Study On The Numerical Methods Of System Transient Analysis Of High Temperature Reactor Direct Cycle

High temperature gas-cooled reactors gas turbine cycle (HTR-GT) sytem has the characteristics of inherent safety and high efficiency, and is promising Gen-VI reactor system.The transient characteristics of HTR-GT are very essential to its safety analysis and system control. In view of the insufficient study on the algorithms for solving transient compressible flow of the current system codes of HTR-GT, four algorithms are studied and compared for their performances in solving 1D transient compressible flow, namely the SIMPLE series algorithms, the semi-implicit algorithm, the nearly-implicit algorithm and the SETS algorithm.It was found that the existing algorithms are not capable of solving both the fast and slow transients accurately with fast computational time. To solve this problem, a hybrid semi-implicit algorithm (HSI) is proposed. The HSI algorithm is further validated via the benchmark shocktube problem and FLUENT simulations. The results show that the HSI is capable of capturing both the fast and slow transients with good stability, accuracy and computational time. It has good performance in solving the pressure transient, massflow transient and temperature transient. Based on the HSI algorithm, two methods were proposed to solve the strongly coupled heat exchanger in compressible flow, namely the decoupled method and half-coupled method. Both can successfully solve the coupled heat exchanger with temperature deviation less than 1 K. The decoupled method is 5/3 times as fast as the half-coupled method, and thus is more appropriate to be used in system analysis. To solve the whole-field system pressure simultaneously, a numerical mapping method was proposed and verified. This method is capable of solving the flow-information transfer mechanism between two adjacent components, so that all the flow parameters in the system can be solved simultaneously. Based on the work done above, a transient system solver for HTR-GT was studied. In the transient analysis of the linear power change transient of reactor core, the results show that this system solver can simulate both the fast and slow responses of HTR-GT.