O形密封圈在锥面密封中的结构设计与计算

介绍在两个互相配合的锥面上使用0形密封圈的结构设计与计算。     

雷达吸波涂层胶粘剂的现状与发展

综述了雷达吸波涂层胶粘剂的发展概况，论述了三种综合性较好，工艺稳定的胶粘剂体系的研究现状，并对用上述三类胶粘剂所制ＲＡＣ的性能和胶粘剂的介电性能作了介绍，最后指出了在胶粘剂研究中应解决的主要问题。     

飞行器典型热密封结构

对航天飞机、X-38和X-51等飞行器的热密封结构进行了综合评述.分析了机身TPS、机身开口部位及控制面三个安装部位的热密封结构特点,综述了其热密封组件的研究历程和使用现状.     

Sealing reliability modeling of aviation seal based on interval uncertainty method and multidimensional response surface

Many variables affect the sealing performance, and their distribution characteristics are difficult to obtain with probabilistic methods owing to the high cost involved. Numerous problems in engineering are similar due to the appearance of small-sample parameters. In this study, the sealing reliability of an aviation seal was defined as the research object, and an interval uncertainty method and multidimensional response surface were proposed to calculate the sealing reliability.Based on this, we first analyzed the failure mechanism of the aviation seal and established a leakage rate model. Then, based on the non-probabilistic interval model, an interval uncertainty method was proposed to construct the analytical model. With reference to the limit state equation from the structural reliability theory, the multidimensional response surface was used for fast calculation.Then, we chose the single-cylinder gas steering gear used in aircraft as the case study, its sealing reliability in working and non-working statuses were calculated, and the results were verified with the actual maintenance records. By analyzing the sensitivity of some variables, we can improve the sealing reliability of the aviation seal by improving the surface roughness only if the cost allows.Finally, we consider that the method proposed in this study realizes the application of smallsample uncertainty analysis in reliability analysis, and could provide a feasible way to solve the similar problems in engineering with multidimensional and small-sample parameters.     

Coating deposition regularity depended on orientation difference in PS-PVD plasma jet

The YSZ coatings are prepared by the plasma spray-physical vapor deposition (PS-PVD) technology based on a specific experimental design. The structure, thickness and growth angle of YSZ coatings on the entire circumferential surface of the cylindrical sample are studied. The results indicated that the structure, thickness and deflection growth angle of YSZ coatings are related to the orientation of deposition location. The numerical simulation of the multiphase mixed fluid near the substrate is carried out and the deposition regularity and mechanism of YSZ coatings prepared by PS-PVD is deduced. The growth rate is related to the local characteristics of the plasma flow field, and is directly proportional to the field pressure and inversely proportional to the field velocity. The growth angle of the coating is generally affected by the flow direction of the plasma jet. Especially, the normal component of velocity vector, V_norm, mainly affects the speed at which the coating grows vertically upwards. The tangential component of velocity vector, V_tan, determines the degree that the coating growth direction deviates from the vertical direction. When V_tan ≠ 0, the coating forms a fine column with a certain deflection angle and finally develops into an oblique columnar structure.     

带有SiC涂层的C/C复合材料的氧化行为

采用包埋法在C/C复合材料表面制备了SiC高温防氧化涂层。利用SEM和XRD等方法对涂层的微观形貌和晶相组成进行了观察与分析,并对带涂层试样在室温~1 500℃范围内的氧化行为进行了研究。结果表明,涂层主要由β-SiC和少量的游离Si组成,涂层表面有裂纹存在,涂层与C/C复合材料基体结合良好,呈现犬牙状结合。在室温~1 500℃之间,带SiC涂层C/C复合材料的氧化行为可分为4个阶段,涂层在高温区具有较好的防氧化性能。     

热控涂层参数对卫星辐射特性的影响

为分析卫星红外和可见光双光谱辐射特性,分别建立了采用节点网络法求解卫星表面热控涂层温度和卫星辐射特性的计算模型,依据粗糙表面光散射理论计算了涂层表面对太阳、地球和地球反照辐射的吸收和反射。通过数值模拟,计算分析了卫星对地面的温度变化规律。最后,选择不同的热控涂层参数,获得了对卫星在红外和可见光波段的辐射特征的影响。     

指尖密封性能的模糊Nash平衡优化

针对工程应用中对指尖密封泄漏率和磨损率具有不同偏好要求的情况,通过集成Nash平衡博弈理论和模糊综合评判理论,建立了满足不同偏好要求的指尖密封性能模糊Nash平衡优化模型,研究了若干偏好要求条件下的指尖密封性能多目标优化问题.研究结果表明,与现有研究方法相比,提出的计算方法不仅有效地反映了工程中对各优化目标的不同偏好要求,而且大大减小了指尖密封性能多目标优化的决策工作量,提高了优化效率,其优化结果也较为理想.      

旋转诱导燃气入侵的数值模拟

在航空发动机涡轮级中,动盘的旋转会导致主流高温燃气从盘缘封严侵入转静盘腔系统.通过计算流体动力学方法对轴向封严结构下旋转诱导燃气入侵进行了研究,得到了在不同封严冷气流量下盘腔压力和封严间隙处径向速度的变化规律.分别计算基于质量和基于浓度定义的封严效率分布,并得到了相应最小封严流量.在不同旋转雷诺数下,用压力参数法估算了最小封严流量,所得结果与公开发表的经验关系式计算得出的一致.      

高转速袋型阻尼密封泄漏的特性

采用有限元分析和计算流体动力学耦合数值分析方法(FEA/CFD),研究了考虑转子系统由于高速旋转造成转子径向伸长效应时袋型阻尼密封的泄漏特性和流场形态.计算了密封间隙为0.13mm时,袋型阻尼密封试验件在3种压比、3种转速下的泄漏量,并与试验值和不考虑转子伸长效应的CFD数值模拟结果进行了比较,验证了所采用的FEA/CFD数值方法的可靠性(误差小于1.3%)和高转速下考虑转子伸长的必要性.研究了6种压比、6种转速下密封间隙为0.25mm的袋型阻尼密封的流场和泄漏量,分析了压比和转速对袋型阻尼密封泄漏特性的影响规律.结果表明:当压比大于0.26时,随压比的减小,袋型阻尼密封泄漏量逐渐增大;当压比减小到一定值时(π<0.26),泄漏流体的马赫数在最后一个密封齿间隙处达到1.0,即发生了堵塞,此时泄漏量达到与密封进口总压相对应的最大值;在高转速下,考虑和不考虑转子半径的伸长,密封泄漏量均随转速的增大而减小;在转子面周向马赫数大于0.35时,需要考虑转子半径伸长对泄漏量的影响.