Large-Scale Streamwise Vortices in the Supersonic Part of a Permeable Nozzle

Large-scale streamwise vortices in the vicinity of a perforated wall in the supersonic part of the nozzle are studied. The governing effect of gas inflow through a perforated wall on origination and parameters of streamwise vortices is experimentally established.__________Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 46, No. 5, pp. 68–75, September–October, 2005.     

任意长度喷管型面设计方法在气动激光器喷管设计中的应用

 将一种新的任意长度喷管型面设计（ALN）方法应用于气动激光器喷管型面设计,在相同的喷管出口设计马赫数、喷管喉部高度及喷管扩张段长度条件下,设计了4条ALN方法喷管型面,并和一条最短长度（MLN）喷管型面作对比,采用2维气动激光器增益场仿真方法对5个喷管的小信号增益场进行仿真。计算结果表明:ALN方法可以有效地实现增益场分布的控制,选择合理的设计参数得到的喷管长度比MLN喷管更短,小信号增益更大。     

电磁铸轧铸嘴支撑面板热应力分析和结构改进

利用ANSYS有限元分析软件建立了铸嘴支撑面板温度-应力耦合分析的三维有限元计算模型．为了优化面板内的应力分布。减小热位移，特别是与铸嘴平面稳定性直接相关联的竖直方向热位移，对面板进行了结构改进，并对实际工况下面板的热应力分布进行了计算研究．研究结果表明：面板内存在显著的热应力，应力集中现象明显；面板总体上出现了较大的热位移，特别是在竖直方向，热位移量为最大，导致面板因变形过大失效．改进后面板的热应力在总体数值上有所升高，但应力集中现象有所改善，在竖直方向的热位移量已显著减小，能很好地满足电磁铸轧的工艺要求．     

On the choice of approximations in direct problems of nozzle design

Two problems are considered: the design of a supersonic nozzle with a uniform exit characteristic and the design of a subsonic nozzle part with a plane (straight) sonic line in the minimum cross section. It is shown how the choice of a nozzle profile approximation affects the direct solutions to variational gas dynamics problems. The nozzle profile is described by polynomials or splines (quadratic, cubic, rational). The varied variables are the profile’s expansion coefficients in terms of basis functions or the parameters to be interpolated. It is shown that a priori information on the monotonicity of the desired profile improves the efficiency of the solution.     

高压SF6断路器喷口烧蚀特性的模拟研究

对SF6断路器喷口的电弧烧蚀特性进行了模拟研究。根据理论模型和模拟计算结果发现，添加质量分数为1%-5%的填料，可以控制喷口对电弧能量的吸收，从而有效地改善喷口耐电弧烧蚀性能，当填料粒度大于10цm时，可延长喷口起始烧蚀时间。为提高喷口的耐电弧性能、延长SF6断路器的电寿命提供了理论依据。     

喷口电弧的微分-积分模型

本文在能量守恒、质量守恒、动量守恒、欧姆定律的基础上,提出了一种描述气流中喷口电弧特性的新的物理数学模型—微分-积分模型。由于这一模型既具有积分模型的优点,又具有微分模型的优点,因而较为实用和精确。本文应用这一新型微分-积分电弧模型对SF_6喷口电弧的特性进行了计算,并与一些试验进行了对比。     

变直径串联喷嘴内流特性研究

喷嘴在分层注入过程中起到调节聚合物分子量和压力损失的作用,而多级喷嘴的结构,由于分子链的逐级剪切作用,可在保证注入粘度的同时,更大的减小压力的损失.在此基础上提出变直径多级喷嘴的几何结构,利用Fluent数值模拟软件,对单级喷嘴、等直径多级喷嘴进行数值模拟,分析不同结构喷嘴对三元复合溶液速度、压力、湍动能以及平均应变速率的影响,结果表明随着流量的增大,三种结构喷嘴的压力损失和平均应变速率均增大,合理的变直径串联喷嘴可以达到与等直径串联喷嘴相同的注入效果,同时尺寸较小,方便工程应用.     

水煤浆喷嘴热冲蚀磨损机理研究

采用1Crl8Ni9Ti不锈钢、YG8硬质合金和Al2O3／(W，Ti)C陶瓷3种材料制备了水煤浆喷嘴，考察了其在水煤浆雾化和燃烧过程中的热冲蚀磨损机理．结果表明：喷嘴材料的硬度对水煤浆喷嘴的热冲蚀磨损行为具有重要影响；在相同条件下，高硬度的Al2O3／(W，Ti)C陶瓷喷嘴的冲蚀率最低，YG8硬质合金次之，硬度较低的1Crl8Ni9Ti不锈钢喷嘴的冲蚀率最高；在热冲蚀磨损工况下，1Crl8Ni9Ti不锈钢水煤浆喷嘴主要呈现微切削特征，YG8硬质合金水煤浆喷嘴主要呈现晶粒剥落特征，而Al2O3／(W，Ti)C陶瓷水煤浆喷嘴主要呈现研磨损伤和热崩特征．     

含水乙醇多孔直喷喷油器喷雾特性试验研究

含水乙醇在具有现有燃料乙醇优点的同时,还可以降低生产过程中的能源消耗和排放。应用高速摄像机和定容弹系统,在五孔直喷汽油喷油器上研究体积分数95%的含水乙醇在不同燃油温度和喷射背压下的喷雾特性,分析其喷雾形态、贯穿距、喷雾锥角、喷雾宽度、喷雾投影面积及闪沸现象,并与纯汽油的喷雾特性进行对比。研究结果表明：含水乙醇喷雾处于冷态射流状态时,贯穿距大于汽油并随背压升高而降低、油温升高而升高;喷雾锥角小于汽油,并随着背压升高而减小;在完全闪沸状态下,喷雾坍塌成单束油束,喷雾贯穿距明显增长,喷雾锥角明显减小,在靠近喷孔区域喷雾宽度增加,远离喷孔区域喷雾宽度减小,此时喷雾投影面积主要受喷射背压影响。     

Numerical study of hysteresis in annular swirling jets with a stepped‐conical nozzle

This study investigates the experimentally observed hysteresis in the mean flow field of an annular swirling jet with a stepped‐conical nozzle. The flow is simulated using the Reynolds‐averaged Navier–Stokes (RANS) approach for incompressible flow with a k–ε and a Reynolds stress transport (RSTM) turbulence model. Four different flow structures are observed depending on the swirl number: ‘closed jet flow’, ‘open jet flow low swirl’, ‘open jet flow high swirl’ and ‘coanda jet flow’. These flow patterns change with varying swirl number and hysteresis at low and intermediate swirl numbers is revealed when increasing and subsequently decreasing the swirl. The influence of the inlet velocity profile on the transitional swirl numbers is investigated. When comparing computational fluid dynamics with experiments, the results show that both turbulence models predict the four different flow structures and the associated hysteresis and multiple solutions at low and intermediate swirl numbers. Therefore, a good agreement exists between experiments and numerics. Copyright © 2006 John Wiley & Sons, Ltd.