几何代数域内的光流场改进算法

提山了一种新的光流场计算方法：首先,在几何代数域内推导了光流约束方程的新形式;然后,在速度场平滑的基础上,通过求解关于初值问题的热传导方程求解光流场;最后,给出光流场的数值解和仿真结果。实验证明此方法是有效的。     

冲压发动机伴随蒸发过程的两相流流场计算

为了计算固液混合式火箭冲压发动机补燃室内带有燃料液滴的流场,用块隐式法计算气相流场,用分离流连续介质模型计算颗粒相的流动与蒸发过程,在控制方程组的联合求荽中,采用特定的算法来体现颗粒相的质量守恒律与尺寸的变化。算例表明,迭代过程能够快速收敛,计算结果定性正确。     

具有复杂边界的火箭冲压发动机流场数值计算

针对实际复杂的补燃结构和计算边界,以块隐式法计算流场,用代数法生成计算网格,通过改变离散方程来处理三维定常Ｎ－Ｓ方程边界条件。算例表明,该方法正确可靠,迭代过程能够快速收敛。     

Flow field characteristics,mixing and emissions performance of a lab-scale rich-quench-lean trapped-vortex combustor utilizing a quench orifice plate combined with a bluff-body

In this study, the low emission combustion technology of Rich-Quench-Lean (RQL) has been applied in Trapped-Vortex Combustor (TVC), and the combinative RQL-TVC shows a promising low emissions performance. By utilizing a quench orifice plate combined with a bluff-body, a lab-scale RQL-TVC was designed. The flow fields of RQL-TVC were measured by 2-D PIV and predicted by 3-D numerical simulation. Flow structures, radial profiles of normalized mean axial velocity, turbulence intensity and mixing level of the quench zone were analyzed. Results reveal that the dual-vortex and the single-vortex flow patterns both exist in cavities and quench zone of RQL-TVC, and the turbulence intensity is strong in the quench zone with some reverse flows. The spiral vortex was discussed by 3-D streamlines and the detail flow structures of the quench zone were analyzed based on the numerical results. The mixing level of the quench zone was determined, and results show that the quench device enhances the mixing level compared with TVC. Combustion efficiency and emissions performance were investigated experimentally, and results demonstrate that RQL-TVC has relatively higher combustion efficiency and lower emission index of CO, UHC and NO_x than the same size lab-scale TVC in present work.     

液体火箭发动机燃烧室工作过程仿真软件──CAFILRE的设计与实现

描述了液体火箭发动机燃烧室内喷雾燃烧与流动过程仿真软件CAFILRE(Combus-tion and Flow in Liquid Rocket Engine）的结构和功能。CAFILRE程序是采用模块化方法编制和发展的二维通用软件，具有模拟发动机燃烧室内推进剂雾化过程、液雾蒸发过程、湍流混合与燃烧过程的能力。用此软件可以对发动机内部进行详细的性能分析和参数优化。     

国外燃烧诊断技术的新进展

对近十几年来国外燃烧流场参数的非接触式激光光学诊断技术的进展作了简要回顾和评述。     

Design and examination of a turboprop inlet with scavenge duct

The inlet with scavenge duct is an important part of turboprop aircraft engine. This type of inlet normally has a complex shape, of which the design is challenging and directly affects the flow field quality of the engine entrance and thus the engine performance. In this paper, the parametric design method of a turboprop aircraft inlet with scavenge duct is established by extracting and controlling the transition law of the critical characteristic parameters. The inlet’s performance and internal flow characteristics are examined by wind-tunnel experiment and numerical simulation. The results indicate that a flow tendency of winding up on both sides is formed due to the induction of the inlet profile, as well as a vortex pair on the back side of the power output shaft. The vortex pair dominates the pressure distortion index on the Aerodynamic Interface Plane (AIP). In addition, with the increase of freestream angle of attack, the total-pressure recovery coefficient of the inlet increases gradually while the total pressure distortion index decreases slightly. On the basis of the experimental results under different working conditions, the parametric design method proposed in this paper is feasible.     

弯曲壁面流动分离及再附的尺度解析模拟

为准确预测弯曲壁面发生的流动分离及再附现象,基于模拟应力混合思想构建了新的RANS/LES混合框架,涡黏系数和湍动能耗散项中的长度尺度同步切换、涡解析区动态确定亚过滤尺度模型系数、采用混合过滤尺度匹配动态模型,并据此构造了k-ω基动态应力混合模型。首先利用槽道湍流检验了基准的亚过滤尺度模型和近壁RANS模型,前者解析获得了正确的湍流脉动近壁行为和相干结构,后者以很小代价捕捉到了雷诺应力分量的各向异性和松弛效应。随后利用周期性山算例考核了动态应力混合模型对分离再附湍流的预测精度,并与DDES,IDDES及SAS模型进行了对比。结果表明,三项改进使得动态应力混合模型具有近壁模拟能力且不存在对数律不匹配问题,涡解析能力优于DES类隐含的准代数模型,能够更好地捕捉压力梯度诱导的流动分离和再附,获得更为准确的壁面剪切应力、摩擦系数、压力系数、回流区,分离剪切层相干结构的分辨率更高。     

涡轮叶片内部微小V肋-凹陷涡复合冷却流动与传热数值模拟

为强化航空发动机涡轮叶片内冷通道传热性能,针对带有微小V肋-凹陷涡高效复合冷却结构矩形通道,采用Abe Kondoh Nagano （AKN） k-ε湍流模型数值模拟研究了肋高与凹陷深度组合对流动传热特性的影响机理。结果表明,当凹陷深度一定,复合结构的强化换热效果随肋高增加而增加,3mm肋高复合结构的传热相比纯凹陷提高了87.1%;当肋高一定,传热随凹陷深度增加先增强后基本保持不变,6mm深凹陷复合结构相比纯V肋提高了52.8%。通过在凹陷上游布置V肋,增强了越过V肋冲入凹陷内流体的湍动能,从而使凹陷前部回流区减小;同时来自微小V肋的涡流与凹陷内部的涡流相互作用,增强了整个流场的动量和热量输运,使通道换热均匀,并相较纯凹陷或纯V肋结构均有显著提升。     

弹射动力系统燃气发生器流热固耦合数值研究

为了判断弹射动力系统燃气发生器工作的安全性,需要预示工作过程中燃气发生器壳体的力学响应。基于软件CFX和ANSYS,建立了燃气发生器复合结构流热固耦合仿真模型。对燃气发生器内流场和结构温度场进行流热耦合计算,并将壳体温度场计算结果与试验数据进行对比,再将算得的燃气压强分布与结构温度场分布导入ANSYS以计算结构的力学响应。计算结果表明,燃气发生器工作过程中,直筒段最高温度点位于直筒段与后封头连接的绝热层缝隙处,后封头最高温度点位于后封头与喉衬配合部位的上游端。结构最高温度值仅354K,说明热防护良好;直筒段和后封头壳体主体区域应力安全系数>3,满足设计要求,而在法兰附近圆角过渡处外壁存在应力集中,最大应力处安全系数降为1.13,燃气发生器壳体仍处于安全状态,但存在安全裕度显著降低的风险。