NH_(3)作为氢能载体,可实现氢能远距离输运。针对NH_(3)燃烧的反应性低、稳定性差、高燃料型NO_(x)排放问题,设计旋流燃烧器和空气分级燃烧室,实验研究功率为5~23 k W的NH_(3)、NH_(3)/CH_(4)扩散火焰NO_(x)排放特性。并采用化学反应器...NH_(3)作为氢能载体,可实现氢能远距离输运。针对NH_(3)燃烧的反应性低、稳定性差、高燃料型NO_(x)排放问题,设计旋流燃烧器和空气分级燃烧室,实验研究功率为5~23 k W的NH_(3)、NH_(3)/CH_(4)扩散火焰NO_(x)排放特性。并采用化学反应器网络(CRN)进行化学动力学模拟,分析排放变化的原因。结果表明:5 kW、Ф_(pri)=1.05的条件下,NH_(3)火焰NO_(x)测量排放最低为114.4×10^(-6)@15%O_(2);随着功率升高,NO_(x)排放增加,且导致燃烧不充分、火焰延长,此时最佳Ф_(pri)提前、燃烧范围减少、NO_(x)进一步增加;本文的CRN更适合模拟预混燃烧的NO_(x)排放,而不是扩散燃烧;功率升高不会改变反应路径,但生成NO的基元反应速率的升高幅度略大于消耗NO的基元反应速率,从而导致NO排放升高.展开更多
Based on high-resolution,Array for Real-time Geostrophic Oceanography(Argo)profiles and Sea Level Anomaly(SLA)data,this study statistically analyzes and compares turbulent diapycnal mixing profiles inside and outside ...Based on high-resolution,Array for Real-time Geostrophic Oceanography(Argo)profiles and Sea Level Anomaly(SLA)data,this study statistically analyzes and compares turbulent diapycnal mixing profiles inside and outside mesoscale eddies in the Gulf Stream region.The result indicates that average diapycnal diffusivity at 300–540 m depths in anticyclonic eddies reaches4.0×10-5 m2 s-1.This is significantly higher than the 1.6×10-5 m2 s-1 outside eddies and 0.8×10-5 m2 s-1 in cyclonic eddies.Probabilities of diapycnal diffusivity greater than 10-4 m2 s-1 within anticyclonic and cyclonic eddies and outside eddies are29%,5%and 12%,respectively.However,magnitudes of average diapycnal diffusivity at 540–900 m depths in these three cases are of the same order,10-5 m2 s-1.Twenty-four of a total 38 anticyclonic eddies had enhanced mixing in the ocean interior,and 22 were observed during or shortly after strong winds.The coincidence between enhanced mixing and strong wind stress indicates that more wind-induced,near-inertial wave energy propagates downward in anticyclonic eddies.The deeper part of 12 profiles(below 540 m)in anticyclonic eddies had vertical overturns with Thorpe scale exceeding 5 m,among which three profiles had overturns reaching 20 m.Enhanced mixing may have occurred in deep layers of some profiles,although it was not evident in average conditions.展开更多
A nuclear accident involving the leaking of radioactive pollutants occurred at the Fukushima Nuclear Power Plant in Japan, following an earthquake and subsequent tsunami on March 11,2011. Using official Japanese data ...A nuclear accident involving the leaking of radioactive pollutants occurred at the Fukushima Nuclear Power Plant in Japan, following an earthquake and subsequent tsunami on March 11,2011. Using official Japanese data on pollutant emissions during the accident, this study simulates the dispersion of nuclear pollutants. The source term of the nuclear leakage of radioactive material is designed using PM2.5 as the tracer of radioactive pollutants, and the study considers dry and wet deposition processes. A coupled-model system is constructed from the air-quality model Models-3/CMAQ and the Weather Research and Forecasting atmospheric model. The transport path and distribution of radioactive pollutants over long and short distances are simulated with different model horizontal resolutions of 30 and 4 km respectively. The long-distance simulation shows that, following the Fukushima nuclear accident, under the effect of westerly winds, radioactive pollutants are transported generally towards the eastern Pacific and reach the American continent after 5 days, but their concentration is only about 10-7 times the concentration near the Fukushima Nuclear Power Plant. The time required for pollutants to reach the United States is basically consistent with measurements made in California on March 18. Because the upper westerly wind is faster than the lower westerly wind, the distribution of pollutants tilts eastward in terms of its vertical structure. The short-distance （local） highresolution simulation indicates that strong winds and precipitation associated with a cyclone can accelerate the deposition, dif- fusion and transport of pollutions, and local cyclonic circulation can change the transport path of pollutants, even resulting in repeated effects of pollution in some areas. Pollutants disperse to southeastern Honshu, Japan, on March 14, 2011, agreeing well with the timing of local observations of increases in the absorbed dose rate. Results also show that radioactive pollutants from the Fukushima nuclear accident are mainly transported and diffuse eastward, resulting in a relatively short-term impact on the Japanese mainland even under the influence of the cyclone system. Therefore, in terms of atmospheric conditions, the location of the Fukusbima Nuclear Power Plant is appropriate and could serve as a reference to site selection and protection of other nuclear facilities.展开更多
In this paper, the design of plasma swirler is presented in detail. The experiments were carded out to verify the feasibility of using plasma swirler to control diffusion flame. The plasma swider consists of multiple ...In this paper, the design of plasma swirler is presented in detail. The experiments were carded out to verify the feasibility of using plasma swirler to control diffusion flame. The plasma swider consists of multiple electrodes with staggered arrangement on both sides of combustor＇s expansion section. The plasma swirler can enhance combustion stability through ionizing the air to produce active free radical and promoting the swirling air. In the experiments, the flame response to the plasma swider was examined with OH distribution by planar laser induced fluorescence （PLIF）. The experimental results showed that the flame reaction zone was broadened with the increase of the plasma exciting, and this demonstrated that the plasma swirler could be used to control diffusion flame. The design of plasma swirler is feasible.展开更多
文摘NH_(3)作为氢能载体,可实现氢能远距离输运。针对NH_(3)燃烧的反应性低、稳定性差、高燃料型NO_(x)排放问题,设计旋流燃烧器和空气分级燃烧室,实验研究功率为5~23 k W的NH_(3)、NH_(3)/CH_(4)扩散火焰NO_(x)排放特性。并采用化学反应器网络(CRN)进行化学动力学模拟,分析排放变化的原因。结果表明:5 kW、Ф_(pri)=1.05的条件下,NH_(3)火焰NO_(x)测量排放最低为114.4×10^(-6)@15%O_(2);随着功率升高,NO_(x)排放增加,且导致燃烧不充分、火焰延长,此时最佳Ф_(pri)提前、燃烧范围减少、NO_(x)进一步增加;本文的CRN更适合模拟预混燃烧的NO_(x)排放,而不是扩散燃烧;功率升高不会改变反应路径,但生成NO的基元反应速率的升高幅度略大于消耗NO的基元反应速率,从而导致NO排放升高.
