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超导同步调相机是一种用于电力系统的新型动态无功补偿设备, 具有高效、 快速响应等优点. 本文描述了10 Mvar 高温超导同步调相机的总体结构, 励磁绕组采用 YBCO 高温超导带材绕制而成, 通过循环的20 K 冷氦气进行冷却. 低温系统主要包含3 台制冷机、1 台氦气泵、 冷头换热器及其他辅助设备, 通过旋转密封装置与电机转子部分进行连接. 本文重点介绍了低温系统的设计方法, 包括转子、 绝热力矩管和电流引线等关键部位漏热和氦气管路流阻的计算方法, 并通过多次降温试验进行实验验证. 通过对带负载试验结果分析得出: 存在最优的氦气压力和氦气泵转速运行参数, 使得电机转子部分获的最佳冷却效果. 通过与300 kvar 高温超导同步调相机的耦合测试发现, 所研制的低温系统可将转子系统冷却至22.4 K, 满足调相机应用中对低温环境的要求. 相似文献
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混合型高温超导发电机采用高温超导带材作励磁材料,结构上与传统电机有较大的不同,设计方法也不尽相同.本文基于傅里叶变换将超导发电机的励磁集中绕组等效为沿转子圆周正弦分布的激励源,建立了超导发电机磁场分析模型.对电机气隙磁场分布进行了求解,并分析了不同绕组张角时气隙磁密波形中的谐波含量.通过参数化分析,研究了不同环境屏、转子的尺寸对电机功率密度的影响.采用有限元法对磁场求解结果进行了验证,结果一致性较好.研究结果表明,励磁绕组张角会对电机气隙磁密波形产生影响,合理设置超导发电机环境屏及转子结构,可以提高超导发动机的功率密度. 相似文献
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Air movement in workplaces, whether resulting from a forced ventilation system or natural airflow, has a significant impact on occupational health. In a huge building of shipbuilding factory, typical harmful factors such as fume or vaporized gas from welding and cutting of steel plates give an unpleasant feeling. From field data survey, the yearly dominant wind directions around the factory building tested were north-west, north-east and south-east. Among the three wind directions, the ventilation improvement was the worst for the north-eastern wind. This study was focused on modification of opening vents in order to utilize the natural ventilation flow effectively. Instantaneous velocity fields inside the 1/1000 scale-down factory building model were measured using a 2-frame cross-correlation PIV method. The factory model was embedded in an atmospheric boundary layer simulated in a wind tunnel. The modified vents improved the internal ventilation flow with increasing the flow speed more than two times, compared with that of present vents. 相似文献
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In this study, a hybrid approach based on computational fluid dynamics (CFD) was used to investigate the aerodynamic forces associated with vortex-induced vibration (VIV) in a circular cylinder. The circular cylinder and the flow field were considered as two substructures of a system. Circular cylinder motion was produced in a wind tunnel test of the VIV prior to the numerical simulation; this motion was used as a known cylinder boundary condition and applied to the flow field. The flow field with the known moving boundary condition was then numerically simulated by the ANSYS CFX code. The transient aerodynamic coefficients of the circular cylinder with predetermined motion were obtained from the numerical simulation. To verify the feasibility and accuracy of the proposed hybrid approach and to calculate cylinder vibrations, the transient aerodynamic coefficients were applied to a single degree of freedom (SDOF) model of the circular cylinder. The oscillation responses of the circular cylinder from the calculated (SDOF model) and experimental results were compared, and the results indicate that the hybrid approach accurately simulated the transient aerodynamic coefficients of the circular cylinder. For further comparison, a nonlinear aerodynamic coefficient model based on a nonlinear least square technique was applied to the SDOF model. The nonlinear aerodynamic model can predict well the amplitude and lock-in region of the VIV of the circular cylinder model. 相似文献
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A carbon black reactor is simulated by means of computational fluid dynamics (CFD). The computed flow and chemical species fields are input for a simulation of particle inception, growth and aggregation. For this complex system quantitative results are still prone to errors. Yet the method is robust enough so that the computed particle field can help understand and explain different aspects of the reactor and the aggregate particles produced. With this knowledge the process designer has a powerful tool for designing new and optimizing existing reactors, in order to obtain truly tailor-made products. 相似文献
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发动机热喷流红外辐射计算与仿真 总被引:1,自引:0,他引:1
利用求每个小视场视线方向辐射亮度的方法计算喷流红外辐射的光谱分布。以辐射传递方程数值和形式为基础,采用Malkmus统计窄谱带模型和Curtis-Godson(CG)近似求视线方向的辐射强度。采用CFD分析软件FLUENT模拟流场和组分摩尔分数分布。建立喷流红外成像仿真模型,仿真生成了液体火箭发动机热喷流红外图像。结果表明,该方法可以很好地分辨出流场的细微结构。该模型也适用于航空发动机喷流红外辐射计算与仿真。 相似文献
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在开源的CFD工具包OpenFOAM环境下开发了基于低磁雷诺数的磁流体湍流数值模拟求解器,对2π×1×1的方管中无磁场湍流和磁流体湍流进行直接数值模拟研究,给出了截面瞬时速度、平均速度的分布,截面对称中心线上的脉动速度的均方根值、湍动能的分布。计算结果表明,外加磁场对磁流体湍流具有抑制作用和并且这种抑制作用具有各向异性。 相似文献
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A number of investigators have tried to develop a generalized prediction method for flow-generated noise produced by in-duct elements in a ventilation system. Most of these prediction methods relied on limited data obtained from conventional measurement techniques that require the use of an expensive and specially combined acoustic and aerodynamic experimental facility. An alternative to using a specialised and aerodynamic facility that is currently gaining favour in building engineering is using computational fluid dynamics (CFD) software packages. CFD is a powerful design tool that is able to predict the behaviour of fluid flow regimes. With the aid of CFD, Mak and Oldham have developed a predictive technique that is based on the relationship between the acoustic power radiated, due to the interaction of air flow and a spoiler, and the turbulent kinetic energy generated in the region of the spoiler. Based on the results of CFD simulation of relevant configurations, the technique has been adopted to normalize the published experimental data of Nelson and Morfey, who produced a normalized spectrum for predicting the sound power level of flow-noise produced by the strip spoilers in a rectangular air duct. In this paper, the theoretical basis of this technique was reviewed and revised. A collapse of data from the simulation models were obtained against the experimental data of Oldham and Ukpoho. The data collapse for a damper were generally excellent at most Strouhal numbers. The data collapse for an orifice plate were generally excellent at lower Strouhal numbers but was less efficient at higher Strouhal numbers where considerable scatter was observed. 相似文献