400W行波热声发电系统的实验研究

本文阐述了为太阳能发电系统设计的400 W行波热声发电系统(TWTAEG)的实验研究过程.实验系统由行波热声发动机和直线发电机组成,系统采用平均压力为3.5 MPa的氦-氩混合气体为工质,其中氩气分压比为1.4%,系统运行频率为74Hz.实验中最大输出电功为446 W,此时的热电效率为13%;在输出电功为416 W时热...     

激光脉冲参数对冲击点火的影响

针对激光脉冲参数对冲击点火的影响进行理论分析和数值模拟.首先从冲击波的产生和碰撞过程出发,理论分析冲击脉冲峰值功率、脉宽和上升沿时间对点火的影响;然后通过数值模拟,以点火时间窗口作为评价标准,验证理论分析结果.研究表明:冲击脉冲峰值功率是点火成败的关键因素之一,脉冲宽度则需达到百皮秒以提供足够的点火能量,上升沿时间在小于600 ps的情况下不会对点火造成明显影响. 关键词： 冲击点火 激光冲击脉冲 点火时间窗口     

变循环发动机模型的求解算法研究

采用部件法建立了变循环发动机的多维非线性隐式方程组模型,模型具有隐式性,因而求解过程复杂,收敛困难.针对上述问题,采用遗传算法和牛顿-拉夫逊法进行模型求解,提出了算法的有效性评价指标:初值敏感性、收敛性和稳定性.对两种算法进行有效性评价.针对发动机工作性能最优化问题,建立了多目标模型,用遗传算法进行求解,并分析了相关变量随马赫数变化的规律.结果可为变循环发动机模型求解算法的选择与设计提供参考.     

Simulation of quasi-dimensional combustion model for predicting diesel engine performance

In order to improve the precision of quasi-dimensional combustion model for predicting diesel engine performance and promote the real time operating performance of the simulation model, a new phase-divided spray mixing model is proposed and the quasi-dimensional combustion model of diesel engine working process is developed. The software MATLAB/Simulink is utilized to build the quasi-dimensional combustion model of diesel engine working process, and the performance for diesel engine is simulated. The simulation results agree with experimental data quite well. The comparisons between them show that the relative error of power and brake specific fuel consumption is less than 2.8% and the relative error of nitric oxide and soot emissions is less than 9.1%. By utilization of this simulation model with personal computer, the average computational time for one diesel engine working process is 36 s, which presents good real time operating performance of the model. At the same time, the influence of parameters in calculation of air entrainment on prediction precision of diesel engine’s simulation model is analyzed.     

线性唯象传热定律下光驱动发动机的最优路径

以存在热漏、摩擦等不可逆性,以双分子反应系统2SO3FS2O6F2为工质的光驱动发动机为研究对象,考虑工质与环境之间传热服从线性唯象传热定律[q∝Δ(T-1)],分别以输出功最大和熵产生最小为目标对整个循环活塞运动的最优路径进行研究.利用最优控制理论得出了活塞运动路径及工质温度的最优构型,给出了最优构型的数值算例,并与牛顿传热定律[q∝Δ(T)]下的最优构型进行了比较.     

The spontaneous formation of inhomogeneity in a classical one-particle “gas”: An example in silico

A single classical isoergic particle was placed in a cube and allowed to propagate for 100 ns to 10 ms. The interaction of the particle with the inner wall of the cube was modeled as a linear combination of specular and random reflection, the extent of the combination being governed by a user-defined “roughness” parameter α. As a function of α, the particle’s relative pressure and density spontaneously took on an inhomogenous distribution.     

一种富于启发性的热机实验演示与分析

利用试管、玻璃球、器、圆盘等易取材料研制了使玻璃球通过重力作用原理来转移工作物质的方法，并可用燃烧热、电阻热和光转化热作为高温热源的动力的热机实验演示，同时我们给出了相应的理论分析。     

基于火花放电等离子体部分氧化重整二甲醚制氢研究

应用自制的多级式等离子体富氢气体制备装置，进行了二甲醚部分氧化重整制氢实验。实验结果表明，常温常压下二甲醚的转化率和氢产率随占空比的增大先增大后减小，当占空比为80%时最大值分别为87.6%和39.4%。随着电源电压的增加，放电能量和持续时间逐渐增加，转化率和氢产率逐渐增加。当反应器采用保温措施或对反应物进行加湿时，转化率和氢产率均有明显提高，同时制氢能耗下降，热效率有一定提高。实验过程中附着在电极上的积炭主要是由于氧气不足造成，随空醚比的增大，积炭明显减少。     

Size-dependent ignition temperature of metallic compounds fabricated by self-propagating high-temperature synthesis

Considering the diffusion reaction at solid interfaces, the ignition temperature of compounds fabricated by self-propagating high-temperature synthesis (SHS) is modelled with the help of size-dependent activation energy. As reactant size decreases, ignition temperature also decreases. This is because of increased contact areas between the reactants and the lowered diffusion barrier, both of which must be calculated specifically for reactants in nanoscale. The model predictions and experimental results are consistent for some metallic compounds.