惯性约束聚变靶丸内杂质气体抽空流洗过程的数值模拟

低温冷冻靶是实现惯性约束聚变(inertial confinement fusion,ICF)的关键部件之一.低温靶靶丸内杂质气体的去除程度和效率对低温靶燃料冰层的在线制备具有重要意义.依据低温靶物理对冰层杂质含量的设计要求,在计算靶丸内杂质气体最大允许分压的基础上,建立了靶丸内气体在微米级充气管内流动的抽空流洗模型.模拟研究了不同微管尺度及结构、温度对靶丸内杂质气体抽空流洗效率的影响规律,获得了靶丸充气微管的最佳管型设计方案.基于最佳管型设计,优化得到了具有最高抽空流洗效率的抽空时间与流洗次数组合策略.     

一种标准对涡旋流畸变发生器的优化设计

为研究对涡旋流对压气机性能和稳定性的影响,基于一种叶片式旋流畸变发生器进行优化设计,利用数值模拟方法研究了不同几何参数对畸变发生器模拟精度的影响。结果表明:采用叶片稠度为1.45的CDA叶型时,后掠布局的畸变发生器所产生流场的复现有效性最高,总压损失最小。优化后的畸变发生器相较于已有畸变发生器,总压恢复系数提升了 2.2%,在设置的三个测环上,旋流角误差分别减小了 18.2%,48.45%,0.3%。     

跨音压气机基于前掠和小翼联合扩稳方法研究

针对NASA的Rotor37转子,采用数值方法详细研究了气动前掠和压力面叶尖小翼两种控制方法对其总体性能和叶尖流场结构的影响机制。数值结果表明,单独采用前掠和同时采用前掠和小翼联合作用分别使压气机稳定工作范围提升20.1%和27.7%,且对压气机的效率和增压比影响较小。气动前掠一定程度上抑制了间隙区泄漏流引发的气动损失及低速区范围,但是会导致尖区边界层分离及损失明显增加。相比之下,压力面叶尖小翼对由泄漏流诱发的低速区和吸力面边界层分离区均有较好的抑制效果,从而实现压气机稳定工作范围的明显提升。此外,气动前掠和叶尖小翼的作用效果也表明,转子叶顶的静压差虽然是间隙泄漏流的直接驱动力,但不是影响泄漏流强度和作用范围的唯一因素。     

汽轮机静叶栅内平行通道除湿特性研究

火电汽轮机低压级组和核电汽轮机/船用核动力汽轮机全级都处于湿蒸汽区,湿蒸汽凝结流动长期以来是影响汽轮机经济性和安全性的难题.针对White叶栅,在吸力面和压力面间设计了一个连接相邻的汽流通道的平行通道,采用双流体模型对原型叶栅和改型叶栅内湿蒸汽凝结特性和气动性能进行研究.以总压损失系数、湿汽损失为评价指标,研究了平行通道开设位置对叶栅性能的影响.研究表明:吸力面开设位置(D点)越靠近叶栅尾缘,改型叶栅除湿性能越好;压力面开设位置(C点)对改型叶栅除湿性能影响不大;C点和D点越靠近叶栅尾缘,总压损失系数越大.     

严重段塞流立管压差信号的周期特性分析

本文对集输-立管系统中低气液流速下的气液两相流动特性进行了研究,结合概率密度函数(PDF)和功率谱密度分布(PSD)方法获得了气液流速对严重段塞流周期特性的影响规律.其中第一类严重段塞流立管压差信号的PDF与PSD分布均呈明显的单峰结构,PDF峰值为液塞流出时间在整个段塞周期内的占比,PSD主峰频率的倒数为压差波动信号的周期.分析发现表观液速一定,表观气速的增加会导致整个段塞周期与液塞流出时间占比的迅速减小;而表观气速不变表观液速的增加只会减小段塞周期,不会对液塞流出时间的占比产生较大影响.     

多化学组份反应气体流动的Godunov格式

本文将单介质气体流动的Goduoov方法推广到多化学组份气体流动的计算中,建立了多化学组份气体的间断分解公式以及任意四边形网格下的Godunov方法的差分格式,提出了处理自由边界的虚相法,应用第二类网格,计算了超音速射流及其冲击问题的几个算例,并且同实验结果进行了比较。     

点、线接触真实粗糙表面的弹流润滑研究

本文给出了点、线接触的真实粗糙表面的微弹流数值解。在给定随机粗糙表面样本后,求解大小不同的载荷和粗糙的弹流问题。从计算结果可以看出,由于Reynolds方程中速度项的作用,在表面对应粗糙的位置处引起了压力变化,从而因其产生的弹性变形使粗糙变得平滑。对此光滑表面解可以看出,因粗糙引起的压力和膜厚的变化在光滑解附近波动。载荷较大时,压力分节接近固体接触情况。     

考虑法向压力梯度的三维旋转边界层计算

本文以量级分析为基础,建立了一般曲线坐标系上的三维旋转边界层方程。对旋转在边界层中的影响进行分析之后,提出了一个能够处理壁面法向压力梯度不为零问题的压力梯度迭代方法。在传统的Box法的基础上发展了一套完整的求解三维旋转边界层的方法和程序,并对螺旋面、压气机转子叶面以及圆柱面上的旋转边界层进行了计算,与他人的计算和实验的对比分析表明,该方法和程序是正确的,可用于求解任意几何物面上的三维旋转边界层。     

DUAL CHARACTERS OF INTERACTION BETWEEN PARTICLES AND FLUID

The unique characteristics of gas-solids two-phase flow and fluidization in terms of the flow structures and the apparent behavior of particles and fluid-particle interactions are closely linked to physical properties of the particles, operating conditions and bed configurations. Fluidized beds behave quite differently when solid properties, gas velocities or vessel geometries are vaded. An understanding of hydrodynamic changes and how they, in turn, influence the transfer and reaction characteristics of chemical and thermal operations by variations in gas-solid contact, residence time, solid circulation and mixing and gas distribution is very important for the proper design and scale-up of fluidized bed reactors. In this paper, rather than attempting a comprehensive survey, we concentrate on examining some important positive and negative impacts of particle sizes, bubbles, clusters and column walls on the physical and chemical aspects of chemical reactor performance from the engineering application point of view with the aim of forming an adequate concept for guiding the design of multiphase fluidized bed chemical reactors.     

RESEARCH ON METHOD TO CALCULATE VELOCITIES OF SOLID PHASE AND LIQUID PHASE IN DEBRIS FLOW

Velocities of solid phase and liquid phase in debris flow are one key problem to research on impact and abrasion mechanism of banks and control structures under action of debris flow. Debris flow was simplified as two-phase liquid composed of solid phase with the same diameter particles and liquid phase with the same mechanical features. Assume debris flow was one-dimension two-phase liquid moving to one direction, then general equations of velocities of solid phase and liquid phase were founded in two-phase theory. Methods to calculate average pressures, volume forces and surface forces of debris flow control volume were established. Specially, surface forces were ascertained using Bingham's rheology equation of liquid phase and Bagnold's testing results about interaction between particles of solid phase. Proportional coefficient of velocities between liquid phase and solid phase was put forward, meanwhile, divergent coefficient between theoretical velocity and real velocity of solid phase was provided too. To state succinctly before, method to calculate velocities of solid phase and liquid phase was obtained through solution to general equations. The method is suitable for both viscous debris flow and thin debris flow. Additionally, velocities every phase can be identified through analyzing deposits in-situ after occurring of debris flow. It is obvious from engineering case the result in the method is consistent to that in real-time field observation.