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《等离子体科学和技术》2015,17(1):10-13
For achieving the scientific mission of long pulse and high performance operation,experimental advanced superconducting tokamak(EAST) applies fully superconducting magnet technology and is equiped with high power auxiliary heating system.Besides RF(Radio Frequency) wave heating,neutral beam injection(NBI) is an effective heating and current drive method in fusion research.NBCD(Neutral Beam Current Drive) as a viable non-inductive current drive source plays an important role in quasi-steady state operating scenario for tokamak.The non-inductive current driven scenario in EAST only by NBI is predicted using the TSC/NUBEAM code.At the condition of low plasma current and moderate plasma density,neutral beam injection heats the plasma effectively and NBCD plus bootstrap current accounts for a large proportion among the total plasma current for the flattop time. 相似文献
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In the linear transformer driver (LTD) technology, the low inductance energy storage components and switches are directly incorporated into the individual cavities (named stages) to generate a fast output voltage pulse, which is added along a vacuum coaxial line like in an inductive voltage adder. To provide the theoretical foundation for structure design and ensure the reliable operation of the planar multi-gap multi-channel gas switches, numerical simulation of voltage applied to the gaps is carried out, taken into account a variety of factors such as working coefficient, triggering voltage, resistance of crosswise resistors, and coupling capacitance. Based on the theoretical analysis of development and maintenance of parallel discharge channels, simulation of voltage applied to the gaps was performed in PSpice program. The results of simulation show that high working coefficient, high triggering voltage, high resistance of crosswise resistors and high coupling capacitance are all beneficial to the increase of the voltage applied to the gaps. 相似文献
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In order to realize steady-state operation of the neutral beam injection(NBI) system with high beam energy,an accurate thermal analysis and a prediction about working conditions of heat-removal structures inside high-heat-flux(HHF) components in the system are key issues.In this paper,taking the HHF ion dump with swirl tubes in NBI system as an example,an accurate thermal dynamic simulation method based on computational fluid dynamics(CFD) and the finite volume method is presented to predict performance of the HHF component.In this simulation method,the Eulerian multiphase method together with some empirical corrections about the inter-phase transfer model and the wall heat flux partitioning model are considered to describe the subcooled boiling.The reliability of the proposed method is validated by an experimental example with subcooled boiling inside swirl tube.The proposed method provides an important tool for the refined thermal and flow dynamic analysis of HHF components,and can be extended to study the thermal design of other complex HHF engineering structures in a straightforward way.The simulation results also verify that the swirl tube is a promising heat removing structure for the HHF components of the NBI system. 相似文献
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《核动力工程》2015,(6):61-66
在对低速气体进行计算流体力学(CFD)数值模拟时,通常忽略气体的可压缩性。当计算体系中存在较大温差和较大组分浓度差时,不可压缩近似会因带来很大计算误差而失效。针对此问题,低马赫数方法通过将实际压力拆分为热力学压力和动力学压力的方式,将物性参数与热力学压力联系起来,在对不可压缩流动求解器进行较小改造后,较准确地处理低马赫数下的可压缩流问题。利用Code_Saturne程序实现该模型,并针对空气射流破坏轻密度气体分层现象进行模拟。首先通过网格敏感性分析,选定中等密度网格为计算网格;然后在比较不同算法的模拟结果中发现,采用低马赫数方法可以明显提高计算精度。最后,利用模拟结果,对空气射流破坏氦气分层实验中氦气的水平分布情况进行分析和讨论。 相似文献
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针对反应堆主管道45°安注斜接管嘴,基于1:9的比例模型,采用计算流体力学程序(CFX)软件,进行了常压条件下安注斜接管嘴主、射流温差分别为30℃和70℃、射流和主流的流速比为0.87~40、构件不同区域内非等温横向射流时的壁温变化及其分布特征的数值模拟研究,得出了构件内主接管相交区、射流下游区、主管侧面区及主管底部各区域测点近壁流体的混合函数。通过对射流与主管流体两种温差下各区域测点混合函数的比较发现,在本次研究中,30℃、70℃两种温差下各点混合函数基本保持不变,各点混合函数的大小与温差关系不大。将本文混合函数的计算结果与同期试验结果进行了比较,二者符合良好。 相似文献
