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Non-Hermitian Delocalization in a Two-Dimensional Photonic Quasicrystal

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Physical Review Letters 2024年第26期132卷 263801-263801页

作者： Zhaoyang Zhang Shun Liang Ismaël Septembre Jiawei Yu Yongping Huang Maochang Liu Yanpeng Zhang Min Xiao Guillaume Malpuech Dmitry Solnyshkov Key Laboratory for Physical Electronics and Devices of the Ministry of Education & Shaanxi Key Lab of Information Photonic Technique School of Electronic Science and Engineering Faculty of Electronics and Information PHOTON-N2 Université Clermont Auvergne CNRS Clermont INP F-63000 Clermont-Ferrand France International Research Center for Renewable Energy and State Key Laboratory of Multiphase Flow in Power Engineering Department of Physics National Laboratory of Solid State Microstructures and School of Physics 75231 Paris France

Theoretical and experimental studies suggest that both Hermitian and non-Hermitian quasicrystals show localization due to the fractal spectrum and to the transition to diffusive bands via exceptional points, respectively. Here, we present an experimental study of a dodecagonal photonic quasicrystal based on electromagnetically induced transparency in a Rb vapor cell. First, we observe the suppression of the wave packet expansion in the Hermitian case. We then discover a new regime, where increasing the non-Hermiticity leads to delocalization, demonstrating that the behavior in non-Hermitian quasicrystals is richer than previously thought.

关键词： Electromagnetically induced transparency Localization Photonics Non-Hermitian systems Quasicrystals

Numerical Study of High-Energy Spark Ignition Characteristics in a Scramjet Combustor

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SSRN 2024年

作者： Gao, Ziyan Zhang, Meng Zhang, Zhibo Wu, Yun Zheng, Xing Miao, Huifeng National Key Lab of Aerospace Power System and Plasma Technology Xi’an Jiaotong University Xi’an710049 China State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong Universiy Xi’an710049 China National Key Lab of Aerospace Power System and Plasma Technology Air Force Engineering University Xi’an710038 China Shaanxi Key Laboratory of Environment and Control for Flight Vehicle School of Aerospace Engineering Xi’an Jiaotong University Shaanxi 710049 China

Reliable ignition is a fundamental prerequisite for the scramjet engines. In order to improve the reliability of ignition, further enhance the application of spark ignition in engineering, and improve the ignition ability in the field of supersonic combustion, an innovative long electrode distance high-energy spark igniter (LHSI) system was proposed by our research team. To reveal the instantaneous ignition characteristics of the LHSI, a simulation model of the LHSI is established and verified by experiments. Based on this, the formation and development of the initial fire core of vaporized kerosene and the ignition characteristics of LHSI in a scramjet combustor were simulated and compared with the conventional high-energy spark igniter (HSI). The analysis revealed that the success of the cavity ignition is greatly influenced by the local equivalent ratio of the initial flow field and the penetration depth of the initial flame core. Meanwhile, the fore recirculation zone of the cavity plays a key role in stabilization and development of the initial fire core. Compared with the HSI, the LHSI can produce initial flame core with higher penetration and greater size, which is the main reason for why LHSI has a broader ignition boundary. © 2024, The Authors. All rights reserved.

关键词： Ignition

Characterization of High-Performance Nanostructured Wick for Heat Pipes

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SSRN 2023年

作者： Sun, Qishi Han, Ruiyu Guo, Kailun Wang, Chenglong Zhang, Jing He, Xiaoqiang Qiu, Suizheng Su, Guanghui Tian, Wenxi Department of Nuclear Science and Technology State Key Lab. of Multiphase Flow in Power Engineering Shaanxi Key Lab. of Advanced Nuclear Energy and Technology Xi’an Jiaotong University Xi’an710049 China Key Lab. of Nuclear Reactor System Design Technology China Nuclear Power Research and Design Institute Chengdu610213 China

To investigate the best performance wick forms to support the design and fabrication of high-performance heat pipes, in this paper, two kinds of nanostructured wick were prepared by the oxidation-reduction method. The effect of surface nanostructure on the wick performance was investigated by comparing the surface characteristics, capillary properties, permeability, and evaporation properties. The result shows that the nanostructured wick presented excellent super hydrophilic properties. A liquid-lift visualization experimental method for measuring the capillary performance factor M was proposed, and it was verified to be correct by the separation effect of the capillary pumping experiment under a vacuum environment. With the increasing oxidized degree, the densification of nanoparticles on the wick surface increased the capillary performance factor M from 8.68 μm to 13.81 μm, with a maximum enhancement of 59.1%. The effective capillary radius decreased from 4.70×10-5 m to 4.01×10-5 m, with a maximum reduction of 14.9%. The permeability increased from 4.33×10-10 m2 to 5.83×10-10 m2, with a maximum enhancement of 34.7%. The increase in porosity made the effective capillary radius dominate the competition for permeability, and the capillary performance factor decreased by 17.1%. The thermal resistance of the wick decreased with the enhancement of the capillary performance factor, which fell from 2.03×10-3 m2·K/W to 1.26×10-3 m2·K/W. The current study provides a reference for the future design and preparation of high-performance heat pipe wicks. © 2023, The Authors. All rights reserved.

