一种基于温度参数的热层密度修正方法

热层大气的阻力效应是影响低轨航天器大量空间操作的重要因素, 尤其是经验密度模式, 其固有的至少15%的内符合误差已严重制约航天器轨道计算精度的提高. 针对广泛应用的经验密度模式, 选择物理背景简明、关联参数较少的JACCHIA71模式, 以地磁平静条件下的全球散逸层顶温度最小值T_c及125 km高度拐点温度T_x为对象, 建立密度相对于上述温度参数的条件方程, 推导密度相对于温度参数的解析偏导数, 并给出其最小二乘解. 同时, 利用CHAMP卫星数据对模式进行修正, 模式平均误差从40%降低至3%左右. 通过TG01飞行器的轨道预报比较, 修正前后轨道预报位置精度从2 km提升至1 km左右. 经过CHAMP卫星和TG01飞行器的实测数据检验, 验证了修正算法的正确性和有效性.      

厚膜铂电阻测温元件

厚膜铂电阻是80年代推出的新一代铂电阻测温元件。以铂浆料代替铂丝,用印刷工艺制成版图代替丝绕,用激光调值代替手工调值,用破璃浆料复层代替绝缘物封装。生产成本低,特性符合 IEC 标准,响应速度快,抗冲击、振动,可靠性高,用途广泛。本文综述这种测温元件的发展背景、结构特点、工艺、性能及应用前景。     

旋转盘腔轴向通流的压降和温升数值研究

为获得旋转雷诺数对盘腔轴向通流温升和压降的影响,对轴向通流雷诺数(Re_x)恒定为1.0′10^₅、旋转雷诺数(Re_w)在0~5.31′10^₆之间、绝热边界下的流动进行了数值模拟,从流场特征、盘面绝热温升以及轴向通流压降和温升等三个方面进行了分析。研究表明,旋转雷诺数对于盘腔内部和轴向通流的流动均具有显著影响;尽管是绝热盘面,但是由于高速旋转的黏性耗散作用引发盘腔内气流的温升,由温度差引起的浮升力对于盘腔内流动和盘面温度分布的影响也是不可忽略的;随旋转雷诺数增大,轴向通流出口温度相对进口温度的温升急剧增大,在旋转雷诺数小于2.5′10^₆时,轴向通流相对温升系数在0.01以内,当旋转雷诺数大于4.5′10^₆时,轴向通流相对温升系数达到0.04以上。     

Fatigue life prediction model of 2.5D woven composites at various temperatures

As one of the new structural layout in the family of woven composites, 2.5D Woven Composites(2.5D-WC) have recently attracted an increasing interest owing to its excellent properties, i.e. high specific strength and fatigue resistance, in the aerospace and automobile industry. Indepth understanding of the fatigue behavior of this material at un-ambient temperatures is critical for the engineering applications, especially in aero-engine field. Here, fatigue behavior of 2.5D-WC at different temperatures was numerically investigated based on the unit cell approach. Firstly, the unit cell model of 2.5D-WC was established using ANSYS software. Subsequently, the temperature-dependent fatigue life prediction model was built up. Finally, the fatigue lives alongside the damage evolution processes of 2.5D-WC at ambient temperature(20 ℃) and unambient temperature(180 ℃) were analyzed. The results show that numerical results are in good agreement with the relevant experimental results at 20 and 180 ℃. Fatigue behavior of 2.5D-WC is also sensitive to temperature, which is partially attributed to the mechanical properties of resin and the change of inclination angle of warp yarns. We hope that the proposed fatigue life prediction model and the findings could further promote the engineering application of 2.5D-WC, especially in aero-engine field.     

北京上空高分辨率气球探空观测的温度垂直波数谱

使用分辨率为10 m的温度剖面检查2.90～8.01 km和14.65～19.76 km高度范围内归一化温度扰动谱的谱特性,并且将它们与模式谱比较.结果表明,在波数9.8×10-4～2.5×10-2m-1范围内,对流层的垂直波数谱有约-1.9的平均谱斜率;低平流层的垂直波数谱有约-2.2的平均谱斜率.这两个平均谱斜率大大偏离了目前饱和谱模式和普适大气谱模式表示的-3.0和-2.4谱斜率,并且认为是目前气球测量中曾经观测到的最平谱斜率.在波数9.8×10-4～2.5×10-2m-1范围内,对流层和低平流层的平均谱振幅比饱和谱模式的谱振幅分别大24倍和5倍,这也与饱和谱模式以及目前文献中的观测结果有很大不同.这些较大平均谱振幅与最平的平均谱斜率一道共同表明,观测的温度谱并不遵循目前的饱和谱模式和普适大气谱模式.      

