The reactor coolant pump(RCP)rotor seizure accident is defined as a short-time seizure of the RCP rotor.This event typically leads to an abrupt flow decrease in the corresponding loop and an ensuing reactor and turbin...The reactor coolant pump(RCP)rotor seizure accident is defined as a short-time seizure of the RCP rotor.This event typically leads to an abrupt flow decrease in the corresponding loop and an ensuing reactor and turbine trip.The significant reduction of core coolant flow while the reactor is being operated at full load can have very negative consequences.This potentially dangerous event is typically characterized by a complex transient behavior in terms of flow conditions and energy transformation,which need to be analyzed and understood.This study constructed transient flow and rotational speed mathematical models under various degrees of rotor seizure using the test data collected from a dedicated transient rotor seizure test system.Then,bidirectional fluid-solid coupling simulations were conducted to investigate the flow evolution mechanism.It is found that the influence of the impeller structure size and transient braking acceleration on the unsteady head(Hu)is dominant in rotor seizure accident events.Moreover,the present results also show that the rotational acceleration additional head(Hu1)is much higher than the instantaneous head(Hu2).展开更多
Successfully utilized non-axisymmetric endwalls to enhance turbine efficiencies(aerodynamic and turbine inlet temperatures)by controlling the characteristics of the secondary flow in a blade passage.This is accomplish...Successfully utilized non-axisymmetric endwalls to enhance turbine efficiencies(aerodynamic and turbine inlet temperatures)by controlling the characteristics of the secondary flow in a blade passage.This is accomplished by steady-state numerical hydrodynamics and deep knowledge of the field of flow.Because of the interaction between mainstream and purge flow contributing supplementary losses in the stage,non-axisymmetric endwalls are highly susceptible to the inception of purge flow exit compared to the flat and any advantage rapidly vanishes.The conclusions reveal that the supreme endwall pattern could yield a lowering of the gross pressure loss at the design stage and is related to the size of the top-loss location being productively lowered.This has led to diminished global thermal exchange lowered in the passage of the vane alone.The reverse flow adjacent to the suction side corner of the endwall is migrated farther from the vane surface,as the deviated pressure spread on the endwall accelerates the flow and progresses the reverse flow core still downstream.The depleted association between the tornado-like vortex and the corner vortex adjacent to the suction side corner of the endwall is the dominant mechanism of control in the contoured end wall.In this publication,we show that the non-axisymmetric endwall contouring by selective numerical shape change method at most prominent locations is advantageous in lowering the thermal load in turbines to augment the net heat flux reduction as well as the aerodynamic performance using multi-objective optimization.展开更多
随着中国能源结构深化改革的推进,积极发展核能已成为主要趋势。第四代核能系统代表着核电发展的趋势和技术前沿,因此铅冷快中子反应堆的研究在国际上备受关注。基于麻省理工学院(Massachusetts Institute of Technology,MIT)开发的反...随着中国能源结构深化改革的推进,积极发展核能已成为主要趋势。第四代核能系统代表着核电发展的趋势和技术前沿,因此铅冷快中子反应堆的研究在国际上备受关注。基于麻省理工学院(Massachusetts Institute of Technology,MIT)开发的反应堆蒙特卡洛中子输运方程开源软件OpenMC,以铅冷快中子欧洲示范堆(advanced lead fast reactor European demonstrator,ALFRED)为研究对象,选取两种不同的堆芯冷却剂开展铅冷快堆堆芯物理计算。结果表明:在装载相同燃料的情况下,采用铅-铋冷却剂可以提高堆芯的初始反应性271×10-5;堆芯在正常商运状态下具有更高的堆芯有效缓发中子份额;堆芯的中子能谱更宽、更硬;对于燃料中的239 Pu核素,燃烧效果更好。因此,ALFRED堆芯采用铅-铋合金冷却剂时,具有更高的有效增殖因子,有望提高堆芯的控制性和燃耗性能,并有效减少放射性废物的产生。研究成果为铅冷快中子反应堆欧洲示范堆堆芯设计和性能优化提供了有益的参考。展开更多
基金National Natural Science Foundation Joint Fund Key Project(U20A20292)Task Book for Shandong Provincial Science and Technology Small and Medium-Sized Enterprise Innovation Capability Enhancement Engineering Project(2023TSGC0005).
文摘The reactor coolant pump(RCP)rotor seizure accident is defined as a short-time seizure of the RCP rotor.This event typically leads to an abrupt flow decrease in the corresponding loop and an ensuing reactor and turbine trip.The significant reduction of core coolant flow while the reactor is being operated at full load can have very negative consequences.This potentially dangerous event is typically characterized by a complex transient behavior in terms of flow conditions and energy transformation,which need to be analyzed and understood.This study constructed transient flow and rotational speed mathematical models under various degrees of rotor seizure using the test data collected from a dedicated transient rotor seizure test system.Then,bidirectional fluid-solid coupling simulations were conducted to investigate the flow evolution mechanism.It is found that the influence of the impeller structure size and transient braking acceleration on the unsteady head(Hu)is dominant in rotor seizure accident events.Moreover,the present results also show that the rotational acceleration additional head(Hu1)is much higher than the instantaneous head(Hu2).
文摘Successfully utilized non-axisymmetric endwalls to enhance turbine efficiencies(aerodynamic and turbine inlet temperatures)by controlling the characteristics of the secondary flow in a blade passage.This is accomplished by steady-state numerical hydrodynamics and deep knowledge of the field of flow.Because of the interaction between mainstream and purge flow contributing supplementary losses in the stage,non-axisymmetric endwalls are highly susceptible to the inception of purge flow exit compared to the flat and any advantage rapidly vanishes.The conclusions reveal that the supreme endwall pattern could yield a lowering of the gross pressure loss at the design stage and is related to the size of the top-loss location being productively lowered.This has led to diminished global thermal exchange lowered in the passage of the vane alone.The reverse flow adjacent to the suction side corner of the endwall is migrated farther from the vane surface,as the deviated pressure spread on the endwall accelerates the flow and progresses the reverse flow core still downstream.The depleted association between the tornado-like vortex and the corner vortex adjacent to the suction side corner of the endwall is the dominant mechanism of control in the contoured end wall.In this publication,we show that the non-axisymmetric endwall contouring by selective numerical shape change method at most prominent locations is advantageous in lowering the thermal load in turbines to augment the net heat flux reduction as well as the aerodynamic performance using multi-objective optimization.
文摘随着中国能源结构深化改革的推进,积极发展核能已成为主要趋势。第四代核能系统代表着核电发展的趋势和技术前沿,因此铅冷快中子反应堆的研究在国际上备受关注。基于麻省理工学院(Massachusetts Institute of Technology,MIT)开发的反应堆蒙特卡洛中子输运方程开源软件OpenMC,以铅冷快中子欧洲示范堆(advanced lead fast reactor European demonstrator,ALFRED)为研究对象,选取两种不同的堆芯冷却剂开展铅冷快堆堆芯物理计算。结果表明:在装载相同燃料的情况下,采用铅-铋冷却剂可以提高堆芯的初始反应性271×10-5;堆芯在正常商运状态下具有更高的堆芯有效缓发中子份额;堆芯的中子能谱更宽、更硬;对于燃料中的239 Pu核素,燃烧效果更好。因此,ALFRED堆芯采用铅-铋合金冷却剂时,具有更高的有效增殖因子,有望提高堆芯的控制性和燃耗性能,并有效减少放射性废物的产生。研究成果为铅冷快中子反应堆欧洲示范堆堆芯设计和性能优化提供了有益的参考。
