固体推进剂定淬息距离凝相燃烧产物收集方法

含铝固体推进剂凝相燃烧产物对发动机的能量特性、热防护以及燃烧稳定性均有重要影响.为了排除燃烧过程中推进剂燃面退移造成的凝相燃烧产物淬息距离逐渐增大的影响,设计并建立了一套基于恒定淬息距离的凝相燃烧产物收集系统,并通过典型丁羟四组元推进剂凝相燃烧产物的收集和分析,对该收集方法进行了校验.结果表明,淬息距离恒定使得凝相燃烧...     

改进升力线理论和风洞试验结合的气动弹性修正方法

本文介绍了一种基于亚音速稳态定常流改进升力线理论与风洞试验相结合的大展弦比亚音速飞机的弹性翼面气动力分布载荷修正方法,设计目的是为了考虑具有大展弦比、弹性翼面结构的飞机翼面结构弹性变形对气动载荷分布的影响。     

用Nocilla模型计算卫星气动力系数和热流密度分布

本文用Nocilla粒子-表面作用模型计算卫星在运行轨道中整体气动力系数和星体表面热流密度分布,文中列出了详细计算公式和一个算例。     

Design and optimization of a novel electrically controlled high pressure fuel injection system for heavy fuel aircraft piston engine

The heavy fuel compression ignition engines are widely equipped as aircraft piston engines. The fuel injection system is one of the key technologies that determines the performance of engine. One of the main challenges is to precisely control the injected fuel quantity and flow rate in the presence of pressure fluctuation. This challenge is even more serious for heavy fuel. An original design for electrically controlled high pressure fuel injection system called Multi-Pumppressure-reservoirs fuel injection System(MPS) was demonstrated to reduce the pressure fluctuation and help keep injection stable. MPS was compared with an ordinary high pressure Common Rail fuel injection System(CRS). This work established one-dimensional AMESim and mathematical models for both CRS and MPS to study the effect of different structures and geometric parameters on the pressure fluctuations. The calculations show that the average fuel pressure fluctuation of MPS can be reduced by 57% for the crankshaft speed of 1900 r/min, and the pressure fluctuation before injection reduced by 100%. It is concluded that the pressure performance of MPS is less sensitive to pressure reservoir volume than that of CRS, and there is an opportunity for further volume reduction.     

基于效用价值驱动的旅客出行动力学研究与建模

为了探究交通体系中旅客出行行为的特征与机理,以某机场离港旅客的陆侧出行数据为研究对象,对旅客出行模式进行了统计。分析发现,旅客聚集行为具有强烈的阵发性,不同出行维度旅客群体的聚集时间间隔分布具有幂律特征,且幂指数和阵发性强度呈正相关关系。同时,研究认为旅客出行换乘决策是综合时间、费用、便捷舒适度、突发情况等多因素的期望实现,是一种基于效用价值驱动的人类行为。基于此构建了效用价值驱动模式下的旅客出行行为动力学模型,可输出幂指数为参数可调的幂律分布,且仿真输出和实证数据分析结果相吻合。      

地面燃气轮机单管燃烧室流量分配试验

对设计的100kW地面燃气轮机单管燃烧室空气流量分配进行了试验研究。在常压环境下采用堵孔法分别得到了旋流器、主燃孔和掺混孔的流量特性曲线,分析得到燃烧室不同结构的流量系数;试验研究了不同进口流量条件下燃烧室的流量分配,测量得到了燃烧室总压损失。研究发现:随着进口空气流量的增加,燃烧室的流量分配比例基本保持稳定,并且与燃烧室的设计空气比例基本吻合;随着燃烧室进口流量（雷诺数）的增加,旋流器、主燃孔和掺混孔的流量系数呈线性降低;随着进口流量（雷诺数）的增加,燃烧室总压损失逐渐增大;对主燃孔和掺混孔的流量特性测量中,两种测量方法得到的试验结果稍有差别,总体上看两种测量方法的试验结果较为接近。通过对比分析证明两种试验测量方法真实可靠,该研究结果可为100kW地面燃气轮机燃烧室的设计与优化提供依据。      

