航空涡轮发动机燃烧室内流场的PIV测量

设计了一种基于旋风分离原理的高压粒子发生器，并成功应用于高压状态下的航空涡轮发动机燃烧室内流场的PIV（粒子图像测速法）测量.在氢氧燃烧加热来流温度为813K、燃烧室压力为2.78MPa条件下，应用PIV技术开展了航空涡轮发动机单头部燃烧室复杂内流场测量研究，实现了高温高压条件下强旋流、强扰流、宽速域流场的PIV测量，获得了接近燃烧室工作压力工况下的流场速度和流场精细结构.结果表明:该型燃烧室内流场存在多处旋涡结构，形成回流区；流场旋流作用强，横截面流场存在顺时针大涡；主燃孔射流和掺混孔射流作用明显，射流穿透深度较大，对流场结构影响显著；高温高压状态下，流场结构与常温中压状态类似.      

离心力场对内燃波转子火焰传播特性的影响

为了揭示离心力对内燃波转子火焰传播特性的影响，建立了内燃波转子燃烧过程的简化模型，数值模拟了不同离心力场强度下波转子通道内的燃烧过程。研究结果表明，离心力只在一定范围内对火焰传播起到加速作用，且这种影响与预混气当量油气比Φ有关，当Φ=1.0时，作用范围为［0～250g］，在Φ=0.6，0.8时，作用范围为［0～700g］；离心力场对内燃波转子火焰传播特性的影响机制是导致火焰锋面变形，进而引起火焰传播速度变化。     

Experimental study on flow excursion instability of supercritical hydrocarbon fuel in scramjet regenerative cooling parallel channels

Flow instability of supercritical hydrocarbon fuel is a crucial issue in scramjet regenerative cooling structure. In this study, flow excursion instability and flow distribution in parallel tubes were experimentally studied for supercritical fluids. Two types of flow excursion occur in a single tube. Type I and Type II excursions, and they are corresponding to decreasing and increasing flow rate respectively. They can trigger flow maldistribution between parallel tubes and the hysteresis phenomenon of flow distribution. The effects of system parameters, including inlet temperature, system pressure, and heat flux, on flow distribution were analyzed. In addition, the relationship between flow excursion and the pseudo-critical interval proposed in the literature was established according to the heated tube outlet temperature at the onset of flow instability. Finally, the flow excursion instability boundary was obtained using two dimensionless parameters. These experimental results can provide helpful insight on the mechanism of Scramjet regenerative cooling.     

轴向三级旋流燃烧室流场结构大涡模拟

为深入了解真实航空发动机燃烧室内部复杂流场结构，在自有CFD平台上采用动态亚网格模型对一种轴向3级旋流燃烧室的单个头部矩形试验模型0.5MPa下冷态流场结构进行了LES(大涡模拟).为避免试验模型简化误差，对包括火焰筒上约2000个气膜孔在内的燃烧室所有精细结构进行了完全仿真.计算模拟了燃烧室内复杂流场从静止启动到统计定常状态的完整非定常发展过程，成功捕捉到主旋流与横向对冲射流相互影响作用及涡旋破碎等细观结构，获得的测点湍动能谱与湍流经典理论中惯性子区-5/3规律一致，LES时间平均流场结构与已有PIV（particle image velocimetry）试验结果吻合，表明所建立的高仿真网格与LES方法可进一步用于真实航空发动机环形燃烧室流场数值模拟.      

喷注方案对圆形超燃冲压发动机性能的影响研究

在飞行马赫数Ma=6，总当量比为1.0条件下，采用三维数值模拟研究了不同喷注位置煤油当量比分布对双凹腔圆形发动机推力性能和壁面热流的影响。喷注位置包括支板壁面喷注K1，隔离段出口壁面喷注K2，第一凹腔尾缘壁面喷注K3以及第一扩张段壁面喷注K4。结果表明，K1注油当量比大小直接影响燃烧室内的燃烧模态和流道中心燃烧。为了保证发动机推力性能，K1注油须达到一定量，促使流道燃烧处于亚燃模态，且流道内具有较强的中心燃烧。为优化发动机壁面热流环境，剩余燃料需要在K2，K3和K4分散注入。K2和K3注油当量比大小同时影响第一凹腔燃烧性能，其中K2注油当量比降低，推力性能下降，但壁面热流性能提高，而适当增加K3喷注煤油，有利于提高推力性能。增加K4注油，第二凹腔及其之后流道区域燃烧增强，发动机推力性能和热流性能均提高。通过分析各注油位不同当量比分布对发动机力热性能的影响规律，最终获得了力热性能较优的注油当量比分配方案，此时K1～K4注油当量比大小依次为0.6，0.1，0.1，0.2。     