温度冲击试验对固体发动机喷管堵盖结构影响的仿真分析

温度冲击试验可模拟极端温度环境对固体发动机结构的影响。本文利用三维有限元方法,通过热-机耦合,分析了一种固体发动机喷管堵盖在温度冲击中的温度、应力和应变的变化情况。结果表明:温度冲击中,喷管堵盖内存在温差,最大可达46℃;存在内应力,在铝合金支撑件/EP密封件环形界面处最大,低温-50℃时达18.1 MPa,是堵盖最先破坏的位置;EP密封件是堵盖的最薄弱环节,粘接结构最大内应力11.6MPa,分离结构9.1 MPa;得出了温度冲击下,影响喷管堵盖结构完整性的因素,表明选用低模量和合适线胀系数的密封材料,采用常温成型方法,脱开密封件/支撑件间环形交界面,可有效降低密封件/支撑件的内应力;含GFM/EP/铝合金喷管的真实发动机温度冲击试验结果与预估结果吻合。     

A novel temperature-compensation method based on correlation analysis for multi-FOG INS

Aimed at improving the bias stability of Fiber-Optic Gyroscope (FOG)-based inertial navigation systems in environments of various ambient temperatures, a novel temperature-compensation method based on a correlation analysis of the same batch of FOGs is proposed. The empirical mode decomposition method was employed to filter the high-frequency noises of the FOGs. Then, the correlation information of the multiple FOGs was used to analyze the feasibility of the method. Eventually, the same residual error of the FOGs was compensated via the simple piecewise linear models. The experimental results indicate that excellent compensation effects for both high- and low-accuracy FOGs are achieved using the proposed method. Specifically, the accuracies of high-accuracy FOGs are improved by approximately 33.9%, 20%, and 31.2%, while those of low-accuracy FOGs are improved by approximately 39.1%, 20.8%, and 26.1%. The method exhibits the merits of simplicity, validity, and stability, and thus is expected to be widely used in engineering applications.     

基于EFPI-FBG结构的光纤复合传感器研究

研究了一种基于非本征型Fabry-Perot干涉仪(EFPI)和光纤Bragg光栅(FBG)串联结构构成的EFPI-FBG光纤复合传感器,用于实现对压力和温度信号的同步测量。传感器选用熔融石英作为压力敏感材料,利用飞秒激光焊接技术实现传感器探头结构的封装。对传感器的工作原理进行了分析,制作并封装传感器工程样机,搭建测试系统,对传感器的性能进行了灵敏度及交叉敏感性分析。结果表明,该传感器在0.8 MPa范围内的灵敏度约为-0.729μm/MPa,在50℃~200℃范围的温度灵敏度为0.009 nm/℃,传感器压力测量最大允许误差为±4.12%FS。该EFPI-FBG复合传感器有望应用于压力—温度双参数测量需求的技术领域。     

PGE/ Phenolic 的动态热解对温度场计算的影响

通过建立材料动态热解情况下的非稳态导热微分方程,研究了PGE/ Phenolic 的动态热解对温度 场计算的影响,并将理论计算值与地面试验的实测值进行了对比分析。结果表明,对PGE/ Phenolic 考虑动态 热解能有效修正温度场计算的精度,使理论计算值与实测值更为接近。     

高精度数字温度计替代标准水银温度计的探讨

用基于工业铂电阻的高精度数字温度计替代标准水银温度计，是当今温度计量的一个研究热点。迄今为止这类产品只能作为工作器具使用，其主要原因是对高精度数字温度计的长期稳定性研究还不充分。介绍了一款高精度数字温度计长达8年的稳定性研究成果，并和标准水银温度计比较，说明用高精度数字温度计替代标准水银温度计是完全可行的观点，同时提出一些具体建议。