不同大气状态对座舱盖玻璃温度的影响

对我国典型地区部分高空大气数据进行了统计分析,得出各个地区随高度变化的最高温度曲线和最低温度曲线,并与国际标准大气曲线进行对比,对我国实际大气情况进行了初步探讨;以典型飞参数据作为计算输入,比较了不同大气状态下座舱盖玻璃温度的变化。计算结果表明:不同大气状态下座舱盖玻璃温度计算结果存在着显著差别。研究的结果对于座舱盖强度计算和使用寿命的研究具有一定的参考价值。     

月球大气分子逃逸率的计算

文章从理论上计算了月球大气分子的逃逸率,解释了月球大气稀薄的原因。根据月岩和月壤放出的气体量与逃逸的气体量达到动态平衡的假定,说明了月球上大气密度昼夜的差异。     

损耗大气中惯性重力波的非线性相互作用方程及其初步讨论

根据弱相互作用理论,本文建立了损耗大气中极性重力波的非线性相互作用方程。这组方程在三个方面推广了前人的工作:考虑了波的空间传播;包含了粘滞产生的衰减;波谱可以是连续的。粘滞衰减率的大小与波的空间尺度以及传播方向有关。Coriolis力的引入使相互作用系数成为复量。根据这组方程,考察了惯性重力波的参量激发。结果表明:在共振条件满足时,主波存在一个阈值,阈值大小与次级波的损耗率成正比。当主波振幅大于这个阈值时,次级波将指数增长。在相互作用过程中,次级波的频率将发生变化,变化的大小与主波能量成正比。      

Search for methane on Mars: Observations,interpretation and future work

The detection of methane on Mars has been reported by three different teams in 2004. Two of them used ground-based high-resolution spectroscopy in the near infrared range. The third one used the Planetary Fourier Spectrometer aboard Mars Express. Among the data sets, two of them reported a mean CH₄ mixing ratio of 10 ppb. However, these are marginal detections, which should be considered as tentative. The third (ground-based) data set, unpublished so far, seems to show evidence for strong localized sources of CH₄, corresponding to mixing ratios as high as 250 ppb in some cases. However, the high values reported in 2003 were not confirmed by subsequent observations performed by the PFS instrument in 2004. In the absence of a refereed publication, it is difficult to judge if the high values are indeed correct. Assuming that they are, the lack of their confirmation by the PFS could have several explanations, including, among others, localized transient vents, or time variations in the methane destruction rate. A biogenic source was first suggested for the martian methane. However, later studies showed that an abiotic source such as hydrogeology can be just as effective. Further dedicated observations are obviously needed to firm up the detection and distribution of methane on Mars.     

基于标准k-ε模型的平衡大气边界层模拟

基于标准k-ε模型和FLUENT软件,采用适当的平均风和湍流特征量入口条件,同时在壁面处采用修正壁面函数边界条件,进行空流场的平衡大气边界层模拟.将流场中不同位置处的平均风廓线、湍动能及其粘性耗散等流动特征量的廓线进行对比.结果表明,采用标准k-ε模型结合修正壁面函数对气流流经粗糙度相同的壁面时,不同位置处流动特征量的廓线吻合程度均较高.研究提出对建筑绕流等问题模拟之前需进行空流场的平衡性进行分析,另对文中尚未解决的问题进行讨论并提出解决思路.     

Effect of Martian atmosphere on aerodynamic performance of supersonic parachute two-body systems

Supersonic flows around parachute two-body systems are numerically investigated by solving the compressible Navier-Stokes equations. In the present study, both rigid and flexible parachute models are considered, which comprise a capsule and a canopy. The objective of the present study is to investigate the effects of the Martian atmosphere on the unsteady flows produced by these parachute two-body models and the structural behavior of the flexible canopy. It was found that in the Martian atmosph...     

Comparison of methods for the determination of key reactions in chemical systems: Application to Titan’s atmosphere

A new paradigm is emerging in the field of photochemistry modeling in giant planets and Titan atmospheres. The emphasis is placed on the accurate predictions of the models and the quantification of their uncertainties. In order to improve photochemical models predictions, it is necessary to identify in chemical schemes the key reactions that should be studied in priority at conditions relevant to planetary atmospheres.     

风对弹射座椅救生性能的影响

 针对某型弹射座椅建立了考虑风速的弹射过程动力学模型。选取不同风速风向和不同弹射速度作为计算状态,对弹射救生过程进行数值仿真,根据仿真结果分析风对弹射座椅救生性能的影响。通过在低速和中速两个弹射速度下,前向风、侧向风和大气垂直运动对弹射座椅救生性能影响的分析可知:较大的逆风不但会降低伞衣充满的轨迹高度,而且会产生人伞系统的振荡和摇摆,对安全救生存在一定的影响;大气的垂直运动对弹射救生系统的救生性能影响最大,它直接影响到救生系统的纵向运动轨迹。研究结果表明:前向风、侧向风和大气垂直运动均会对弹射座椅的救生性能产生不利影响,在真实的弹射过程中必须考虑风速对弹射救生性能的影响。     

对流层大气折射误差的微波辐射计修正

目前,雷达的目标跟踪定位、卫星的测控定轨等对大气折射误差高精度修正的要求越来越高。针对传统大气折射误差修正方法的成本高、实时性差等问题,研究利用对水汽和液态水含量敏感的双通道微波辐射计测得的辐射亮温来反演大气折射率的方法。对微波辐射计的反演结果和探空数据的结果进行比较,计算不同海拔高度上反演的平均偏差和均方差,发现利用微波辐射计反演得到的折射率剖面与探空值吻合较好,验证了此方法的可行性。同时介绍了微波辐射计新的定标方法和微波辐射计对于水平不均匀大气的折射误差修正方法。     

航空发动机在高空台上模拟标准大气条件试验的性能研究

通过两种型号航空发动机在高空台上的H=0、M=0试验，研究了不同环境压力对发动机地面试验性能的影响。试验结果表明，对研究的发动机地面试验而言，当发动机风扇换算转速在93％-96％时，环境压力在70～90kPa之间得到的地面换算性能基本一致。即对研究的两种型号发动机H=0、M=0试验来说，可以通过70kPa环境压力下的地面试验来确定发动机在标准大气海平面静止条件下的性能。