X波段磁绝缘线振荡器的模拟研究

设计了一个具有新型收集极的X 波段磁绝缘线振荡器,并利用KARAT程序对其进行了深入的数值模拟研究。对设计思想进行了介绍,并对典型模拟结果进行了图示和分析。当工作电压为520 kV, 电流为64 kA时, 模拟中获得了2.18 GW的微波输出功率,频率为9.3 GHz,功率转换效率为6.5％, 辐射微波的主模式为TEM模。     

采用化学链式燃烧器的固体氧化物燃料电池发电系统优化

化学链式燃烧器和固体氧化物燃料电池相结合的发电系统是一种新型联合循环。本文通过对包含更多可能结构的改进流程进行系统参数和流程同步优化,达到进一步提高循环性能的目的。     

Exit-flow velocity survey of two single-tangential-inlet vaneless turbine volutes

The most cited analytical technique for designing turbine volutes is to assume the throughflow is free from torque, although for this assumption to hold, the volute walls must lie near what would be streamlines in an unbounded free vortex-plus-sink flow. The single tangential inlet design, with inlet offset decreased and diameter increased to attain the weak exit swirl required by high specific speed turbines, deviates from such a shape, and the volute’s internal geometry is no longer torque-free. It is desired to know the actual time-averaged flow leaving such a volute, so that a rotor can be designed to compliment it.For two existing single tangential inlet volutes, time-averaged radial and tangential velocity and static pressure measurements of exit flow have been obtained on a cylindrical cut plane through the radial-inflow section using a three-port yawmeter in air. The Reynolds numbers based on inlet pipe mean conditions, around 10⁵, are well into the fully-turbulent regime and on the order of comparable water turbines.A comprehensive map of time-averaged exit flow of both volutes is presented. The integrated values of gross angular momentum flux change and total pressure loss coefficient are tabulated. Circumferential variation of flowrate and swirl strength highlight unexpected differences in outlet flow between the two volute designs. Results are presented alongside corresponding numerical results from the commercial package Fluent (Fluent, Inc., Lebanon, NH, USA) using Reynolds stress, k-ω, and inviscid flow models.In both volutes, measured gross exit angular momentum flux was more than 1.7 times what the zero-torque assumption would predict when blindly applied to the volute as a whole. This discrepancy is attributed to significant turning near the volute’s inlet region leading to an updated view of what an appropriate control volume is when applying the zero-torque assumption. Additionally, variation of both radial and tangential velocity in both the circumferential and axial directions on the order of 15% of the mean value reveal that volute swirl characterization by a single measurement would have a significant associated uncertainty.     

An experimental investigation of the interaction of swirl flow with partially premixed disk stabilized propane flames

The present work describes the experimental investigation of reacting wakes established through fuel injection and staged premixing with air in an axisymmetric double cavity arrangement, formed along three concentric disks, and stabilized in the downstream vortex region of the afterbody. The burner assembly is operated with a co-flow of swirling air, aerodynamically introduced upstream of the burner exit plane, to allow for the study of the interaction between the resulting partially premixed recirculating afterbody flames with the surrounding swirl. At low swirl the primary afterbody disk stabilizes the partially premixed annular jet in the downstream reacting wake formation region. As swirl increases, a system of two successive vortices emerges along the axis of the developing wake; the primary afterbody vortex is cooperating with an adjacent, swirl induced, central recirculation zone and this combination further promotes turbulent mixing in the hot wake.Complementary measurements of the counterpart isothermal turbulent velocity fields provided important information on the near wake aerodynamics under the interaction of the variable swirl and the double cavity produced annular jet stabilized by the afterbody. Under reacting conditions, measurements of turbulent velocities, temperatures and statistics together with an evaluation of the exhaust emissions were performed using LDV, thin digitally-compensated thermocouples and gas analyzers. A selected number of lean and ultra-lean flames were investigated by regulating the injected fuel and the air supply ratio, while the influence of the variation of the imposed swirl on wake development, flame characteristics and emission performance was documented for constant fuel injections. The differences and similarities between the present partially premixed stabilizer and other types of axisymmetric configurations are also highlighted and discussed.     

