The method of characteristic(MOC) was adopted to analyze the check valve-induced water hammer behaviors for a Parallel Pumps Feedwater System(PPFS) during the alternate startup process.The motion of check valve disc w...The method of characteristic(MOC) was adopted to analyze the check valve-induced water hammer behaviors for a Parallel Pumps Feedwater System(PPFS) during the alternate startup process.The motion of check valve disc was simulated using inertial valve model.Transient parameters including the pressure oscillation,local flow velocity and slamming of the check valve disc etc.have been obtained.The results showed that severe slamming between the valve disc and valve seat occurred during the alternate startup of parallel pumps.The induced maximum pressure vibration amplitude is up to 5.0 MPa.The scheme of appending a damping torque to slow down the check valve closing speed was also performed to mitigate of water hammer.It has been numerically approved to be an effective approach.展开更多
Based on the experiment of onset of nucleate boiling(ONB)in natural circulation and the nonequilibrium thermodynamics dissipative theory,the mechanism of ONB in narrow rectangle channels of natural circulation is prop...Based on the experiment of onset of nucleate boiling(ONB)in natural circulation and the nonequilibrium thermodynamics dissipative theory,the mechanism of ONB in narrow rectangle channels of natural circulation is proposed.It points out that the onset of nucleate boiling is influenced by the degree of superheat and the special conditions of narrow channels.Under the conditions of both density difference in natural circulation and narrow rectangle channels,the prediction model of ONB in natural circulation of narrow channels based on fluctuating is established.The experimental results show that the present model can be used to predict the heat flux of ONB in narrow rectangle channels.Features of ONB in natural circulation narrow rectangle channels are as follows:heating power is the incentive of the happen of ONB;the higher the heating power is,the higher the degree of superheat is,and the earlier the ONB will appear.With the pressurizing,the appearance of ONB will be delayed.The higher the degree of supercooling is,the later the ONB appears.The ONB will happen easier when there are noncondensable gases and roughness in the channels.展开更多
基金Supported by the national key laboratory on Bubble Physics and Natural Circulation (BNPC)the Program for New Century Excellent Talents in University (NCET-06-0837)
文摘The method of characteristic(MOC) was adopted to analyze the check valve-induced water hammer behaviors for a Parallel Pumps Feedwater System(PPFS) during the alternate startup process.The motion of check valve disc was simulated using inertial valve model.Transient parameters including the pressure oscillation,local flow velocity and slamming of the check valve disc etc.have been obtained.The results showed that severe slamming between the valve disc and valve seat occurred during the alternate startup of parallel pumps.The induced maximum pressure vibration amplitude is up to 5.0 MPa.The scheme of appending a damping torque to slow down the check valve closing speed was also performed to mitigate of water hammer.It has been numerically approved to be an effective approach.
基金Supported by National Natural Science Foundation of China(No.50976033)National Key Laboratory of Bubble Physics and Natural Circulation(No.9140C7 101030905)North China Electric Power University’s 211 Project
文摘Based on the experiment of onset of nucleate boiling(ONB)in natural circulation and the nonequilibrium thermodynamics dissipative theory,the mechanism of ONB in narrow rectangle channels of natural circulation is proposed.It points out that the onset of nucleate boiling is influenced by the degree of superheat and the special conditions of narrow channels.Under the conditions of both density difference in natural circulation and narrow rectangle channels,the prediction model of ONB in natural circulation of narrow channels based on fluctuating is established.The experimental results show that the present model can be used to predict the heat flux of ONB in narrow rectangle channels.Features of ONB in natural circulation narrow rectangle channels are as follows:heating power is the incentive of the happen of ONB;the higher the heating power is,the higher the degree of superheat is,and the earlier the ONB will appear.With the pressurizing,the appearance of ONB will be delayed.The higher the degree of supercooling is,the later the ONB appears.The ONB will happen easier when there are noncondensable gases and roughness in the channels.