关键词： Heat resistance

Development and Verification of Safety Analysis Code to Model and Simulate Steam power Conversion System in Sodium-Cooled Fast Reactor

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SSRN 2023年

作者： Liu, Shuo Jin, Zhao Wang, Chenglong Zhang, Dalin Tian, Wenxi Qiu, Suizheng Su, Guanghui Yang, Jun School of Nuclear Science and Technology State Key Lab. of Multiphase Flow in Power Engineering Shaanxi Key Lab. of Advanced Nuclear Energy and Technology Xi’an Jiaotong University Shaanxi Xi’an710049 China China Institute of Atomic Energy Beijing102413 China

Sodium-cooled fast reactor (SFR) is one of the most promising generation IV reactor type. SFR system is composed of three heat transfer circuits. SFR will generate electricity, which requires accuracy prediction of steam power conversion system. Therefore, a one-dimensional thermal-hydraulic analysis code of the steam power conversion system of SFR has been developed. A modular modeling method was applied. Each equipment is packaged as a separate module. The system model can be obtained by connecting modules to achieve flexible modeling. Compared with RELAP5, the code uses a general algorithm to solve ODE, which enhances the universality of code. The model is verified with design results of Daya Bay Nuclear power Plant and BN-600 steam generator. The maximum relative errors for pressure and temperature are 5.44% and 2.40%, respectively. It is proven that the code developed can be used in the analysis and design the steam power conversion system. The steady-state analysis of SFR steam power conversion circuit is carried out. The design could provide a reference for the future development of steam power conversion system in SFR. © 2023, The Authors. All rights reserved.

关键词： Sodium-cooled fast reactors

Dynamic Modeling of Steam power Conversion System in Sodium-Cooled Fast Reactor

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SSRN 2023年

作者： Liu, Shuo Jin, Zhao Wang, Chenglong Zhang, Dalin Tian, Wenxi Qiu, Suizheng Su, G.H. Yang, Jun School of Nuclear Science and Technology State Key Lab. of Multiphase Flow in Power Engineering Shaanxi Key Lab. of Advanced Nuclear Energy and Technology Xi’an Jiaotong University Shaanxi Xi’an710049 China China Institute of Atomic Energy Beijing102413 China

Sodium-cooled fast reactor (SFR) is the most promising generation IV reactor type. SFR systems are composed of three heat transfer circuits. Currently, research on steam power conversion system is scarce because of complex structure. Therefore, a one-dimensional thermal-hydraulic analysis code of the steam power conversion system of SFR has been developed. Models of main components have been established, including once-through steam generator (OTSG), turbine, deaerator, feedwater heater, condenser, pump and moisture separator reheater (MSR). The model is verified with design results of Daya Bay Nuclear power Plant and BN-600 steam generator. The maximum relative errors for pressure and temperature are 5.44% and 2.40%, respectively. It is proven that the code developed can analysis and design the steam power conversion system. The steady-state analysis of SFR steam power conversion circuit is carried out. The design could provide a reference for the future development of steam power conversion system in SFR. © 2023, The Authors. All rights reserved.

关键词： Sodium-cooled fast reactors

Hydrodynamic and heat transfer properties of magnetic fluid in porous medium considering nanoparticle shapes and magnetic field-dependent viscosity

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Chinese Journal of Chemical engineering 2020年第2期28卷 329-339页

作者： Mohsen Izadi Masoud Javanahram Seyed Mohsen Hashem Zadeh Dengwei Jing Mechanical Engineering Department Lorestan UniversityKhorramabadIran Mechanical Engineering Department Islamic Azad UniversityBushehrIran Department of Mechanical Engineering Shahid Chamran University of AhvazIran School of Energy and Power Engineering State Key Lab of Multiphase Flow in Power EngineeringXi'an Jiaotong UniversityXi'an 710049China

The purpose of this paper is to study the characteristics of the combined convection heat transfer and a micropolar nanofluid flow passing through an impermeable stretching sheet in a porous *** nanofluid flow field is affected by a magnetic field perpendicular to the *** dynamic viscosity of the micropolar nanofluid changes under the influence of the magnetic *** continuity,linear momentum,angular momentum,and energy equations are first simplified using the order of magnitude technique that,along with the applied boundary conditions and the definition of the appropriate parameters,are transferred to the similarity space using the similarity *** the resulting equations are solved using the Runge–Kutta *** distinction of the macroscale and microscale flow fields and temperature fields resulting from different nanoparticle shapes was *** the Hartmann number,the vortex viscosity parameter,the magnetic parameter,the nanoparticle volume fraction,and the permeability parameter of the porous media increased the surface friction on the *** the vortex viscosity parameter,the magnetic parameter,and the volume fraction of the nanoparticles increases the Nusselt number.

