Study on flow characteristics in LBE-cooled main coolant pump under positive rotating condition

Lu Yonggang,Wang Zhengwei,Zhu Rongsheng,Wang Xiuli,Long Yun 한국원자력학회 2022 Nuclear Engineering and Technology Vol.54 No.7

The Generation IV Lead-cooled fast reactor (LFR) take the liquid lead or lead-bismuth eutectic alloy (LBE) as the coolant of the primary cooling circuit. Combined with the natural characteristics of lead alloy and the design features of LFR, the system is the simplest and the number of equipment is the least, which reflects the inherent safety characteristics of LFR. The nuclear main coolant pump (MCP) is the only power component and the only rotating component in the primary circuit of the reactor, so the various operating characteristics of the MCP are directly related to the safety of the nuclear reactor. In this paper, various working conditions that may occur in the normal rotation (positive rotating) of the MCP and the corresponding internal flow characteristics are analyzed and studied, including the normal pump condition, the positive-flow braking condition and the negative-flow braking condition. Since the corrosiveness of LBE is proportional to the fluid velocity, the distribution of flow velocity in the pump channel will be the focus of this study. It is found that under the normal pump condition and positive-flow braking conditions, the high velocity region of the impeller domain appears at the inlet and outlet of the blade. At the same radius, the pressure surface is lower than the back surface, and with the increase of flow rate, the flow separation phenomenon is obvious, and the turbulent kinetic energy distribution in impeller and diffuser domain shows obvious near-wall property. Under the negative-flow braking condition, there is obvious flow separation in the impeller channel.

A study of hydroelastic behavior of hinged VLFS

Yonggang Sun,Da Lu,Jin Xu,Xiantao Zhang 대한조선학회 2018 International Journal of Naval Architecture and Oc Vol.10 No.2

This paper introduces a new method to study the hydroelastic behavior of hinged Very Large Floating Structures (VLFSs). A hinged twomodule structure is used to confirm the present approach. For each module, the hydroelasticity theory proposed by Lu et al. (2016) is adopted to consider the coupled effects of wave dynamics and structural deformation. The continuous condition at the connection position between two adjacent modules is also satisfied. Then the hydroelastic motion equation can be established and numerically solved to obtain the vertical displacement, force and bending moment of the hinged structure. The results calculated by the present new method are compared with those obtained using three-dimensional hydroelasticity theory (Fu et al., 2007), which shows rather good agreement.

Research on the structure design of the LBE reactor coolant pump in the lead base heap

Yonggang Lu,Rongsheng Zhu,Qiang Fu,Xiuli Wang,Ce An,Jing Chen 한국원자력학회 2019 Nuclear Engineering and Technology Vol.51 No.2

Since the first nuclear reactor first critical, nuclear systems has gone through four generations of history,and the fourth generation nuclear system will be truly realized in the near future. The notions of SVBRand lead-bismuth eutectic alloy coolant put forward by Russia were well received by the internationalnuclear science community. Lead-bismuth eutectic alloy with the ability of the better neutron economy,the low melting point, the high boiling point, the chemical inertness to water and air and other features,which was considered the most promising coolant for the 4th generation nuclear reactors. This studymainly focuses on the structural design optimization of the 4th-generation reactor coolant pump,including analysis of external characteristics, inner flow, and transient characteristic. It was found that:the reactor coolant pump with a central symmetrical dual-outlet volute structure has better radialdirectionbalance, the pump without guide vane has better hydraulic performance, and the pumpwith guide vanes has worse torsional vibration and pressure pulsation. This study serves as experienceaccumulation and technical support for the development of the 4th generation nuclear energy system.

Comparative analysis of internal flow characteristics of LBE-cooled fast reactor main coolant pump with different structures under reverse rotation accident conditions

Lu, Yonggang,Wang, Xiuli,Fu, Qiang,Zhao, Yuanyuan,Zhu, Rongsheng Korean Nuclear Society 2021 Nuclear Engineering and Technology Vol.53 No.7

Lead alloy is used as coolant in Lead-based cooled Fast Reactor (LFR). The natural characteristics of lead alloy are combined with the simple structural design of LFR. This constitutes the inherent safety characteristics of LFR. The main work of this paper is to take the main coolant pump (MCP) in the lead-cooled fast reactor (LFR) as the research object, and to study the flow pattern distribution of the internal flow field under the reverse rotation pump condition, the reverse rotation positive-flow braking condition and the reverse rotation negative-flow braking condition. In this paper, the double-outlet volute type and the space guide vane are selected as the potential designs of the CLEAR-I MCP. In this paper, the CFD method is used to study the potential reverse accident of the MCP. It is found that the highest flow velocity in the impeller appears at the impeller outlet, and the Q-H curves of the two design programs basically coincide. The space guide vane type MCP has better hydraulic performance under the reverse rotation positive-flow condition, the Q-H curves of the two designs gradually separate with increasing flow rate, and the maximum flow velocity inside the space guide vane type MCP is obviously lower than that of the double-outlet volute type. For the reverse rotation test of MCP, only the condition of the forward rotating pump of the main coolant pump is tested and verified. For the simulation of the MCP in LBE medium, it proved that the turbulence model and basic settings selected in the simulation are reliable.

