几种低粘度润滑介质下动静压轴承的性能分析

以火箭发动机涡轮泵为典型应用背景 ,研究空间工程低粘度非油润滑滑动轴承 ,运用数值方法计算、分析了多种润滑介质下动压、纯静压、动静压润滑性能 ,结果表明 :就承载能力而言 ,粘度相对较大时动压轴承较佳 ,粘度相对较小时动静压轴承较佳 ,但轴承的选型需综合考虑多项轴承性能及应用的特定要求。文中提供了轴承承载能力、流量、功耗等关键性能参数的计算结果和详细的对比分析 ,为深入研究火箭发动机涡轮泵滑动轴承的可行性提供了基础 ,对其他应用亦有参考意义     

涡轮泵流体静压轴承设计及性能特性分析

针对流体静压轴承在液体火箭发动机涡轮泵中的设计和应用,以现有的滚动轴承支承的涡轮泵转子为应用对象,提出流体静压轴承的参数设计思路,采用粒子群优化算法设计得到支承刚度最大化的轴承结构参数组合,并计算分析所设计轴承的性能以及轴承-转子系统的动力学特性。分析表明：优化设计得到流体静压轴承的承载力和支承刚度可以满足要求,但轴承总流量达泵流量的21%,这会显著降低涡轮泵的总体效率;仅将滚动轴承改为流体静压轴承,而不改变其他结构或布局,转子的稳定性不能满足要求;涡轮泵流体静压轴承转子系统设计时应尽量将轴承布置在转子位移较大的位置,以充分发挥其阻尼作用。     

无泄漏磁传动涡轮泵的研究

针对于液体火箭发动机，研究一种新型磁传动密封涡轮泵的原理，利用磁超距特性，化动密封为静密封，可以实现零泄漏，有望解决涡轮泵最常见和极其危险的泄漏故障，从而提高火箭发射的可靠性。     

涡轮泵实时故障检测的多特征参量自适应阈值综合决策算法

为了实时监控液体火箭发动机涡轮泵的状态,提高安全性,降低故障带来的破坏程度,提出了一种多特征参量自适应阈值综合决策算法(MATA)。研究了该算法的特征参量选取、阈值区间的确定、阈值的自适应计算(包括特征参量均值与标准方差的自适应计算)、故障综合决策逻辑、故障数据对阈值贡献的剔除等方法,利用某型火箭发动机地面试车涡轮泵振动测量数据和某型转子试验平台实时测量数据对该算法进行离线和实时在线故障检测试验验证,结果表明MATA没有发生误检测情况,具有实时故障检测的能力。因此,MATA适合于液体火箭发动机涡轮泵的实时故障检测。     

动密封环研磨中材料去除率建模及仿真研究

液体火箭的寿命主要受发动机影响,涡轮泵又是发动机的心脏,所以涡轮泵性能至关重要,其平稳运行对火箭发动机的安全运行意义重大。影响涡轮泵稳定运行的核心问题包括轴承和密封的磨损、变形及失效等。文中围绕涡轮泵密封性中的重要组成部件——动密封环的研磨工艺进行研究。对动密封环研磨中材料去除率进行模型构建,研究其去除机理。对材料去除模型工艺参数进行仿真计算,对照研磨试验结果,把研磨加工压力、研磨转速、研磨时间工艺参数作为要素核心。所得的仿真结果可对研磨试验起到预测作用,以提高动密封环加工研磨效率。     

液体火箭发动机氢、氧涡轮泵支撑结构分析

利用有限元法对某火箭发动机氢、氧涡轮泵的支撑结构进行了分析，获得了外载荷在氢、氧涡轮泵上、下支撑中力的分配比例关系；得到了推力室和氢、氧涡轮泵及其支撑结构的应力、变形分布；并通过调整推力室材料常数的方法，模拟了推力室的温度变化对氢、氧涡轮泵支撑结构的影响。     

多重结构神经网络在液体火箭发动机故障诊断中的应用研究

根据液体火箭发动机的结构特点和故障诊断过程的特性 ,分析了复杂设备诊断过程的层次性 ,建立了复杂设备故障诊断的多重神经网络模型结构 ,并将其应用于液体火箭发动机涡轮泵的故障诊断 ,结果表明 ,该方法可有效地降解复杂系统故障诊断问题的复杂性、具有快速诊断能力     

液氢中球轴承和环形密封的超高速性能

未来空间传输系统需要以轻质量、高性能为特点的先进液氢／液氧火箭发动机以减少发射成本和提高效率。为了实现这种发动机，需要使用高压高速涡轮泵，这种涡轮泵可以给燃烧室提供低温液影液氢燃料。涡轮泵的转子转速受到轴承如值的限制（如值等于轴承内径（mm）与旋转速度（r／min）的乘积）。     