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离心机流场非稳态过程的初步数值模拟 总被引:3,自引:0,他引:3
摘要:从非稳态线性离心机流场运动方程出发,利用有限体积法,采用交错网格得到离散方程。通过数值求解得到了存在温度驱动情况下,离心机内形成小扰动流场的过程。从形成小扰动流场的非稳态过程可以看出扰动流场在开始和稳定阶段的影响因素不同,从温度引起的轴向压强的不平衡引起流动逐渐过渡到压强分布不同而引起的轴向环流。数值模拟为更好地研究离心机内流场的非稳态过程提供了依据。 相似文献
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《Journal of Nuclear Science and Technology》2013,50(5):307-316
In order to evaluate the aerosol behavior in detail in the cover gas region of LMFRs, a numerical method was developed by considering the aerosol radius as one of the space coordinates. In this method, the governing equations for the compressible gas were approximated by removing the sound wave in order to efficiently calculate the temperature field with a large gradient. The convection terms of these equations were discretized by the 3rd order upwind scheme which was derived for an irregular spaced staggered mesh system. Although it was shown in a previous study that this method was reasonable by calculating basic heat transfer tests of the cover gas region, it is desirable to improve the method in order to achieve more accurate results. In this study, advanced models were developed which simulate the interaction between the mixed gas and aerosols in the flow field. A comparison of the calculated results vs. the experimental results indicated good agreement of temperature distribution. In addition, the aerosol mass concentration in the cover gas region could be evaluated much better with this advanced model. 相似文献
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窄间隙矩形多通道流动交混特性数值模拟 总被引:1,自引:0,他引:1
采用CFD程序CFX对窄间隙矩形多通道内流体的交混特性进行了数值模拟.数值计算结果表明:流体经过全部的交混段后,两边侧边通道内的流量低,中间4个主通道内的流最高.入口流量大小不同的条件下,流体经过全部的交混段后,主通道内的流量都趋于一致.前4段的流动交混较为明显,随着轴向交混段的增加,交混量越来越小;流体交混时,主通道入口流量大的通道内的流体向入口流量小的通道内运动,初始阶段在侧边通道和交混段产生了较强的二次流,但随着轴向交混段的增加,二次流变得越来越小. 相似文献
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《Journal of Nuclear Science and Technology》2013,50(7):743-751
This paper describes the detail numerical methods for the aerosol behavior in the cover gas regions of LMFRs by considering the aerosol growth as one of the space coordinates. The governing equations for the compressible gas were approximated by removing sound waves for the efficient calculations of the large temperature different fields. The convection terms of these equations were discretized by the 3rd order upwind scheme which was derived for irregular staggered mesh. In order to verify this method, a natural convection in the vertically heated enclosure was calculated and the results were compared with the benchmark results by de Vahl Davis. In this calculation, temperature distribution in the enclosure agreed well with each other. The basic heat transfer tests for the cover gas region of LMFRs were also calculated by this method and the calculated vertical average temperature profile of the turbulent cover gas natural convection and the aerosol average mass concentration were compared to the experimental ones. The calculated temperature agreed well with the experimental ones. It was also estimated that the aerosol were well mixed in the natural convection field and the number densities distributed the similar profiles in almost all region except for the region near the top surface. 相似文献
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杆式支撑换热器换热的数值模拟 总被引:1,自引:0,他引:1
采用数值模拟方法研究杆式支撑换热器.可以克服实验研究方式的不足。利用相似理论确定数值模拟模型,分析了各结构参数变化对换热器传热和流动性能的影响.利用最小二乘法.进一步回归出杆式支撑换热器层流下的传热和流动阻力的准数关联式.设计,建造了一套可变结构参数的杆式支撑换热器热模实验装置.在壳程单排管间布杆或双排管间布杆、不同流速和不同折流栅结构参数情况下测得了100个实验值.将实验测量值和计算值进行了比较。结果表明:数值模拟计算的Nu值和△p值与实验测量值吻合很好,由实验数据回归得到的传热和流动阻力无因次准数关系式与数值模拟程序计算得到的准数关系式也吻合较好.显示出数值模拟方式进行换热器研究的显著优点. 相似文献
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对于气液两相分离,传统分离器或体积过大,或旋流强度低,因此考虑提出一种新式的涡流式分离器。利用涡流二极管逆向流动形成强度较高旋流的特点,在旋流腔上方加入一根支管,从切向入口进入的两相流由于密度差和旋流的作用,气相会聚集在中心由于浮力作用从上支管流出分离器,液相会分布在四周由于重力作用从下支管流出分离器,从而实现两相分离。采用数值模拟的方式分别对不同旋流腔尺寸以及出口形状的分离器进行计算,模拟结果表明,在进口流量为0.5 t/h、入口含气率1%~5%工况下,控制底流口压力和入口相同,溢流口与入口压差在80~90 kPa范围内,分离器对粒径在50~100μm的气泡分离效率可以达到90%以上。 相似文献