, more attention should be given to the design of an insert. In this paper, the effect of an insert with different design parameters on churning losses is investigated through Computational Fluid Dynamics (CFD) simulation and experiments by calculating the difference between churning losses torques of the test pump with and without the insert based on a high-speed churning losses test rig. Analytical results show that the gap between the insert and the cylinder is critical for churning losses reduction. It is found that the churning losses of the test pump can be reduced with a decreasing gap between the cylinder block and the insert at high speeds. This is because the insert can decrease the turbulence occurrence at high speeds. The results can be used for flow field analysis and optimization of the high-speed EHA pump and provide a new method for improving efficiency of high-speed EHA pumps.     

航天器热控系统中的热泵-蓄冷组合方案

提出了旨在降低热控系统质量的热泵-蓄冷组合热控方案。通过对负荷进行预测，对热泵蓄冷系统的集成模式，系统的运行策略，以及蓄冷设备的容量等问题进行了分析。结果表明：通过合理优化系统的运行参数，热泵蓄冷组合方案能实现热控系统的轻量化设计要求，在未来航天热管理系统中具有相当的应用潜力。     

双端供油泵诱导轮与上端泵口卡滞故障分析与预防

通过对调试现场发生的故障现象进行分析和判断，找出整机调试中客观存在的问题，通过采取科学有效的方法与措施，杜绝后续同类故障的持续发生。     

Constant power H∞ stabilization control strategy on airborne pump supplying system

以机载泵源系统的恒功率控制为目标，针对作业任务中系统负载随时间变化的情况，采用使液压系统输出功率保持恒定的控制方式来达到充分利用发动机功率的目的，对于机载泵源控制系统的主要被控对象——轴向柱塞式变量泵，建立了其状态方程和流量输出方程，采用H。鲁棒镇定控制策略实时调节泵的排量，仿真结果表明：当负载变化时，系统能根据压力的变化快速转换到恒功率工作曲线下对应的流量状态，所设计的H。控制器能够减小干扰和模型参数不确定对系统稳定性的影响，具有良好的鲁棒性，表明该方法用于机载液压系统可以改善系统工作性能，提高系统功率的利用率。     

Modeling and control of a novel electro-hydrostatic actuator with adaptive pump displacement

The variable pump displacement and variable motor speed electro-hydrostatic actuator (EHA), one of the three types of EHAs, has advantages such as short response time, flexible speed regulation, and high efficiency. However, the nonlinearity of its double-input single-output system poses a great challenge for system control. This study proposes a novel EHA with adaptive pump displacement and variable motor speed (EHA-APVM). A closed-loop position is realized using a servomotor. Moreover, the displacement varies with the system pressure; thus, the EHA-APVM is a single-input and single-output system. Firstly, the working principles of the EHA-APVM and the pump used in the system are introduced. Secondly, a nonlinear mathematical model of the proposed EHA-APVM control system is established, and a feedback back-stepping (FBBS) control algorithm is introduced to transform the complex nonlinear system into a linear system on the basis of the back-stepping control theory. Finally, simulation results prove that the EHA-APVM has a quick response and high robustness to variations of the load and the pump displacement. In this work, the size and weight of the motor are significantly reduced because the maximum power requirement is reduced, which is very beneficial for using the actuator in airborne equipment.     

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.     

二次启动前火箭发动机泵构件温度特性数值计算

用数值计算的方法研究了液体火箭发动机在二次启动前，发动机泵系统各构件的温度特性和泵腔含汽率。建立了基于集总参数法的发动机启动前排放过程中涡轮、泵及进口管的温度变化计算模型。排放冷却过程中冷却剂N2O4的单相强制对流换热系数用Dittus-Boelter公式计算，流动沸腾换热系数采用Shan M M强化模型。并对某液体火箭发动机二次启动前排放过程涡轮泵系统各构件温度变化和泵腔含汽率进行了计算，模型计算结果与试车数据吻合良好，研究结果表明，二次启动前的主动排放过程对泵壳体及进口管的冷却效果很好。