Effects of chemical energy accommodation on nonequilibrium flow and heat transfer to a catalytic wall

The accurate prediction of the aeroheating performance of hypersonic vehicles requires more detailed modeling of the catalysis process, rather than merely employing a catalytic coefficient. In this paper, the theoretical modeling, as well as the direct simulation Monte Carlo method,is used to preliminarily study the incomplete chemical energy accommodation effects, that is, only a part of the potential energy released in the heterogenous recombination reaction is transferred to the surface, whil...     

A multi-parameter model of heat treatment process for soft magnetic materials on performance of HSERs

Material properties play an important role in the performance of electromagnetic mechanism. For an aeronautic Hermetically-Sealed Electromagnetic Relay (HSER), more than 50% parts are made of soft magnetic materials. Therefore, the performance of soft magnetic materials directly determines the static and dynamic characteristics of the HSER. Based on the theory of crystal recrystallization, this paper analyzes cold extrusion and heat treatment in the processing of soft magnetic materials, simulates the grain change process of an armature at different heat treatment temperatures, establishes a correlation model of temperature, grain size, and magnetic energy, and verifies results by scanning electron microscopy. Results of heat treatment temperatures from 800 °C to 920 °C are obtained and compared. A sample soft magnetic material after heat treatment at different temperatures has the largest difference in the initial magnetization range, up to 22%. In order to verify the fluctuation of the overall output characteristics of an HSER caused by the difference between soft magnetic materials, a static and dynamic analysis model of a typical HSER is established, and the accuracy of the model is verified by a set of actual test system. The difference of dynamic characteristics under different heat treatment temperatures is nearly 3%.     

Experimental study on dynamic behavior of mechanically pumped two-phase loop with a novel accumulator in simulated space environment

Mechanically pumped two-phase loop (MPTL) which is a prominent two-phase heat transfer technology presents a promising prospect in thermal control for space payload. However, transient behavior of MPTL caused by phase-change and heat sources load-on/off in simulated space environment is rarely reported. In the present study, one MPTL setup was designed and constructed, and experimentally studied. Particularly, a novel two-phase thermally-controlled accumulator integrated with passive cooling measure and three capillary structures was designed as the temperature-control device. Dynamic behavior of the start-up, temperature control, and temperature adjustment were monitored; meanwhile, thermodynamic behavior within the proposed accumulator, the operating behavior as well as the heat and mass transfer behavior between the main loop and the accumulator were revealed. The results show that the fluid management function of the capillary structures for the novel accumulator is verified. The working point of the MPTL system can be adjusted by changing the temperature control point of the accumulator and it is little influenced by external heat flux and heat sources on/off. Pressure-drop oscillations which are manifested as fluctuations of temperature and pressure can be observed after phase changing due to the compressible volume within the accumulator and the negative-slope portion of the internal pressure.     

热处理制度对激光增材制造TA15钛合金力学性能的影响

进行了普通退火态和双重退火态激光增材制造TA15钛合金显微组织观察和力学性能试验.试验结果表明:普通退火态为细片层α+β超细网篮组织,双重退火态为端部带根须状形貌的初生α相+超细β转变组织构成的特种双态组织;普通退火态激光增材制造TA15钛合金极限强度、屈服强度和疲劳极限均优于双重退火态;双重退火态激光增材制造TA15...     

A refined design method for precoolers with consideration of multi-parameter variations based on low-dimensional analysis

The precooler is a distinctive component of precooled air-breathing engines but constitutes a challenge to conventional thermal design methods. The latter are based upon assumptions that often reveal to be limited for precooler design. In this paper, a refined design method considering the variations of fluid thermophysical properties, flow area and thermal parameters distortion,was proposed to remediate their limitations. Firstly, the precooler was discretized into a fixed number of sub-microtu...     

载人航天器舱内辐射环境及剂量分析

构建载人航天器模型,利用Geant4软件计算了银河宇宙射线中的质子穿过载人航天器后在水模体中的总吸收剂量以及次级粒子吸收剂量,并且统计了不同种类的次级粒子在水模体中的总数量分布。计算结果表明,次级粒子引起的辐射剂量所占比例为50%,且二次电子总数量达到了10~7量级。     

大型固体发动机旋转试车头部热防护工程分析

介绍了与ＬＭ－２Ｆ运载火箭配套的固体近地点变轨发动机的结构参数和在地面旋转试车时出现的头部烧穿故障。     

一种再入飞行器结构的热流载荷反演方法

提出了一种基于共轭梯度法的再入飞行器热流载荷反演方法.以一维结构为例验证反演方法的有效性,并分析了材料温变热物性参数和传感器测量误差对反演精度的影响;进而针对热防护结构和返回舱结构开展了热流载荷反演分析.结果表明:本文方法能有效地反演热防护结构和返回舱结构的热流载荷;考虑材料的温变热物性参数会使得反演过程存在非线性因素...     

热处理对650 ℃短时用Ti650板材显微组织和力学性能的影响

研制了一种Ti-Al—Sn—Zr—Mo—W—Si系650℃短时应用的Ti650钛合金板材。采用光学显微镜和扫描电镜分析了不同的热处理制度对11mm和2mm厚两种规格板材的显微组织的影响，并测试了力学性能。结果表明：经三重热处理后，Ti650钛合金拥有良好的室温、650℃拉伸性能和室温冲击性能。     

小型固体火箭发动机燃烧室绝热层成型工艺研究

通过绝热层胶料及共浇注体的性能测试和对燃烧室绝热层的各种试验，探讨了配心压注整体成型工艺条件，分析了该工艺的关键技术和控制绝热层表面质量的方法，考核了绝热层的设计和使用性能。实验结果表明：该工艺生产的燃烧室绝热层性能良好、外观光亮、质量稳定、合格率达到100％。