纵向波纹隔热屏气膜孔流量系数的实验研究

针对加力燃烧室离散孔纵向波纹板结构隔热屏,通过改变次流雷诺数和出流比得到了波纹板上不同开孔位置处气膜孔的流量系数。实验结果表明,不同开孔位置处流量系数有很大差异;同一开孔位置处,对于长径比远小于1（L/D=0.17）的孔,气膜孔和次流通道的动量比对小孔流量系数有很大影响,尤其是在动量比较小的情况下;而在同一动量比下,单纯改变小孔雷诺数或次流通道雷诺数对流量系数影响不大。     

模拟扭矩载荷作用的涡轮盘低循环疲劳寿命试验

提出了在传统涡轮盘低循环疲劳试验件上施加扭矩的试验方案,以某型发动机涡轮盘为对象,组装和调试了某型全尺寸涡轮盘预扭试验件,完成了低循环疲劳试验.加扭涡轮盘低循环疲劳试验结果与涡轮盘在传统不加扭矩方法下的低循环疲劳试验表现出明显差异.试验结果表明,涡轮扭矩对涡轮盘-轴连接销钉孔区域疲劳寿命有重要影响.      

全覆盖气膜孔阵列方式对冷却特性的影响

运用标准k-ε湍流模型对不同吹风比下正菱形、长菱形和超长菱形三种气膜孔阵列方式的多孔全覆盖气膜冷却的气膜出流流场特性、气膜绝热冷却效率和气膜综合冷却效率进行了数值模拟对比研究.结果表明:气膜孔阵列超长菱形排布是较优的排布方案,在该排布方式下,气膜出流向主流的穿透相对较弱,气膜沿展向的覆盖率也较高,因而气膜绝热冷却效率相对最高;气膜孔排布方式对气膜综合冷却效率的影响规律与气膜绝热冷却效率的基本一致,超长菱形排布仍然是较优的排布方案.      

A question raised from the observation of dynamic cusp formation: When and where does particle acceleration occur?

We present observations of a C9.4 flare on 2002 June 2 in EUV (TRACE) and X-rays (RHESSI). The multiwavelength data reveal: (1) the involvement of a quadrupole magnetic configuration; (2) loop expansion and ribbon motion in the pre-impulsive phase; (3) gradual formation of a new compact loop with a long cusp at the top during the impulsive phase of the flare; (4) appearance of a large, twisted loop above the cusp expanding outward immediately after the hard X-ray peak; and (5) X-ray emission observed only from the new compact loop and the cusp. In particular, the gradual formation of an EUV cusp feature is very clear. The observations also reveal the timing of the cusp formation and particle acceleration: most of the impulsive hard X-rays (>25 keV) were emitted before the cusp was seen. This suggests that fast reconnection occurred during the restructuring of the magnetic configuration, resulting in more efficient particle acceleration, while the reconnection slowed after the cusp was completely formed and the magnetic geometry was stabilized. This observation is consistent with the observations obtained with Yohkoh/Soft X-ray Telescope (SXT) that soft X-ray cusp structures only appear after the major impulsive energy release in solar flares. These observations have important implications for the modeling of magnetic reconnection and particle acceleration.     

平行孔系中心距公差坐标换算

通过对平面尺寸链分析，应用马克劳林公式作近似计算和全微分近似全增量方法，导出了孔距公差坐标换算公式．最后通过实例对其换算结果进行了验证．完全符合设计要求。公式简明、实用、易掌握。可供设计、工艺和操作人员在相应的平行孔系中心距公差坐标计算中采用。具有一定的实际应用价值。     

X-rays from the first massive black holes

X-ray studies of high-redshift (z > 4) active galaxies have advanced substantially over the past few years, largely due to results from the new generation of X-ray observatories. As of this writing X-ray emission has been detected from nearly 60 high-redshift active galaxies. This paper reviews the observational results and their implications for models of the first massive black holes, and it discusses future prospects for the field.     

气膜孔结构对涡轮导叶端壁冷却效率的影响研究

对涡轮叶栅端壁上游4种气膜冷却结构模型进行了数值模拟,得出在不同吹风比情况下涡轮叶栅端壁的流动与换热特性。结果表明,无槽气膜孔冷气射流在孔下游与主流相互作用形成1对转动方向相反的耦合涡,主流被卷入耦合涡并冲击到了端壁,使得孔间壁温接近主流温度,气膜冷却效率很低;带槽气膜孔抑制了耦合涡的形成,冷却了孔间端壁,气膜冷却效率较高,而且,随着槽深度的增加,冷气的展向(Y向)宽度逐渐增加,扩大了冷气覆盖区域,提高了端壁气膜冷却效率。     

Studies of strong gravitational fields near super-massive black hole horizons with space missions

General relativity (GR) can be probed by several tests in the weak gravitational field limit. On the contrary, very poor information exists about GR tests in strong gravitational fields. Here, we focus on the interaction of light rays with the strong gravitational field of a massive black hole and show that relativistic images may form. Hence, we calculate the shapes of shadows (mirages) forming just near BH horizons and discuss the possibility to estimate the black hole parameters (mass, spin and charge) by future astrometric missions. In 2007, the Radioastron space telescope will be launched and it will allow to evaluate those parameters for the black hole hosted at the center of our Galaxy.     

基于双判定准则的航空发动机叶片缺陷孔洞的边界提取

航空发动机叶片缺陷孔洞的几何形状复杂、位置分布散乱且曲率变化明显,使用单一判定准则难以完整地提取其边界特征点.为实现叶片缺陷孔洞边界的精准提取和孔洞边界线的平滑拟合,提出了一种基于双判定准则的航空发动机叶片缺陷孔洞边界特征点的提取算法.该算法采用K–Dimension tree(K–D树)建立点云的空间拓扑结构,以采样...     

Progress Report on Insight-HXMT: China's First X-ray Astronomy Satellite

Insight-HXMT is China's first X-ray astronomy satellite. It was launched on 15 June 2017 and is currently in service smoothly. Insight-HXMT has been used to scan the Galactic plane repeatedly, making pointing observations to neutron stars and black holes, and monitor the whole sky continuously in the MeV band. Insight-HXMT is also very flexible in making ToO observations, with the response time from about 3 hours to within a day. So far more than 50 refereed publications have been made with data from its observations; many more publications have used the data or results of Insight-HXMT one way or another. The scientific impacts of Insight-HXMT have been growing rapidly since launch. We expect Insight-HXMT to continue to operate for several more years.