可调轴向叶片结构旋流强度计算与动力场特性分析

旋转射流对燃烧器的燃烧过程起着重要的作用,可调轴向叶片旋流器是实现旋转射流的重要途径。为了充分发挥可调轴向叶片旋流器的结构简单、阻力损失小、出口速度分布均匀以及调节性较好等优势,基于可调轴向叶片旋流器的工作原理,研究不同旋流强度下燃烧室内轴向速度、切向速度、径向速度的径向分布以及煤粉火焰温度的轴向与径向分布,对系统改变旋流器位置后可调轴向叶片旋流器的动力场特性进行分析,确定旋流器的结构参数并推导可调轴向叶片旋流器旋流强度的计算公式。研究结果表明:调节旋流器位置可改变气流轴向动能和切向动能的大小,导致旋流器出口附近轴线逆压梯度区的建立,使得气流反转以影响流场;随着旋流强度的增大,中心回流区面积增加,烟气温度峰值首先出现在燃烧器喷口附近,整个回流区内平均温度较高且比较均一,说明提高旋流强度有助于燃烧器内煤粉的稳定着火。

车辆动态特性场的研究

在车辆的运行过程中，较多时间处于加速或减速等动态工况。研究车辆的动态特性场，可以更加全面地了解和利用车辆的性能。本文提出了车辆动态特性场的概念并论述其生成方法，在实际测试的基础上，确定了某车的动态动力特性场。

切圆燃烧锅炉深度调峰工况下燃烧器出口风速变化特性分析

为有效改善炉膛内的空气动力场特性,对某300 MW锅炉设备及运行参数进行理论计算分析,研究了四角切圆燃烧锅炉在设计工况与深度调峰工况下燃烧器出口一次风速、二次风速、二次风与一次风动量比的变化特性。结果表明深度调峰工况下的燃烧器出口一次风速与热耗率验收(turbine heat acceptance,THA)工况设计值相比仅小幅下降,而燃烧器出口二次风速却出现了大幅下降,从而使得二次风与一次风的动量比显著降低,二次风对炉膛空气动力场的组织能力显著下降。根据计算结果可知,随着锅炉负荷的下降,未投运燃烧器层数越多,对炉膛空气动力场的影响越小;未投运燃烧器层冷却风量越大,对炉膛空气动力场的影响越大。

Characteristic and Mechanism of Pressure Fluctuation Caused by Self-Induced Oscillation of Supersonic Impinging Jet

When the underexpanded supersonic jet impinges on the obstacle, it is well known that the self-induced flow os- cillation occurs. This oscillation depends on the pressure ratio in the flowfield, the position of an obstacle and is related with the noise problems of aeronautical and other industrial engineering. The characteristic and the mechanism of self-induced flow oscillation, have to be clarified to control various noise problems. But, it seems that the characteristics of the oscillated flowfield and the mechanism of an oscillation have to be more cleared to control the oscillation. This paper aims to clarify the effect of the pressure ratio and the obstacle position and the mechanism of self-induced flow oscillation by numerical analysis and experiment, when the underexpanded su- personic jet impinges on the cylindrical body. From the result of this study, it is clear that occurrence of the self-induced flow osciUation depends on the pressure balance in the flowfield.