诱导轮旋转空化-诱发不稳定现象的研究与进展

在大型先进火箭发动机的研制过程中都遇见了推进剂供应泵诱导轮中发生旋转空化。其诱发的流场脉动和转子振动会严重影响液体火箭发动机的性能、稳定性和寿命。引起世界航天大国的高度重视。本文综述国外通过理论分析、数值模拟和实验研究的方法针对各种模式旋转空化的特征开展的研究工作现状，并简要介绍成功用于抑制火箭发动机诱导轮中这种现象的技术。     

两种滑动轴承的应用和比较

通过对液体静压和液体动静压两种轴承的理论分析和实际应用比较，说明了液体动静压滑动轴承的优点。     

密封和内阻尼对火箭发动机液氢涡轮泵转子系统动力稳定性的影响

考虑内阻尼的Timoshenko梁一轴有限元离散化转轴,用Muszynska密封力模型描述非线性密封流体激振力,建立实际火箭发动机液氢涡轮泵转子系统的非线性有限元模型。结合已有试验数据,结合打靶法和Floquet 理论研究该系统在刚性支承和柔性支承两种工况下密封和内阻尼对系统稳定性的影响。分析轴承阻尼、轴向雷诺数以及密封各参数在两种支承下对系统临界失稳角速度的影响。     

The tribological behavior of Ni–Cu–Ag-based PVD coatings for hybrid bearings under different lubrication conditions

In a cryogenic environment, components like bearings with interacting surfaces in relative motion (tribosystems) often generate undesired heat and experience high wear. Because the properties of conventional bearing materials like stainless steel cannot be applied to this temperature range, the PVD coating based on metal–metal pairs with better frictional properties must be employed. To test the suitability of the Ni–Cu–Ag-based PVD coatings of hybrid bearings for liquid rocket engine turbopumps and to obtain reliable coating material data in the extreme environment, the tribological behaviors of coatings under the cryogenic fluid (liquid oxygen and liquid nitrogen) and water lubricated conditions are studied, respectively. In the paper, the specimens are in a vibrocryotribometer with the ball-on-plane contact type, and various running conditions in terms of lubricants, contacting loading, and contacting velocity are examined. The simulated experiment for testing the actual tribological performance of Ni–Cu–Ag-based PVD coatings for hybrid bearings is tested. The results of the tests indicate that the coatings can be suitable for cryogenic tribosystems of turbopumps. In the cryogenic environment, the volume wear rate of coatings increases rapidly with the contacting loading, but 15 min later, the volume wear volume of coatings turns into 2.5–15×10⁻⁴ mm³. Besides, under the liquid oxygen condition in simulating the liquid rocket engine turbopumps environment, the friction coefficients are 0.03–0.1.     

Experiments on cavitation instability of a two-bladed turbopump inducer

The turbopump is a pressurizing system that supplies liquid propellants to the combustion chamber of a rocket engine at high pressure. As an integral component of a high-speed pumping system, the inducer used in a turbopump is forward-attached to an impeller to improve suction performance. This paper describes an experimental investigation on the flow instabilities of a two-bladed axial inducer due to cavitation. Cavitation development and its instabilities were analyzed. Asymmetric cavitation and cavitation surge were observed, and characterized by measuring the inlet pressure fluctuation for various cavitation numbers and flow coefficients. As flow coefficient decreases, the increased intensity of asymmetric cavitation was observed with an increased inception number of asymmetric cavitation. The frequency of the detected cavitation surge in the 4–10Hz range varied depending on the cavitation number. The instantaneous transition to cavitation surge appeared at the end of asymmetric cavitation as the cavitation number decreased. However, a further decrease in cavitation number resulted in the stable operation of the inducer with low values of pressure fluctuation. Finally, an intensive cavitation surge appeared after a significant amount of head loss.     

