基于支持向量回归的腔体滤波器机电耦合建模与优化

为了提高装配后的滤波器电性能和成品率,该文提出了一种基于支持向量回归的腔体滤波器机电耦合建模和优化方法。该方法根据工程中积累的经验数据,首先应用改进的多核线性规划支持向量回归算法建立了制造精度对滤波器电性能影响的机电耦合模型,然后应用此模型优化了滤波器的制造精度,从而获得了最优的机械结构尺寸。实际滤波器的实验结果验证了该方法的有效性。该方法可用于批量生产的腔体滤波器的计算机辅助制造系统中。     

Radiative properties of a solar cavity receiver/reactor with quartz window

An energy transfer and conversion model for high-temperature solar cavity receivers has been developed using the transport behaviour of solar radiation as described by the spectral radiative exchange factors. A Monte-Carlo ray-tracing method coupled with optical properties was adopted, to predict radiation characteristics of the solar collector system by calculating radiative exchange factors. A cavity receiver with a plano-convexo quartz window was proposed, based upon the directional characteristics of the focal flux and the redistribution effect of the quartz window. Parametric studies on the windowed receiver provided a more uniform flux distribution, higher efficiency and lower loss than the windowless receivers. The predicted results serve as a design reference for the solar receivers or reactors in high-temperature applications.     

100 t顶吹转炉三维可压缩流场的数值模拟

通过利用Fluent流体软件及标准κ-ε方程模型,研究氧气压力(11.46×10⁵Pa和6.88×10⁵ Pa)及氧枪位置(1.2~1.5 m)对钢厂100 t顶吹转炉氧枪射流特性及钢液表面冲击的影响。结果表明,随氧气压力的增大,氧气在转炉内高速区范围变大,射流核心段长度变长,且气流的压能增加;氧气压力为11.46×10⁵Pa时,当枪位由1.2 m提到1.5 m时,钢液表面氧气流最大冲击速度由240 m/s降低至194 m/s,高速区面积减少,钢液凹坑深度由0.37~0.43 m降至0.30~0.36 m,同时凹坑最大直径由0.70~0.80 m增至0.80~0.95 m。     

矿用三维激光扫描测量系统的研制

研制出具有自主知识产权的矿用三维激光扫描测量系统。分析了激光测距的工作原理,设计了系统结构与镜头防护方法;研究了系统综合通讯方法,开发了系统控制软件,实现了运动控制、数据通讯、上位机显示、三维重建等功能。现场试验表明,系统可准确测量空区三维形态,计算空区相关参数,为采空区安全评价与综合治理提供可靠技术手段。     

Characteristics of the hydrogen jet combustion through multiport injector arrays in a scramjet combustor

Large eddy simulation of the hydrogen jet combustion in a cavity-stabilized scramjet combustor with three parallel injectors is performed in this study, the emphasis of which is placed on the turbulent flame regime as well as the overall performance analysis. This combustor operates in a scramjet mode with a global equivalence ratio of 0.124, as the chemical heat released is not enough to form thermal chocking. The code framework utilizes an adaptive central-upwind weighted essentially non-oscillatory scheme with a low numerical dissipation to accurately capture turbulent structures in the flowfields, and an assumed probability density function approach to close the terms of the production rate of species. Turbulent fluctuations in the incoming boundary layer are initiated and sustained by a multi-wall recycling/rescaling technique, augmenting the mixing degree of the jet and crossflow. The numerical results show that the large scale vortices between the adjacent jet wakes interfere with each other in the downstream, resulting in a portion of the premixed flame. However, the turbulent diffusion combustion still dominates the whole combustor, occurring in a widespread range of Mach number. And the violent chemical reaction favours a high-temperature environment with a proper scalar dissipation rate. The diameter of multiple jets is smaller in comparison to that of the single injection, so that its penetration height is a little lower under the same spout pressure. Altogether, the parallel injection strategy is beneficial to improve the overall combustor performance, and will not lead to excessive total pressure loss.     

腔体内壁脊形凹槽对微波反应器加热效率及均匀性的影响

提出在微波反应器腔体内壁设置脊形凹槽的优化策略,研究在保证加热效率的前提下提升微波加热的均匀性。利用有限元法仿真研究不同凹槽结构参数对微波反应器加热效率和均匀性的影响。研究结果表明:脊型凹槽结构能有效提升微波反应器的加热效率和加热均匀性。优化后微波反应器的加热效率达到98.75%,与微波腔壁光滑时相比,均匀性最大提升幅度达到58.54%。     

Large-Eddy/Reynolds-averaged Navier–Stokes simulation of combustion oscillations in a cavity-based supersonic combustor

Combustion oscillations in a supersonic combustor with hydrogen injection upstream of a cavity flameholder are investigated numerically using a hybrid RANS/LES (Reynolds-Averaged Navier–Stokes/Large-Eddy Simulation) method acting as a wall-modeled LES. A turbulent boundary layer with thickness of δ_inf = 2.5 mm is considered and a recycling/rescaling method is adopted to treat the unsteady inflow. The results show that combustion oscillations can mainly be attributed to two mechanisms. One is the unsteady flame spreading from the cavity shear layer to the main stream, which is greatly influenced by the interaction of the jet-with-cavity shear layer. This mechanism leads to relatively low-frequency oscillations that correspond to the cavity-shear layer oscillations. The other is the auto-ignition of the combustible fluid packets formed around the fuel jet accompanied by the generation of the hairpin-like vortices, which leads to relatively high-frequency oscillations that correspond to the jet instabilities.     

CH4/CO2 reforming over La2NiO4 and 10%NiO/CeO2–La2O3 catalysts under the condition of supersonic jet expansion via cavity ring-down spectroscopic analysis

CH₄/CO₂ reforming over La₂NiO₄ and 10%NiO/CeO₂–La₂O₃ catalysts under the condition of supersonic jet expansion was studied via direct monitoring of the reactants and products using the sensitive technique of cavity ring-down spectroscopy. Vibration–rotational absorption lines of CH₄, H₂O, CO₂ and CO molecules were recorded in the near infrared spectral region. Our results indicated that La₂NiO₄ is superior to 10%NiO/CeO₂–La₂O₃ in performance. In addition, we observed enhanced reverse-water-gas-shift reaction at augmented reaction temperature. The formation of reaction intermediates was also investigated by means of time-of-flight mass spectrometry and there was the detection of CH_x⁺, OH⁺ and H⁺ species.     

精密塑料齿轮收缩率对模具型腔尺寸设计的影响

利用Moldflow软件Flow-Shrink模块,研究了精密塑料齿轮不同位置的收缩率,得到指导塑料齿轮模具型腔设计依据。     

基于CAE的保鲜盒注塑成型模拟与分析

在Pro/Engineer软件中建立制品模型,运用Moldflow软件分析保鲜盒盖与盒体的最佳浇口位置,在保鲜盒盖与盒体组合型腔进行流道平衡分析基础上,进行填充、冷却等过程的模拟。