Evaluation method for helicopter maritime search and rescue response plan with uncertainty

Helicopter plays an increasingly significant role in Maritime Search and Rescue (MSAR), and it will perform MSAR mission based on response plans when an accident occurs. Thus the rationality of response plan determines the success of MSAR mission to a large extent. However, with the impact of many uncertainty factors, it is difficult to evaluate response plans comprehensively before performing them. Aiming at these problems, an evaluation framework of helicopter MSAR response plan named UMAD is proposed in this paper, which reveals the influence mechanism of uncertainty factors based on Multi-Agent method and analyzes the mission flow based on Discrete Event System (DEVS) method. Furthermore, the evaluation criterion and indicators of response plan are extracted from the aspects of safety and effectiveness. Meanwhile, the Monte Carlo method is adapted to calculate the probability distribution and robustness of response plan comprehensive result. Finally, in order to illustrate the validity of this method, it is discussed and verified by an application example of evaluating multiple response plans to the same MSAR scenario. The results show that this method can analyze the influence of uncertainty more systematically and optimize response plans more comprehensively.     

航天器多继电器线圈并联电路的可靠性研究

航天器配电系统中广泛采用多继电器线圈并联电路作为平台设备和负载的供电通路开关。文章从继电器互感效应入手,对多继电器线圈并联电路在指令发出、指令结束2 种工况下的电路可靠性进行了分析,结果表明目前常用的继电器线圈并联电路存在可靠性隐患。因此,针对隐患提出了在继电器线圈前串接二极管的电路可靠性优化方案。试验结果表明,优化后的电路形式可以有效提高电路的可靠性。     

中点箝位型光伏并网逆变器调制策略及效率对比

传统三电平中点箝位(Three-level neutral point clamped,3L-NPC)半桥逆变器在高压大功率条件下,由于开关器件损耗不均衡而使其容量受限,因此衍生了多种NPC型三电平半桥拓扑。为了优化选取NPC型拓扑及调制策略,对4种3L-NPC型拓扑(二极管NPC、有源式NPC、层叠式NPC及有源层叠式NPC)的调制策略及开关器件损耗分布进行了对比分析,并研制了一台5kW的NPC型统一实验平台,进行了效率测试。理论分析与实验结果表明:(1)根据零电平续流路径的配置不同,NPC型拓扑主要有4种调制策略;(2)选取合理的NPC型拓扑及调制策略,不仅可以均衡器件损耗,而且系统效率基本不变,为逆变器的扩容奠定了基础。     

Experimental study of a flush wall scramjet combustor equipped with strut/wall fuel injection

In this study a flush wall scramjet combustor is tested in a supersonic incoming air flow with the Mach number of 3 which is generated by an air vitiation heater producing the stagnation temperature of 1505 K. Using liquid kerosene as the fuel, the flame is stabilized by means of a centrally mounted O₂ pilot strut after being ignited by a plasma torch. During experimental measurements, the fuel is injected with a constant equivalence ratio of 0.8 according to specified strut/wall injection ratios, i.e., a portion of the fuel amount is injected from the strut while the rest is injected from the wall. The strut and wall injectors are arranged at the same axial position. The combustion performance and wall temperature gradients are evaluated with various fuel feeding ratios between the wall and the strut. Experimental results show, when the equivalence ratio is constant and the axial injection position is fixed, the combustion characteristics vary significantly with the strut/wall fuel feeding ratio, especially when this ratio is close to its lowest and highest limits. Among the four fuel feeding ratios examined, the strut only injection mode and the average distributed strut/wall injection mode show the best combustion performance. However, the strut/wall injection mode produces a smaller wall temperature gradient compared to the strut only injection mode, which is due to the significant film cooling effect caused by the wall injected liquid kerosene.