涡轮泵实时故障检测的快速支持向量机算法

提出了一种基于边界样本的快速支持向量机(support vector machine,SVM)算法用于液体火箭发动机涡轮泵实时故障检测。算法按一定步长将涡轮泵振动信号分段,再将每个步长信号平分为多段且计算每段信号的均方根、裕度因子和峭度,并将之组合为3维向量作为故障特征,以每个步长信号中的故障样本点数目作为判断故障的依据;算法采用条件正定核函数计算原始样本集中正常样本与故障样本之间的距离,选择边界样本作为新的训练样本集,并以此计算支持向量并构造决策函数。用某型号涡轮泵振动加速度信号对算法进行验证,结果表明对包含5 600个故障样本和5 600个正常样本的原始训练样本集,算法的训练时间为0.68 s。对时长20.80 s的待检信号,算法检出故障时刻为20.43 s,比故障真实出现时刻晚0.42 s(在0.5 s之内)。该算法大幅度提高了训练速度与分类速度,具备良好的精确性与实时性。     

发动机试验用液氮（液氧）贮箱的研制

论文介绍了一种粉末真空液氮／液氧贮箱,用于承担某液体火箭发动机试验。该低温储存容器采用立式夹套结构。使用珠光砂真空绝热,几何容积6．2m3综合考虑该压力容器工作环境、制造工艺性、安装条件及空间的限制以及维护成本等诸多因素,详细介绍了研制中材质的选择、结构特点以及漏热计算、相关试验等关键技术。     

Current Status of Hybrid Bearing Damage Detection

Advances in material development and processing have led to the introduction of ceramic hybrid bearings for many applications. The introduction of silicon nitride hybrid bearings into the high-pressure oxidizer turbopump on the space shuttle main engine led NASA to solve a highly persistent and troublesome bearing problem. Hybrid bearings consist of ceramic balls and steel races. The majority of hybrid bearings utilize Si₃N₄ balls. The aerospace industry is currently studying the use of hybrid bearings and, naturally, the failure modes of these bearings become an issue in light of the limited data available.

In today's turbine engines and helicopter transmissions, the health of the bearings is detected by the properties of the debris found in the lubrication line when damage begins to occur. Current oil debris sensor technology relies on the magnetic properties of the debris to detect damage. Because the ceramic rolling elements of hybrid bearings have no metallic properties, a new sensing system must be developed to indicate the system health if ceramic components are to be safely implemented in aerospace applications. The ceramic oil debris sensor must be capable of detecting ceramic and metallic component damage with sufficient reliability and forewarning to prevent a catastrophic failure.

The objective of this research is to provide a background summary on what is currently known about hybrid bearing failure modes and to report preliminary results on the detection of silicon nitride debris in oil using a commercial particle counter.     

Numerical calculation of thermal effect on cavitation in cryogenic fluids

A key design issue related to the turbopump of the rocket engine is that cavitation occurs in cryogenic fluids when the fluid pressure is lower than the vapor pressure at a local thermodynamic state. Cavitation in cryogenic fluids generates substantial thermal effects and strong variations in fluid properties, which in turn alter the cavity characteristics. To date, fewer investigate the thermal effect on cavitation in cryogenic fluids clearly by the numerical methods due to the difficulty of the heat transfer in the phase change process. In order to study the thermal effect on cavitation in cryogenic fluid, computations are conducted around a 2D quarter caliber hydrofoil in liquid nitrogen and hydrogen respectively by implementing modified Merkle cavitation model, which accounts for the energy balance and variable thermodynamic properties of the fluid. The numerical results show that with the thermal effect, the vapour content in constant location decreases, the cavity becomes more porous and the interface becomes less distinct which shows increased spreading while getting shorter in length. In the cavity region, the temperature around the cavity depresses due to absorb the evaporation latent heat and the saturation pressure drops. When the vapour volume fraction is higher, the temperature depression and pressure depression becomes larger. It is also observed that a slight temperature rise is found above the reference fluid temperature at the cavity rear end attributed to the release of latent heat during the condensation process. When the fluid is operating close to its critical temperature, thermal effects on cavitation are more obviously in both the liquid nitrogen and hydrogen. The thermal effect on cavitation in liquid hydrogen is more distinctly compared with that in liquid nitrogen due to the density ratio, vapour pressure and other variable properties of the fluid. The investigation provides aid for the design of the cryogenic pump of the liquid rocket.     

某卫星液体火箭发动机推力偏心测试技术研究

卫星火箭发动机推力矢量测试,是一项高新技术火箭测试技术.根据某卫星液体火箭发动机推力矢量的特点和测量要求,阐述了待测推力矢量参数的定义,然后对转台测试原理和计算方法进行了简单的介绍.     

气液两相流对发动机主轴承润滑性能影响的分析

润滑油中出现的气液两相流现象是发动机主轴承工作中较常出现的现象,对发动机工作性能有较大影响。本文基于主轴承中润滑油气液两相均匀流动模型,利用湍流理论和有限差分技术,通过求解Navier-Stokes方程,获得了润滑油含气率、转子转速以及润滑油入口速度和轴承腔润滑油出口压力和速度的关系。本文的工作对于发动机主轴承润滑设计具有一定的参考价值。