A study of hydroelastic behavior of hinged VLFS

Sun, Yonggang,Lu, Da,Xu, Jin,Zhang, Xiantao The Society of Naval Architects of Korea 2018 International Journal of Naval Architecture and Oc Vol.10 No.2

This paper introduces a new method to study the hydroelastic behavior of hinged Very Large Floating Structures (VLFSs). A hinged two-module structure is used to confirm the present approach. For each module, the hydroelasticity theory proposed by Lu et al. (2016) is adopted to consider the coupled effects of wave dynamics and structural deformation. The continuous condition at the connection position between two adjacent modules is also satisfied. Then the hydroelastic motion equation can be established and numerically solved to obtain the vertical displacement, force and bending moment of the hinged structure. The results calculated by the present new method are compared with those obtained using three-dimensional hydroelasticity theory (Fu et al., 2007), which shows rather good agreement.

Neonatal Immune State Is Influenced by Maternal Allergic Rhinitis and Associated With Regulatory T cells

Lu Tan,Jing Ou,Zezhang Tao,Yonggang Kong,Yuxuan Zhang 대한천식알레르기학회 2017 Allergy, Asthma & Immunology Research Vol.9 No.2

Purpose: Maternal influences contribute to the origin of allergic diseases, but the mechanisms are not clear. The current literature prompted the role of epigenetics in the development of allergic diseases. We sought to investigate the roles of regulatory T (Treg) cells and Forkhead box p3 (Foxp3) DNA methylation in the process of maternal transmission of allergic rhinitis (AR) susceptibility. Methods: BALB/c female mice (AR mother) were sensitized by intraperitoneal injection of Dermatophagoides pteronyssinus (Der p) 1 on day 1 and 7. Then they mated with normal male mice on day 8. From day 21 to 28, the female mice were intranasal challenged with Der p 1 continuously. The normal controls were given with normal saline in the same way. On postnatal day 3, Female mice and their offspring were sacrificed to detect their histopathology in nasal mucosae, cytokines in sera of mother and spleen homogenates of offspring, Treg cells count, Foxp3 mRNA expressions, and Foxp3 DNA methylation levels in spleens. Results: Compared with the normal controls, neonatal offspring of Der p 1-stimulated female mice (AR offspring) showed the elevation of interleukin (IL)-4 (P<0.01) and IL-17 (P<0.01), the submission of IL-10 (P<0.01) in spleen homogenates. Further, Treg cells count in AR offspring decreased remarkably compared with the normal offspring (P<0.01). Though the difference of Foxp3 DNA methylation level between AR offspring and normal control offspring was not obvious, correlation analysis demonstrated that there was significantly positive correlation between Foxp3 DNA methylation level of mother and that of offspring (r=0.803, P<0.01). Conclusions: Under the influence of Maternal AR, their neonatal offspring develop into T-helper type 2 (Th2) dominant immune state, which is closely associated with the recession of Treg cells. Foxp3 DNA methylation may be a mechanism responsible for that maternal effect but still need more studies to ensure.

Study on bidirectional fluid-solid coupling characteristics of reactor coolant pump under steady-state condition

Xiuli Wang,Yonggang Lu,Rongsheng Zhu,Qiang Fu,Haoqian Yu,Yiming Chen 한국원자력학회 2019 Nuclear Engineering and Technology Vol.51 No.7

The AP1000 reactor coolant pump is a vertical shielded-mixed flow pump, is the most important coolant power supply and energy exchange equipment in nuclear reactor primary circuit system, whose steady-state and transient performance affect the safety of the whole nuclear island. Moreover, safety demonstration of reactor coolant pump is the most important step to judge whether it can be practiced, among which software simulation is the first step of theoretical verification. This paper mainly introduces the fluid-solid coupling simulation method applied to reactor coolant pump, studying the feasibility of simulation results based on workbench fluid-solid coupling technology. The study found that: for the unsteady calculations of the pure liquid media, the average head of the reactor coolant pump with bidirectional fluid-solid coupling decreases to a certain extent. And the coupling result is closer to the real experimental value. The large stress and deformation of rotor under different flow conditions are mainly distributed on impeller and idler, and the stress concentration mainly occurs at the junction of front cover plate and blade outlet. Among the factors that affect the dynamic stress change of rotor, the pressure load takes a dominant position.

