In this study

a numerical model that applies time-domain method is established to analyze the flow instability of a uniformly heated parallel-channel system. On the basis of program verification

the nonlinear dynamics of the fluid in water wall of ultra-supercritical circulating fluidized bed(CFB) boilers are discussed. The results show that

the fluctuating trend of the mass flow at inlet and outlet of the chanel is in inverse distribution. The mass flow rates with heat flux perturbations imposed on either single channel decline gradually with time

suggesting that flow stability can be maintained under normal full load condition. In addition

the effects of heat flux perturbation on transient responses of the typical parallel channels are studied. The results illustrate that the maximum of the inlet mass flow rate in both channels are high when perturbation is imposed on a strong heated channel. Moreover

flow in the stronger heated channel reveals more remarkable dynamic characteristics than in the weaker one. Furthermore

data at different inlet temperatures and mass flow rates are calculated to generate the dimensionless instability boundary. The results show that

when the inlet temperature is low

the inlet mass flow rate should be increased to stabilize the system. Otherwise

the effect of the mass flow rate on the instability boundary is almost negligible.