With the development of the GEN-IV nuclear reactors in the 21st Century, as a substitute for the steam cycle, the supercritical carbon dioxide (SCO2) Brayton cycle has been widely used in a variety of power generation scenarios and has attracted widely attention from the scholars. However, the previous research mainly focused on the basic thermodynamics research, parameter optimizations and system design. Considering the load variability and control flexibility of the power generation system, the dynamic performance research of the SCO2 cycle is necessary. In the numerous layouts of SCO2 Brayton cycle, the SCO2 simple recuperated cycle stands out for its simple structure and high efficiency, which is also the main focus in this paper. In this paper, a dynamic model of SCO2 simple recuperated brayton cycle is developed with the Simulink software. The overall system includes a turbine (T), compressor (CM), regenerator (Re), intermediate heat exchanger (IHE), pre-cooler (PC), surge tank (ST), and heater. The models could be able to realize independent physical functions and be mathematically independent. The SCO2 recuperated cycle is then built with the developed models. Based on the simple recuperated system, the comparative calculation with the design value is carried out to verify the models and the results are very positive. Since the components are tightly coupled in the closed-loop cycle, the error of the main parameters for each component is relatively large. In the steady calculation, the maximum error of the component parameter is 7.72%, and the error of the cycle efficiency is about 1.45%. The results are very promising that the developed model has the ability to evaluate the thermal-hydraulic characteristics of the SCO2 Brayton circulation system.

The supercritical carbon dioxide (SCO2) Brayton cycle has the characteristics of high power density and high thermal efficiency, which is an important development direction of the micro power plant. SCO2 turbine is the core component of the SCO2 Brayton cycle of which the dynamics have important influences on operational reliability of the entire system. With regard to the rotor of SCO2 turbine, the equations of motion is established by adopting finite element method. The complex eigenvalues of the rotor are solved in the state space, and the campbell diagram has been drawn to obtain the critical speeds. The steady state response of the rotor is obtained by the harmonic balance method, and the safety of the system is estimated based on API684. Results show that the rotor is not safe with its original geometric paramters. Aiming to improve the operational safety, an optimization method based on active learning is developed to maximize the separation margin. Results show that after the optimization, the separation margin has been greatly increased. Comparing with the genetic algorithm (GA) and the parttern search (PS) method, the iteration number of the active learning optimization method has been greatly reduced. The effectiveness of the developed optimization method is proved, and the study method and conclusions can serve as a reference to the optimization of SCO2 turbine rotors in the industry.

In addition to the traditional performance indexes such as heat exchange efficiency and flow resistance, the design of nuclear heat exchange tube needs to take into account the flow noise level index of heat exchange tube at the same time. Therefore, the design of heat exchange tube needs to consider multiple properties such as heat exchange efficiency, flow resistance and flow noise at the same time, which greatly increases the complexity of nuclear heat exchange tube design. In this paper, a design method of low-noise nuclear heat exchange tube is proposed. The design parameters of nuclear heat exchange tube are automatically adjusted based on the coupling of multiple simulation software. The heat exchange efficiency, flow resistance and flow noise of nuclear heat exchange tube are characterized by normalizing the comprehensive evaluation factor of flow and heat transfer and insertion loss, and the optimal design parameters of nuclear heat exchange tube are found through orthogonal test.

As an important structure in turbine machinery, grouped blades are easy to damage due to large thermal loads and centrifugal loads. Once the characteristic frequency of grouped blades is equal to or close to the frequency of the exciting forces, the vibration of the grouped blades will become very severe. Therefore, it is very important to analyze the characteristic frequency of grouped blades accurately and quickly. This article aims to investigate the model reduction method of grouped blades, which can reduce the unknowns in the dynamic equations of grouped blades. And the efficiency of the modal analysis of grouped blades can be improved. Finally, the effects of the modal truncation number on the error of the natural frequency, the modal shape confidence factor, and the calculation time are discussed. Although the structure discussed in this paper is the disk with three blades, the derived algorithm can be applied to large-scale grouped blades. The study of this paper can serve as a reference for the design and validation of the widely used blade groups in the industry.

The simulation analysis model of the concrete experimental foundation platform is constructed by the method of three-dimensional computer-aided design (3D CAD) and three-dimensional computer-aided engineering (3D CAE). The influence of the slotting depth and width on the concrete structure’s vibration isolation performance is analyzed in detail. The results show that as the slotting depth increases from 0 m to 4 m, the total vibration acceleration level of the concrete inner side structure decreases by 12.27 dB. The vibration isolation performance of the foundation platform is highly sensitive to the slotting depth. As the slotting width increases from 0.5 m to 2 m, the total vibration acceleration level of the concrete inner side structure is always maintained within the range of 8.8 dB–8.9 dB. The total vibration acceleration level of the foundation platform changes little. Vibration isolation performance shows low sensitivity to the slotting width.