大速差射流燃烧室中烟煤与贫煤燃烧的数值模拟

本文基于颗粒相的轨道模型,对大速差射流燃烧室中烟煤粉与贫煤粉的二维流动,混合及燃烧进行了数值模拟,模拟结果从两相耦合的角度,阐明了煤粉颗粒在燃烧室中运动的规律,煤粉与大速差射流诱导的中心气体逆流之间的混合及其对煤粉火焰稳定的影响,指出此种燃烧室中煤粉火焰稳定的回流区燃烧机理,气相流场及回流区的预报结果与实验符合良好。     

燃气轮机燃烧室化学反应器网络模型研究

本文针对CFD燃烧室设计方法在计算时间以及计算的准确度上的不足,发展了一种计算量较小的、能够快速准确地预测燃气轮机燃烧室污染物排放的化学反应器网络模型方法(CRN).该方法首先根据CFD的计算结果对燃烧室进行分区,不同的区域采用不同的化学反应器模型进行模拟,反应器之间的连接关系以及入口参数都根据CFD的结果确定.本文采用这种方法对某个燃烧富氢合成气的重型燃气轮机燃烧室的NO_x排放随燃料加湿量的变化进行了预测,并与现场测量的结果进行了比较.计算结果与现场试验数据吻合得很好,证明这是一种很好的预测燃烧室NO_x排放的方法,与CFD方法相比预测精度有了很大提高,而且在计算时间上小了几个数量级.     

环形燃烧室内气相燃烧及两相流动计算

采用TTM法与型线定点法相结合的方式生成带涡流器环形燃烧室贴体网格,在任意曲线坐标系中对其三维两相反应流场进行数值模拟,采用的紊流、燃烧以及辐射模型分别为:标准k-ε方程,EBU-Arrhenius公式,六通量热辐射模型等。在同位网格系下气相采用SIMPLE算法求解,气液两相流动用PSIC法模拟。通过对两种燃烧室的计算结果与实验值比较表明本计算方法合理,所得的计算结果可为环形燃烧室的优化设计提供指导数据。     

Swirl number and nozzle confinement effects in a flat-vane axial swirler

This paper presents the results of a parametric experimental study of free swirling flow at the exit of a flat-vane axial swirler. A total of 16 data sets were acquired by combining four swirler vane angles (22°, 29°, 50.5°, and 58.3°) and four exit nozzles of different diameters (30, 40, 52, and 76 mm). Sophisticated pressure probes consisting of precise microphones and a two-component LDV system were used to investigate the effect of these geometrical parameters on swirling flow regimes characterized by the swirl number. Particular attention was paid to the precessing vortex core (PVC) phenomenon observed at the exit of the swirler nozzle. It has been shown that by varying the vane angle and the diameter of the exit nozzle, it is possible to independently control the swirl number value and the occurrence of a PVC. A distinct correlation has been found between the PVC-induced pressure pulsations detected by acoustic probes and the tangential velocity fluctuations measured by LDV. The use of microphones provides a quick way to measure the frequency response of swirl flow in a wide range of geometries and flow configurations. The PVC effect does not occur at low subcritical values of the integral swirl number (S < 0.5) and in the case of strong swirl flow (S_g = 0.9 and 1.2) in the absence of constriction by the nozzle (D_e/D₀ = 1). The disappearance of the PVC effect for strong swirl flow without constriction is due to the extreme displacement of the flow to the nozzle walls. The absence of a PVC in the flow was inferred not only from measurements of the frequency response of the flow over a wide range of Re numbers, but also from the absence of specific markers in velocity RMS distributions. Measurement results are used to derive an empirical correlation of the integral swirl number and the Strouhal number with a modified geometric swirl number. This allows a generalization of the frequency characteristics of swirling flows with a PVC for flat-vane axial swirlers, which are widely used in engineering.     

短生命周期产品供应链清仓收入共享契约研究

基于快速反应策略的适时清仓,是提高短生命周期产品供应链运营效率及加速产品更新的有效方法。考虑由一个零售商和多个配件供应商组成的两级短生命周期产品组装供应链系统,当市场需求随机变化时,建立了基于清仓收益共享的决策模型,从集中和分散控制两个角度,比较分析了有清仓收入共享和不考虑清仓收入共享下,供应链的总产量和利润的变化。理论推导和数值解分析表明,在考虑清仓收入共享下,供应链的市场供给量增加;而且,在清仓收入共享契约下,供应链利润依据成员成本比重及所分担风险率而得到合理分配,进而提升了供应链的整体协作效益。     

发动机燃烧室数值计算

1引言为了研制或改进发动机燃烧室的设计；了解燃烧室内各气流参数分布对燃烧过程的影响是很有必要的。本文采用数值计算方法模拟涡喷发动机燃烧室内流场和壁温。本文计算的是发动机燃烧室火焰筒流场，所计算的实际几何形状较为复杂，如图1所示，入口处有倾斜壁面，在轴线方向有6排径向孔和6排轴向气膜隙缝槽；火焰筒进口处旋流器叶片安装角为74”，在旋流器内装有一个喷雾角为95”的喷咀。在计算过程中，由于径向小孔不对称，所以计算园周方向为360”园形截面。考虑到火焰筒实际形状，在计算时分前后二段；前段是联管火焰筒部分按三维两相…