绕任意轴旋转的方形截面大曲率弯管流动特性的研究

利用数值计算的方法研究了绕任意轴旋转的方形截面大曲率弯管内的粘性流动情况，分析了在不同人口距离处离心力和科氏力共同作用下的二次流动、轴向主流的发展变化情况。计算结果表明：当F接近-1时，二次流呈现6-涡结构；F≥0时流场内流场随，变化依次呈现2涡-4涡-6涡-4涡-2涡-4涡结构，并且随着F的增大，流动在距入口更近的地方便达到充分发展；F=4．0流场呈现6-涡结构时，只有两个轴向速度极值区，分别位于靠近管道外侧的上下角处。     

高位垂直进气径向出流旋转盘腔风阻效应的实验

用实验的方法对高位垂直进气转静系旋转盘的风阻效应进行了研究,研究结果表明:转盘无量纲力矩系数随着旋转雷诺数的增加而减小;转盘无量纲力矩系数随着流量系数的增加而增加;且与冷却的具体结构有关;在高旋转雷诺数时,转盘无量纲力矩系数小于自由盘无量纲力矩系数;当流量为0时,无量纲力矩系数的数值全部小于自由盘之值.     

超精密车床主轴回转精度动态测试机构的研制

介绍一种超精密车床主轴回转误差运动的动态测试机械装置,该装置操作调试方便,测试效果良好.     

旋转条件下固体火箭发动机燃烧室气-固两相湍流流动数值模拟

以不可压Ｎ－Ｓ方程为基础，在旋转相对坐标系中，采用贴体坐标和ＳＩＭＰＬＥ法，对给定结构的旋转固体火箭发动机燃烧室诬蔑一中气－固两相湍流流动进行了数值模拟。不同时刻燃烧情况的计算结果表明：旋转对固体火箭发动机燃烧室燃气流动结构的影响随着燃烧肉厚而退移而显著增强；在发动机药柱的前翼燃烧消失后，前封头开口区域的气－固两相切向涡开始为得热烈，切向涡的分布呈现Ｒａｎｋｉｎｅ特点，在发动机前开口区域涡的固synw     

Spatial fragmentation of solar flare plasma and beams

The observational and theoretical arguments for spatial fragmentation of the bulk of the thermal and non-thermal components of solar flare plasma are summarised. Observational aspects considered include XUV filling factors, EUV centre to limb variations, andH impact polarisation. Theoretical points addressed are the high flare inductance and beam/return current closure at the acceleration site.A high degree of beam/plasma filamentation implies strong transverse temperature gradients so that cross-field conduction must be included in energy transport modelling. Preliminary results are described for a simple two-component model.     

曲梁弹性波的传播

用特征线法求出了脉冲载荷作用下的控制曲梁运动的Ｍｏｒｌｅｙ方程的数值解，并用Ｐｌａｓｓ的直梁结果验证了曲率趋于零的极限情形，应用性地研究了曲梁中部受冲击载荷作用的弹性波传播问题，计算结果表明：该数值计算方法简便易行、效率高、有良好的收敛性和稳定性。     

轴流超跨音高载荷对转涡轮气动特性分析

对转涡轮可有效提高涡轮级效率、减轻涡轮重量、缩短涡轮轴向尺寸和减少涡轮零部件数目.分析了轴流式超跨音高载荷低压无导叶对转涡轮基本气动特性,推导了效率公式,阐述了对转涡轮在减少设计自由度后,其高低压转子气动参数间相互制约关系.研究结果表明:为合理分配对转涡轮高低压转子轮缘功,气动设计参数调整的结果使高压涡轮载荷系数增加,气流转折角变大,气动特征参数明显高于传统同转涡轮.     

T cell regulation in microgravity – The current knowledge from in vitro experiments conducted in space,parabolic flights and ground-based facilities

Dating back to the Apollo and Skylab missions, it has been reported that astronauts suffered from bacterial and viral infections during space flight or after returning to Earth. Blood analyses revealed strongly reduced capability of human lymphocytes to become active upon mitogenic stimulation. Since then, a large number of in vitro studies on human immune cells have been conducted in space, in parabolic flights, and in ground-based facilities. It became obvious that microgravity affects cell morphology and important cellular functions. Observed changes include cell proliferation, the cytoskeleton, signal transduction and gene expression. This review gives an overview of the current knowledge of T cell regulation under altered gravity conditions obtained by in vitro studies with special emphasis on the cell culture conditions used. We propose that future in vitro experiments should follow rigorous standardized cell culture conditions, which allows better comparison of the results obtained in different flight- and ground-based experiment platforms.     

Modeling PSBL high speed ion beams observed by Cluster and Double Star

On October 8, 2004, the Cluster and Double Star spacecraft crossed the near-Earth (12–19 R_E) magnetotail neutral sheet during the recovery phase of a small, isolated substorm. Although they were separated in distance by ∼7 R_E and in time by ∼30 min, both Cluster and Double Star observed steady, but highly structured Earthward moving >1000 km/s high speed H⁺ beams in the PSBL. This paper utilizes a global magnetohydrodynamic (MHD) simulation driven by Wind spacecraft solar wind input to model the large-scale structure of the PSBL and large-scale kinetic (LSK) particle tracing calculations to investigate the similarities and differences in the properties of the observed beams. This study finds that the large-scale shape of the PSBL is determined by the MHD configuration. On smaller scales, the LSK calculations, in good qualitative agreement with both Cluster and Double Star observations, demonstrated that the PSBL is highly structured in both time and space, on time intervals of less than 2 min, and spatial distances of the order of 0.2–0.5 R_E. This picture of the PSBL is different from the ordered and structured region previously reported in observations.