燃烧室钝体火焰稳定器吹熄特性的数值分析

火焰稳定器吹熄特性的研究过去均采用实验方法并归纳出经验公式。本文通过计算燃烧流场的稳态临界点来逐步逼近非稳态吹熄极限,提出了一种数值方法来近似预测钝体火焰稳定器的吹熄特性。     

水蒸气对非预混燃烧室NO_x排放数值模拟研究

为研究水蒸气的混入对实际工作条件下的涡轮发动机燃烧室流场及NOx排放分布影响,采用Laminar flamelet燃烧模型对不同水蒸气含量下的煤油燃烧进行三维数值模拟。湍流及燃烧模型采用DLR-A湍流非预混射流火焰模型实验进行校验。燃烧室的计算结果表明,水蒸气的混入会减少燃烧室高温火焰燃烧区的尺寸和温度,流场的构型变化不大。通过OH基的组分分布及含量变化分析可知,在本文计算参数范围内,水蒸气会促使燃烧反应向下游移动。在起飞工作条件下,水蒸气进入燃烧室时其组分稀释及热沉为主要作用,化学反应的促进燃烧放热相对较小。当水蒸气的质量分数达到15%时,可减少约95%的NOx排放量。     

Experimental and numerical studies of a lean-burn internally-staged combustor

A lean-burn internally-staged combustor for low emissions that can be used in civil avi-ation gas turbines is introduced in this paper. The main stage is designed and optimized in terms of fuel evaporation ratio, fuel/air pre-mixture uniformity, and particle residence time using commer-cial computational fluid dynamics （CFD） software. A single-module rectangular combustor is adopted in performance tests including lean ignition, lean blowout, combustion efficiency, emis-sions, and combustion oscillation using aviation kerosene. Furthermore, nitrogen oxides （NOx） emission is also predicted using CFD simulation to compare with test results. Under normal inlet temperature, this combustor can be ignited easily with normal and negative inlet pressures. The lean blowout fuel/air ratio （LBO FAR） at the idle condition is 0.0049. The fuel split proportions between the pilot and main stages are determined through balancing emissions, combustion efficiency, and combustion oscillation. Within the landing and take-off （LTO） cycle, this combustor enables 42%NOx reduction of the standard set by the 6th Committee on Aviation Environmental Protection （CAEP/6） with high combustion efficiency. The maximum board-band pressure oscillations of inlet air and fuel are below 1%of total pressure during steady-state operations at the LTO cycle specific conditions.     

一种涡卷弹簧分离螺母装置设计及仿真分析

航天器的连接与分离技术是航天运输系统中的关键技术,连接分离装置作为该技术领域的关键装置,一直是航天领域的重要研究内容。针对航天器连接与分离的要求,提出一种涡卷弹簧非火工分离螺母装置,并对装置进行结构设计。涡卷弹簧是装置的关键部分,直接影响涡卷弹簧分离螺母装置的承载和工作特性。对涡卷弹簧的张力和扭矩特性进行分析,并通过仿真分析研究涡卷弹簧分离螺母装置的工作特性。     

前置导叶对两种涡轮导向器及涡系结构的影响

为了考察导向叶片对实验涡轮导向器气动性能及涡系结构的影响,采用在实验叶栅前放置前置导叶的方法分别对原型和改型两种涡轮低压导向器进行了低速风洞实验。实验结果表明:增加前置导叶后,两种导向器的总损失分别比不加前置导叶时降低,前置导叶对上、下通道涡强度及位置的影响较大,并导致损失分布及其它气动参数的相应变化。但增加导叶后两种导向器总体性能差不变,仍是改型优于原型。     

用于JL—ZKR燃烧器的牛角锥体旋风除尘器的设计

这种除尘器是为了满足JL—ZKR燃烧器的需要而设计的。它的体积小,造价低。构造简单,使用方便。它的除尘效率可达80％左右。但其阻力比普通除尘器略高。     

同轴非稳腔凸镜的涡流管冷却及稳定性

横向激励大气压(Transversely excited atmospheric,TEA)CO2同轴非稳腔激光器凸镜因热积累发生变形,对输出光束质量影响显著。为了改善TEA CO2同轴非稳腔激光器输出光束质量,采用涡流管低温气流冷却凸镜。应用有限元方法模拟计算了涡流管低温气流冷却对凸镜镜面热变形的影响,计算结果表明,随着激光器工作时间的延续,涡流管冷却对TEACO2同轴非稳腔激光器凸镜热积累导致的变形有较为显著的改善。实验实时监测了单脉冲平均能量18.3 J,激光器工作频率3 Hz,连续运行300 s,的光束模式。没有涡流管冷却时衍付极限信数因子β值由3.52变化到6.94,采用涡流管冷却后,β值仅由3.50变化到3.88。结果表明,涡流管冷却对提高光束质量稳定性有明显效果。     

AVC流动与燃烧特性分析

本文应用三维数值模拟方法,研究了应用AVC概念设计的燃烧室流动和燃烧特性。研究结果表明：AVC的总压损失系数、燃烧效率、旋涡结构和燃烧稳定性以及污染物排放,受前后钝体形成的凹腔结构内的气流喷射位置、喷射角度和主气流当量比的影响,其中受凹腔结构内的气流喷射位置影响最大。     

Static aeroelastic analysis of very flexible wings based on non-planar vortex lattice method

A rapid and efficient method for static aeroelastic analysis of a flexible slender wing when considering the structural geometric nonlinearity has been developed in this paper. A non-planar vortex lattice method herein is used to compute the non-planar aerodynamics of flexible wings with large deformation. The finite element method is introduced for structural nonlinear statics analysis. The surface spline method is used for structure/aerodynamics coupling. The static aeroelastic characteristics of the wind tunnel model of a flexible wing are studied by the nonlinear method presented, and the nonlinear method is also evaluated by comparing the results with those obtained from two other methods and the wind tunnel test. The results indicate that the traditional linear method of static aeroelastic analysis is not applicable for cases with large deformation because it produces results that are not realistic. However, the nonlinear methodology, which involves combining the structure finite element method with the non-planar vortex lattice method, could be used to solve the aeroelastic deformation with considerable accuracy, which is in fair agreement with the test results. Moreover, the nonlinear finite element method could consider complex structures. The non-planar vortex lattice method has advantages in both the computational accuracy and efficiency. Consequently, the nonlinear method presented is suitable for the rapid and efficient analysis requirements of engineering practice. It could be used in the preliminary stage and also in the detailed stage of aircraft design.     

涡脱位置及温度对涡声效应压力振荡影响

为探索涡-声效应对固体火箭发动机中压力振荡特性的影响,基于VKI (Von Karman Institute for Fluid Dynamics)发动机,通过改变挡板位置与燃气温度,对旋涡脱落引起的压力振荡进行了大涡模拟数值研究.耦合分析表明:挡板位于速度波腹附近,压力振荡最为严重;旋涡能量在输运过程中易于被湍流耗散,靠近喷管的二阶速度波腹处旋涡脱落压力振幅明显高于其它位置.解耦分析表明:温度对旋涡脱落频率影响不大,当旋涡脱落频率与声振频率分离后,压力振幅显著下降.