熔盐堆流体动力学模型降阶方法适用性分析  

Applicability analysis of reduced order modeling methods for fluid dynamics in molten salt reactor

作　　者：林铭 程懋松[1,2] 蔡翔舟 戴志敏[1,2] LIN Ming;CHENG Maosong;CAI Xiangzhou;DAI Zhimin(Shanghai Institute of Applied Physics,Chinese Academy of Sciences,Shanghai 201800,China;University of Chinese Academy of Sciences,Beijing 100049,China)

机构地区：[1]中国科学院上海应用物理研究所,上海201800 [2]中国科学院大学,北京100049

出　　处：《核技术》2024年第9期141-150,共10页Nuclear Techniques

基　　金：中国科学院科技战略先导项目资助。

摘　　要：对于熔盐堆全堆高保真流体动力学计算,即使借助超级计算机的并行计算能力在面对快速甚至实时求解的问题仍然面临效率的巨大挑战,引入和采用模型降阶(Reduced Order Modeling,ROM)方法,将能够有效解决这类问题。基于本征正交分解(Proper Orthogonal Decomposition,POD)方法与Galerkin投影法,引入基于有限体积的模型降阶(ROM based on Finite Volume approximation,FV-ROM)方法和上确界稳定模型降阶(ROM with supremizer stabilization,SUP-ROM)方法,针对液态燃料熔盐堆(Liquid Fuel Molten Salt Reactor,LFMSR)层流和湍流瞬态工况开展适用性分析。结果表明:FV-ROM方法在速度误差和计算效率方面占有明显优势,层流和湍流瞬态速度平均L^(2)相对误差低于0.5%和0.6%,且单步长的加速比分别为1500和1000倍左右;相比之下,SUP-ROM方法在压力预测方面表现出显著的优势,层流和湍流瞬态压力平均L^(2)相对误差低至0.20%和0.38%。因此,通过FV-ROM和SUP-ROM两种方法相结合的方式进行熔盐堆流体动力学速度场和压力场预测,能够更加有效地提高流体动力学仿真的效率,并确保瞬态模拟过程计算可靠性和精确度。[Background]For high-fidelity simulations of fluid dynamics in molten salt reactor(MSR),even though a supercomputer is able to suppress the period of each simulation,the consequent expense is still prohibitively costly.A possible way to overcome this limitation is the use of Reduced Order Modelling(ROM)techniques.[Purpose]This study aims to evaluate the accuracy of the ROM methods for reconstructing the velocity and pressure fields.[Methods]Two ROM methods based on the Proper Orthogonal Decomposition(POD)with both Galerkin projection,namely FV-ROM(ROM based on Finite Volume approximation)and SUP-ROM(ROM with supremizer stabilization),were established for fluid dynamics of MSR.Then,both methods were tested on the unsteady cases of liquid-fueled molten salt reactor(LFMSR)for comparison and applicability analysis.[Results]The FV-ROM demonstrates notable advantages in both velocity prediction and computational efficiency.For laminar and turbulent transient simulations,the average velocity L^(2) relative errors are less than 0.5% and 0.6%,respectively,with acceleration ratios of approximately 1500 and 1000 times for single time steps.Conversely,the SUP-ROM scheme demonstrates significant prowess in pressure prediction,achieving remarkably low pressure average L^(2) relative errors of 0.20% and 0.38% for laminar and turbulent transient scenario,respectively.[Conclusions]Results of this study indicate that combination of SUP-ROM and FV-ROM for fluid dynamics computations of MSR can significantly enhance computational efficiency and ensure reliability and accuracy of transient simulation.

关 键 词：模型降阶 熔盐堆 FV-ROM SUP-ROM 流体动力学 

分 类 号：TL33[核科学技术—核技术及应用]