Materials for stretchable electronics in bioinspired and biointegrated devices

Kim, Dae-Hyeong,Lu, Nanshu,Huang, Yonggang,Rogers, John A. Cambridge University Press (Materials Research Soc 2012 MRS bulletin Vol.37 No.3

<▼1><B>Abstract</B><P/></▼1><▼2><P>Inorganic semiconductors such as silicon, gallium arsenide, and gallium nitride provide, by far, the most well-established routes to high performance electronics/optoelectronics. Although these materials are intrinsically rigid and brittle, when exploited in strategic geometrical designs guided by mechanics modeling, they can be combined with elastomeric supports to yield integrated devices that offer linear elastic responses to large strain (∼100%) deformations. The result is an electronics/optoelectronics technology that offers the performance of conventional wafer-based systems, but with the mechanics of a rubberband. This article summarizes the key enabling concepts in materials, mechanics, and assembly and illustrates them through representative applications, ranging from electronic “eyeball” cameras to advanced surgical devices and “epidermal” electronic monitoring systems.</P></▼2>

Running city game optimizer: a game-based metaheuristic optimization algorithm for global optimization

Ma Bing,Hu Yongtao,Lu Pengmin,Liu Yonggang 한국CDE학회 2023 Journal of computational design and engineering Vol.10 No.1

As science and technology improve, more and more complex global optimization difficulties arise in real-life situations. Finding the most perfect approximation and optimal solution using conventional numerical methods is intractable. Metaheuristic optimization approaches may be effective in achieving powerful global optimal solutions for these complex global optimization situations. Therefore, this paper proposes a new game-based algorithm called the running city game optimizer (RCGO), which mimics the game participant’s activity of playing the running city game. The RCGO is mathematically established by three newfangled search strategies: siege, defensive, and eliminated selection. The performance of the proposed RCGO algorithm in optimization is comprehensively evaluated on a set of 76 benchmark problems and 8 engineering optimization scenarios. Statistical and comparative results show that RCGO is more competitive with other state-of-the-art competing approaches in terms of solution quality and convergence efficiency, which stems from a proper balance between exploration and exploitation. Additionally, in the case of engineering optimization scenarios, the proposed RCGO is able to deliver superior fitting and occasionally competitive outcomes in optimization applications. Thus, the proposed RCGO is a viable optimization tool to easily and efficiently handle various optimization problems.

Complete Genome Sequencing of Bacillus velezensis WRN014, and Comparison with Genome Sequences of other Bacillus velezensis Strains

( Junru Wang ),( Juyuan Xing ),( Jiangkun Lu ),( Yingjiao Sun ),( Juanjuan Zhao ),( Shaohua Miao ),( Qin Xiong ),( Yonggang Zhang ),( Guishan Zhang ) 한국미생물생명공학회(구 한국산업미생물학회) 2019 Journal of microbiology and biotechnology Vol.29 No.5

Bacillus velezensis strain WRN014 was isolated from banana fields in Hainan, China. Bacillus velezensis is an important member of the plant growth-promoting rhizobacteria (PGPR) which can enhance plant growth and control soil-borne disease. The complete genome of Bacillus velezensis WRN014 was sequenced by combining Illumina Hiseq 2500 system and Pacific Biosciences SMRT high-throughput sequencing technologies. Then, the genome of Bacillus velezensis WRN014, together with 45 other completed genome sequences of the Bacillus velezensis strains, were comparatively studied. The genome of Bacillus velezensis WRN014 was 4,063,541bp in length and contained 4,062 coding sequences, 9 genomic islands and 13 gene clusters. The results of comparative genomic analysis provide evidence that (i) The 46 Bacillus velezensis strains formed 2 obviously closely related clades in phylogenetic trees. (ii) The pangenome in this study is open and is increasing with the addition of new sequenced genomes. (iii) Analysis of single nucleotide polymorphisms (SNPs) revealed local diversification of the 46 Bacillus velezensis genomes. Surprisingly, SNPs were not evenly distributed throughout the whole genome. (iv) Analysis of gene clusters revealed that rich gene clusters spread over Bacillus velezensis strains and some gene clusters are conserved in different strains. This study reveals that the strain WRN014 and other Bacillus velezensis strains have potential to be used as PGPR and biopesticide.