In nuclear reactors,temperature fluctuations of fluids may cause fatigue damage to adjacent structures;this is referred to as thermal striping.Research on thermal striping in the upper plenum has mainly focused on flu...In nuclear reactors,temperature fluctuations of fluids may cause fatigue damage to adjacent structures;this is referred to as thermal striping.Research on thermal striping in the upper plenum has mainly focused on fluid fields.Few experimental studies have been reported on solid structures in a fluid field with a coaxial jet.This study entailed an experimental study of the temperature fluctuations in the fluid and on a plate surface caused by a coaxial jet.The temperature fluctuations of the fluid and plate surfaces located at different heights were analyzed.The cause of the temperature fluctuation was analyzed using a transient temperature distribution.The results show that the mixing of the hot and cold fluids gradually becomes uniform in the positive axial direction.The average surface temperatures tended to be consistent.When the jet reaches the plate surface,the swing of the jet center,contraction and expansion of the cold jet,and changes in the jet shape result in temperature fluctuations.The intensity of the temperature fluctuation was affected by the position.More attention should be paid when the plate is located at a lower height,and between the hot and cold-fluid nozzles.展开更多
The particle dispersion characteristics of the dense gas-solids two-phase coaxial jets were investigated with high-speed camera.The results showed that with increasing gas velocity,three particle dispersion modes were...The particle dispersion characteristics of the dense gas-solids two-phase coaxial jets were investigated with high-speed camera.The results showed that with increasing gas velocity,three particle dispersion modes were observed:shear dispersion,wave dispersion and oscillating dispersion,after the particle flow passed through the intact length.The normalized intact length decreased with increasing gas velocity.For the wave dispersion,the unstable wavelength increased linearly with axial distance at different gas velocities.For the oscillating dispersion,oscillating frequency decreased at first and then increased with increasing gas velocity,so the oscillating frequency had a minimum when the gas velocity was about 65 m·s-1.展开更多
基金supported by the National Natural Science Foundation of China (No. 52075173)the Overseas Expertise Introduction Project for Discipline Innovation (No. B13020)
文摘In nuclear reactors,temperature fluctuations of fluids may cause fatigue damage to adjacent structures;this is referred to as thermal striping.Research on thermal striping in the upper plenum has mainly focused on fluid fields.Few experimental studies have been reported on solid structures in a fluid field with a coaxial jet.This study entailed an experimental study of the temperature fluctuations in the fluid and on a plate surface caused by a coaxial jet.The temperature fluctuations of the fluid and plate surfaces located at different heights were analyzed.The cause of the temperature fluctuation was analyzed using a transient temperature distribution.The results show that the mixing of the hot and cold fluids gradually becomes uniform in the positive axial direction.The average surface temperatures tended to be consistent.When the jet reaches the plate surface,the swing of the jet center,contraction and expansion of the cold jet,and changes in the jet shape result in temperature fluctuations.The intensity of the temperature fluctuation was affected by the position.More attention should be paid when the plate is located at a lower height,and between the hot and cold-fluid nozzles.
文摘The particle dispersion characteristics of the dense gas-solids two-phase coaxial jets were investigated with high-speed camera.The results showed that with increasing gas velocity,three particle dispersion modes were observed:shear dispersion,wave dispersion and oscillating dispersion,after the particle flow passed through the intact length.The normalized intact length decreased with increasing gas velocity.For the wave dispersion,the unstable wavelength increased linearly with axial distance at different gas velocities.For the oscillating dispersion,oscillating frequency decreased at first and then increased with increasing gas velocity,so the oscillating frequency had a minimum when the gas velocity was about 65 m·s-1.
