污染物沉积和热障涂层脱落对气膜冷却效率影响的数值研究

污染物沉积到有热障涂层的涡轮叶片上之后,会导致叶片表面状况的改变,进而影响气膜冷却效率。为分析影响规律,利用三维数值计算研究了3种典型情况下的气膜冷却特性:污染物沉积、热障涂层脱落及气膜孔堵塞,并得到了吹风比的影响规律。研究结果表明,平板气膜冷却吹风比为0.5时,冷却效果最佳;在发生沉积和堵塞后,气膜孔附近产生的反旋涡对会削弱沉积和堵塞后的气膜冷却效率,沉积高度增加会强化这种削弱效果;由于在沉积情况下高吹风比会诱导出正向旋涡使得气膜贴近壁面,因此随着吹风比增大,气膜冷却效果增强;因涂层脱落而在孔下游产生的裂纹在低吹风比时会降低冷却效率,高吹风比时改进冷却效果,使得最佳吹风比由0.5上升到0.7左右;气膜孔堵塞会降低冷却效率,使得气膜更易脱离壁面。      

再入钝锥体烧蚀热防护内部热响应的数值仿真

研究了烧蚀热防护系统内部热响应的计算模型和计算方法.采用碳化层-热解面-原始材料层模型,建立碳基材料内部热响应物理模型和数学模型,利用有限元法分析和计算再入目标热防护系统轴对称内部热响应.着重研究和分析了轴对称烧蚀过程中热解气体质量流率计算方法和传热机制.将热解气体与碳化层之间的对流换热处理为源项,通过保证刚度矩阵和形函数矩阵的正定对称性可以加速温度场计算收敛.计算表明:热解气体的质量流量主要由厚度方向构成,占80%以上;头部驻点附近最大烧蚀厚度接近10mm,需要采用抗烧蚀能力强的碳-碳材料,身部烧蚀量小于2mm,可以采用密度较小的碳-酚醛材料.      

RP-3航空煤油燃烧特性及其反应机理构建综述

目前耦合航空煤油多步燃烧反应机理的数值模拟计算已引起学者们的重视,燃烧反应机理的构建已成为研究热点。详细介绍了国内外关于航空煤油模拟替代燃料的选取、化学反应动力学模型构建和简化、着火延迟时间和层流燃烧速度等的实验规律。依据国外研究进展,指出了中国在国产RP-3航空煤油燃烧反应机理研究方面应从基础研究做起,全方位、多维、立体地合作开展相关研究,主要包括:国产RP-3航空煤油化学动力学模型的建立、低温高压工况条件下航空煤油与模拟替代燃料的基础实验研究与模型燃烧室研究,以期丰富相关研究成果,推进航空发动机的高质量发展。     

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...     

尖部喷气驱动旋转机翼地面试验装置的研制

为研究新概念旋转机翼飞机飞行动力学特性,掌握其直升机模式飞行时的气动特性,研制了一种尖部喷气驱动旋转机翼地面试验装置.介绍了该试验装置的组成、各组成部分的设计及为保证试验装置运行安全性而采取的一些措施.该装置采用高压气源作为旋转机翼的驱动动力,解决了旋转机翼的旋转、挥舞及偏转过程中的通气密封问题,通过测控系统进行试验数据的采集,操纵旋转机翼的总矩及周期变矩.     

Standing window of oblique detonation with pathological behaviour

Standing of an Oblique Detonation Wave (ODW) on a wedge within combustor is the prerequisite of thrust generation for ODW engine which is regarded as a novel and conceptual propulsion device with hypersonic flight Mach number. Usually a standing window of ODW is defined as the wedge angle ranged from the ODW detached angle from wedge (upper limit) to the angle that a Chapman-Jouguet (CJ) detonation occurs (lower limit). For pathological detonation cases, however, the CJ detonation cannot be achieved, and thus the lower limit of the standing window of ODW should be revisited. In present study, two types of reactions in hypersonic incoming flow that include the behavior of pathological detonation, that is, the single-step irreversible reaction with mole variation and the two-step irreversible reactions with exothermic process followed by endothermic process, have been used for studying standing behavior of ODW. The steady detonation polar analysis of ODW is carried out for both reaction systems. The results reveal that the reaction with more mole decrement and the reactions with stronger endothermic process show the pathological detonation feature and therefore modify the lower limit of standing window of ODW. Three equivalent parameters are proposed to quantitatively measure the standing window range of ODW from points of view of thermodynamics, Mach number of incoming flow and heat effect of reactions. It is found that the standing window of ODW is determined by the specific heat ratio, the overdrive degree of detonation and the endothermic level of the hypersonic incoming flow, regardless of whether the detonation is pathological or not.     

TATB、DATB热分解动力学和机理研究

采用DSC、PDSC、TG、TG-FTIR联用技术和热裂解原位快速扫描-FTIR联用技术,研究TATB和DATB热分解全过程,获得了TATB和DATB的热分解反应动力学参数,并提出TATB和DATB的热分解机理。研究结果表明,TATB和DATB热分解的初始过程存在苯并呋咱或苯并氧化呋咱中间产物。     

New concepts for the avoidance or utilisation of methane in life support systems

Due to high resupply costs, especially for long-duration stays in space habitats beyond low earth orbit, future manned space missions will require life support systems (LSS) with a high degree of regenerativity. Possible ways to overcome the waste of resources and to save on resupply mass are therefore of major interest for the development of next generation environmental control and life support systems.     

亚甲二醇二硝酸酯的构象和热解机理的理论研究

用量子化学中的ＳＣＦ－ＭＯ ＭＩＮＤＯ／３，ＭＮＤＯ，ＡＭ１和ＰＭ３方法计算研究了亚甲二醇二硝酸酯的几何构型和电子结构２，求得了ＭＧＤＮ的平衡几何构型。不同方法的计算结果均表明，标题物分子中两个ＯＮＯ２均为平面基团，且Ｏ－ＮＯ２键的Ｗｉｂｅｒｇ键级最淖分子中最弱的键，在分解时可能首先断裂；     

德士古水煤浆气化炉容器外壳材质

本文在国内现有的及正在建设的德士古水煤浆气化炉的基础上,对水煤浆气化炉容器外壳材质的选择进行简要的分析。