Analysis of sub- and supercritical Hopf bifurcation with a reduced order model in natural circulation loop

The prime objective of the work is to carry out bifurcation analysis of a single channel natural circulation loop having high system pressure. The objective is achieved in two steps. First step is to perform linear stability analysis of the system with the state space approach. The analysis is used to obtain stability maps in Npch and Nsub plane. In the second step, limited time series analysis is carried out numerically in the vicinity of the obtained stability boundaries. This analysis leads to delineation of bifurcation characteristics of the system namely subcritical and supercritical bifurcations. The existence of limit cycles and their behavior are also presented. The effects of different design parameters on the aforementioned bifurcation phenomena are shown. It is observed that, these bifurcation phenomena are quite sensitive to the design parameters. The reduced order model used in the present work has been developed by keeping a new insight to include the density variation in single phase and the drift flux correlations in the two-phase.