Study on flow stability margin by method of system identification

The main objective of the investigation is to develop a practical technolog y and method in engineering based on general control theory, for distinguis hing two-phase flow stability and identifying the safety margin by using th e system identification method By combining the two-phase flow stability th eory in the thermo-physics field with the system stability theory and the s ystem identification method in the field of information science, a thermo-h ydraulic experiment technology with a new concept was developed The experim ent was carried out on the thermo-hydraulic test system HRTL-5 which serves as simulator to the primary circulation of the nuclear heating reactor NHR -5 and was used for investigation on its thermophysical behavior Reverse re pent pseudo-random sequences which were added to the steady hear flux as in put signal sources and measured flow rates as response function were used i n the test. The two-phase flow stability and the stability margin of the na tural circulation system were investigated by analyzing the system pulse re sponse fraction, the decay ratio and the stability boundary under different operational conditions. The results are compared with those obtained by us ing conventional methods. The test method and typical results obtained are presented in this paper.