Effect of baffle injectors on the first-order tangential acoustic mode in a cylindrical combustor

Combustion instability is a very important issue in the development of the propulsion systems used in aerospace. It is very important to associate the high frequency combustion instabilities with the acoustic characteristics of the combustion chamber. In this paper, the effects of various baffle injectors which were installed on the injector faceplate on the first-order tangential acoustic mode were investigated theoretically and experimentally. The effects of the gap between adjacent injectors on the first-order tangential acoustic mode in a cylindrical chamber were considered. The acoustic admittance of the injectors was derived. The results showed that the amplitude and frequency of the first-order tangential acoustic mode increase with the increase in the gap between adjacent injectors, but decrease with the increase in the number and height of the baffles. The baffle injectors have a greater influence on the amplitude and frequency of the first-order tangential acoustic mode than the baffle blades.     

Effect of injection scheme on asymmetric phenomenon in rectangular and circular scramjets

The asymmetric separation has a crucial effect on the performance of the scramjet. In this study, the asymmetric separation and combustion in both rectangular and circular scramjets are investigated numerically, and the effect of injection scheme is analyzed. The characteristics of the flow field are analyzed based on sufficient code verification. In the rectangular scramjet, the separation tends to occur in the corner due to the corner boundary-layer effect. The separation is asymmetric and only two corners have serious separation. The fuel penetration depth in the separation zone increases and the combustion is intensified. When the injection scheme is uniform, both the combustion and separation become weak. In the circular scramjet, the separation and combustion are basically axisymmetric in the scramjet with one-row injection scheme. The asymmetric combustion becomes obvious in cases with multi-row injection scheme. When the injection orifices distribute intensively on the top and bottom sides, the strongest and weakest separations occur near these two sides respectively. When the distribution of orifices becomes uniform, the direction of separation cannot be predicted. For multi-row cases, the nonuniform injection scheme could result in violent combustion and asymmetric flow structures compared with the uniform injection scheme.     

用于光纤F-P声压传感器的直流补偿解调技术研究

提出了一种改进的双腔直流补偿技术，用于解调非本征法布里-珀罗干涉(EFPI)光纤传感器，以消除腔长差与入射光波长相匹配的要求。通过消除直流分量和校准信号相位，可以从具有任意相位差的原始信号中获 得两路正交信号。通过理论仿真，制作了具有不同腔长差的EFPI光纤传感器，对所提出的方法进行了试验验证。 结果表明，该方法在解调双 F P腔 EFPI传感器时，不需要保证初始相位差恒定，且对腔长漂移不敏感，具有良好的 稳定性和实用价值。     

燃气分析法在高温升全环燃烧室 出口温度场试验中的应用

为了给某型高温升全环燃烧室的出口温度分布改进优化提供技术支持,采用燃气分析法和热电偶法2种测量方法测量出口温度场。燃气分析法通过2支5点非混合式取样器随旋转机构旋转1 80°,采集燃烧室出口600点样气,测量CO_2和CO_2种组分的体积分数进而计算燃气温度。在油气比0.03状态下,燃气分析法与热电偶法测量的燃烧室出口温度分布基本一致,在油气比0.037状态下,燃气分析法测到的热点温度达到2285 K,经误差分析得出CO_2和燃料热值的测量偏差对燃气分析法的温度测量影响较大,采用的燃气分析法测温系统总误差在1%以内。研究结果表明:燃气分析法是1种具有较高测试精度、可靠的高温测试技术。     

超燃燃烧室悬臂斜坡喷注器/凹腔组合结构研究

超燃燃烧室中燃料的掺混强化问题备受关注,为了优化悬臂斜坡喷注器/凹腔组合结构在超燃燃烧室中的流场特性,运用数值模拟方法对悬臂斜坡喷注器/凹腔组合结构的冷、热流场进行研究,对比分析有无凹腔结构、悬臂斜坡喷注器/凹腔不同位置组合对流场特性的影响。结果表明:随着组合位置距离的增大,凹腔的稳定燃烧作用变强,但不同的组合位置会带来燃烧室不同的燃料掺混效果和燃烧特性;综合考虑,组合距离h=30mm虽然总压损失较大,但却拥有更强的燃料掺混效果和更大的燃烧效率收益,流场特性最优。