某发动机低频不稳定燃烧的消除

根据发动机热试车出现的低频不稳定燃烧现象，分析了产品的故障模式，建立了相关零组件模型。对相关零件进行了改进设计，消除了发动机低频不稳定燃烧现象。     

Progress of continuously rotating detonation engines

Continuously rotating detonation engine (CRDE) is a focus for concern in the field of aerospace propulsion. It has several advantages, including one-initiation, high thermal efficiency and simple structure. Due to these characteristics, it is expected to bring revolutionary advance-ments to aviation and aerospace propulsion systems and now has drawn much attention throughout the world. In this paper, an overview of the development of CRDE is given from several aspects:basic concepts, applications, experimental studies, numerical simulations, and so on. Representative results and outstanding contributions are summarized and the unresolved issues for further engi-neering applications of CRDE are provided.     

某型蒸发式稳定器气动及燃烧特性研究

为解决亚燃冲压发动机在高速低温来流条件下的可靠点火、火焰稳定和高效燃烧问题,对某型蒸发式火焰稳定器分别进行了冷态流场和燃烧流场的数值研究,并与常规V型火焰稳定器进行了对比分析。研究结果表明:在给定范围内,蒸发式稳定器随来流速度的增大,总压恢复系数和停留时间明显减小,回流区长度、回流率和燃烧效率变化不大;与相同槽宽的常规V型火焰稳定器相比,回流率明显减小,总压恢复系数、回流区长度和停留时间略有减小。蒸发式稳定器后部形成明显的回流区,且基本上不受外部主流流动的干扰,通过单独控制稳定器局部供油,可以使稳定器在最佳油气比下工作,有利于在高速来流条件下可靠工作。     

低温氢气排放过程数值模拟

以低温氢气安全排放为目的,采用数值模拟方法对低温氢气直接排放和燃烧排放的流场进行分析.流场仿真计算采用了标准双方程k-ε湍流模型和氢氧单步燃烧模型.研究参数包括氢排放压力、流量、温度和环境风速,评价指标为氢扩散范围和燃烧范围.计算结果表明：燃烧排放燃烧范围小于直接排放氢扩散范围;排放压力增加、流量增大和温度降低均会使氢扩散范围和燃烧范围变大.     

超临界环境下煤油和UDMH单滴燃烧现象

采用重活塞实验系统,对煤油和UDMH在超临界环境下的蒸发和燃烧现象进行了初步研究,结果表明:无论液态或者凝胶燃料,在超临界环境下均存在蒸发现象。在空气超临界环境下,煤油和UDMH均产生自燃现象。自燃呈现多点着火现象,类似于"森林火灾"模式,且持续时间较长。燃烧大致可分为蒸发、点火、燃烧前期和燃烧后期4个阶段。     

激波聚焦诱导气液两相爆震燃烧的数值模拟

对以激波聚焦和增加障碍物方式诱导煤油-空气气液两相爆震燃烧的过程进行了数值模拟.采用欧拉-拉格朗日方法建立了脉冲爆震发动机(PDE)中气液两相流的喷射、雾化、掺混过程.研究发现环形爆震波在爆震管凹腔内经过反射、汇聚后能够引燃可燃混合物.而在障碍物处,激波的反射和再反射聚焦能够形成高温高压点(2700K,25MPa),产生局部爆炸,有助于形成稳定的脉冲爆震燃烧(波面速度为1900m/s,温度为2 950K),有效地缩短由缓燃向爆震转变(DDT)距离至0.45m.     

A combined turbulent combustion model in studying a lean flameout process

A modification of the Zimont turbulent combustion model is presented; the modification makes it possible to describe processes in diffusion and homogeneous flame fronts as well as to take into account the influence of different factors that cause flame destabilization. The model is based on the equation for a reaction completeness extent (completeness of combustion). The model realization to simulate the premixed combustion is described and the modification of the turbulent combustion model is applied to simulate a process of flameout downstream of the flameholder.     

超声速燃烧实验研究(Ⅱ)

用电弧加热空气,对带有突扩台阶后扩张形,入口M_a=2.1和3.0的超声速燃烧室进行了实验研究,并对两种不同燃烧室长度、煤油和氢气在垂直和平行喷射下的燃烧状况作了比较。     

H2O2-PE固液火箭发动机低频不稳定燃烧研究

介绍了85％H2O2-PE固液火箭发动机的低频不稳定燃烧特征;应用发动机质量守恒方程对发动机低频耦合振荡燃烧现象进行了一维模拟,分析了氧化剂喷射压降对低频不稳定燃烧的影响。利用扰动分析确立了固液火箭发动机的稳定工作限。提出了抑制低频耦合振荡燃烧的方法。     

Initiation characteristics of oblique detonation waves from a finite wedge under argon dilution

In this paper, the flow field characteristics of Oblique Detonation Waves (ODWs) induced by a finite wedge under argon dilution are studied by solving the Euler equations with a detailed chemical model of hydrogen and air. First, the effects of the expansion waves, argon concentration, geometric parameters, and Mach number on the ODW are discussed. The results show that the changes of these parameters may make the oblique detonation not be initiated. Then, the ODW initiation criterion of the finite wedge is summarized, as the characteristic length of the induction zone L_C and the characteristic length of the oblique wedge L_W meet the condition L_C/L_W < 1, the initiation of the ODW occurs; otherwise, it does not occur. What’s more, the Constant Volume Combustion (CVC) theory is applied to study the characteristic length of induction zone. It is found that CVC theory is more suitable for the “smooth transition” type of ODW flow field, the theoretical and numerical characteristic length in induction regions are in good agreement. This work is of great significance for the design of oblique detonation engines for hypersonic vehicles.