关键词： MHD-combined convection Porous media Magnetic micropolar nanofluid

Experimental Study on Leakage of High-Energy Fluids Through Narrow Elliptical Slits

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SSRN 2024年

作者： Bi, Qincheng Zhang, Tao Zhao, Jinle Wang, Teng Yang, Zhendong Gui, Miao State Key Lab Multiphase Flow Power Engn Xi'an Jiaotong University Shaanxi Xian710049 China Department of Power Engineering North China Electric Power University Baoding071003 China State Key Laboratory of Eco-hydraulics in Northwest Arid Region of China Xi'an University of Technology Shaanxi Xian710048 China School of Nuclear Science and Technology Xi'an Jiaotong University Shaanxi Xian710049 China

This study is focused on the leakage flow rate of high-energy fluid passing through narrow elliptical slits with large aspect ratios, which is an issue in the application of the leak-before-break concept. Experiments were conducted using a high-temperature and high-pressure experimental platform at Xi’an Jiaotong University, where the temperature reached up to 320 ℃ and the pressure reached up to 10 MPa. These temperatures and pressures encompass a wide range of operating conditions (single-phase cold water, liquid-vapor (two-phase) mixture, and superheated steam). A series of narrow elliptical slits with different aspect ratios (528-2083) and hydraulic diameters (226-412 um) were used in the experiments. The experimental results were compared with previous model. Based on the experimental data and the the effects of the aspect ratio, the mathematical model was corrected, and the results obtained from the modified model conform well with the experimental results. © 2024, The Authors. All rights reserved.

关键词： Aspect ratio

Validation of Lead-Bismuth Thermal Hydraulic Facilities Based on Modified Relap5

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SSRN 2022年

作者： Zhang, Yixin Zhang, Jiaxin Wang, Chenglong Tian, Wenxi Qiu, Suizheng Su, G.H. Department of Nuclear Science and Technology State Key Lab. of Multiphase Flow in Power Engineering Shaanxi Key Lab. of Advanced Nuclear Energy and Technology Xi’an Jiaotong University Xi'An710049 China

On the basis of not affecting the original computing power of RELAP5, the physical properties of lead and bismuth are added and verified. The important content of this paper is to use the modified RELAP5 to simulate the transient operating conditions carried out on the three lead-bismuth eutectic experimental devices of NACIE, TALL and NCCL, and compare it with the experimental data. The results show that the temperature error of the heating section of the NACIE facility under transient power conditions is within 7%. The error between the calculated value and the experimental value of the final core temperature under each working condition of the TALL facility is within 5%. The temperature simulation error of the experimental section of the NCCL circular tube heat transfer test is within 4%. The research in this paper can provide data and verification support for the development of the lead-bismuth fast reactor project. © 2022, The Authors. All rights reserved.

关键词： Fast reactors

Numerical Study on Thermal-Hydraulic Characteristics of Lead-Bismuth Loop System Under Moving Conditions

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SSRN 2022年

作者： Yuan, Lanfei Wang, Chenglong Liu, Zhipeng Tian, Wenxi Qiu, Suizheng Su, G.H. Department of Nuclear Science and Technology State Key Lab. of Multiphase Flow in Power Engineering Shaanxi Key Lab. of Advanced Nuclear Energy and Technology Xi’an Jiaotong University Shaanxi Xi'An710049 China

The investigation of flow and heat transfer of lead-bismuth eutectic (LBE) under moving conditions is vital to the design optimization of LBE loop system in offshore engineering. In this paper, the calculation model of lead-bismuth loop system and the calculation method of moving conditions are developed by using commercial CFD software, and experiments were carried out to verify the numerical results. The calculation results demonstrate that the moving conditions will cause periodic fluctuations in the natural circulation flow rate of the loop system. The period of the flow rate fluctuation is consistent with the motion period, and the amplitude of the fluctuation will increase with the increase of the maximum range of motion and the decrease of the motion period. When the maximum heaving amplitude is 0.3m and the period is 8s, the instantaneous fluctuation of the flow rate reaches a maximum of 0.8%, and the reverse flow phenomenon occurs under rolling motion. Rolling and heaving motion also make heat transfer characteristic parameters of the system have periodic instantaneous fluctuation. The maximum instantaneous fluctuation of Nu number reaches 4.63%, and the maximum time average Nu can reach -2.15% under heaving motion of 0.3m-8s. In addition, the influence of rolling on system parameters is more severe than that of heaving. These results obtained in this study have important engineering application value for the design of LBE loop system under moving conditions. © 2022, The Authors. All rights reserved.

关键词： Computational fluid dynamics