基金supported by the National Natural Science Foundation of China(Grant Nos.41106012,41176008,91028008)a grant from Sanya Institute of Deep-Sea Science and Engineering(Grant No.SIDSSE-201207)
文摘Based on high-resolution,Array for Real-time Geostrophic Oceanography(Argo)profiles and Sea Level Anomaly(SLA)data,this study statistically analyzes and compares turbulent diapycnal mixing profiles inside and outside mesoscale eddies in the Gulf Stream region.The result indicates that average diapycnal diffusivity at 300–540 m depths in anticyclonic eddies reaches4.0×10-5 m2 s-1.This is significantly higher than the 1.6×10-5 m2 s-1 outside eddies and 0.8×10-5 m2 s-1 in cyclonic eddies.Probabilities of diapycnal diffusivity greater than 10-4 m2 s-1 within anticyclonic and cyclonic eddies and outside eddies are29%,5%and 12%,respectively.However,magnitudes of average diapycnal diffusivity at 540–900 m depths in these three cases are of the same order,10-5 m2 s-1.Twenty-four of a total 38 anticyclonic eddies had enhanced mixing in the ocean interior,and 22 were observed during or shortly after strong winds.The coincidence between enhanced mixing and strong wind stress indicates that more wind-induced,near-inertial wave energy propagates downward in anticyclonic eddies.The deeper part of 12 profiles(below 540 m)in anticyclonic eddies had vertical overturns with Thorpe scale exceeding 5 m,among which three profiles had overturns reaching 20 m.Enhanced mixing may have occurred in deep layers of some profiles,although it was not evident in average conditions.
基金supported by the Special Funds of Public Welfare of China (Grant No. GYHY201306061)the National Natural Science Foundation of China (Grant Nos. 41230421, 41105065 & 41275128)
文摘A nuclear accident involving the leaking of radioactive pollutants occurred at the Fukushima Nuclear Power Plant in Japan, following an earthquake and subsequent tsunami on March 11,2011. Using official Japanese data on pollutant emissions during the accident, this study simulates the dispersion of nuclear pollutants. The source term of the nuclear leakage of radioactive material is designed using PM2.5 as the tracer of radioactive pollutants, and the study considers dry and wet deposition processes. A coupled-model system is constructed from the air-quality model Models-3/CMAQ and the Weather Research and Forecasting atmospheric model. The transport path and distribution of radioactive pollutants over long and short distances are simulated with different model horizontal resolutions of 30 and 4 km respectively. The long-distance simulation shows that, following the Fukushima nuclear accident, under the effect of westerly winds, radioactive pollutants are transported generally towards the eastern Pacific and reach the American continent after 5 days, but their concentration is only about 10-7 times the concentration near the Fukushima Nuclear Power Plant. The time required for pollutants to reach the United States is basically consistent with measurements made in California on March 18. Because the upper westerly wind is faster than the lower westerly wind, the distribution of pollutants tilts eastward in terms of its vertical structure. The short-distance （local） highresolution simulation indicates that strong winds and precipitation associated with a cyclone can accelerate the deposition, dif- fusion and transport of pollutions, and local cyclonic circulation can change the transport path of pollutants, even resulting in repeated effects of pollution in some areas. Pollutants disperse to southeastern Honshu, Japan, on March 14, 2011, agreeing well with the timing of local observations of increases in the absorbed dose rate. Results also show that radioactive pollutants from the Fukushima nuclear accident are mainly transported and diffuse eastward, resulting in a relatively short-term impact on the Japanese mainland even under the influence of the cyclone system. Therefore, in terms of atmospheric conditions, the location of the Fukusbima Nuclear Power Plant is appropriate and could serve as a reference to site selection and protection of other nuclear facilities.
基金supported by the National Natural Science Foundation of China (Grant Nos. 51006104, 51076150 and 50906085)
文摘In this paper, the design of plasma swirler is presented in detail. The experiments were carded out to verify the feasibility of using plasma swirler to control diffusion flame. The plasma swider consists of multiple electrodes with staggered arrangement on both sides of combustor＇s expansion section. The plasma swirler can enhance combustion stability through ionizing the air to produce active free radical and promoting the swirling air. In the experiments, the flame response to the plasma swider was examined with OH distribution by planar laser induced fluorescence （PLIF）. The experimental results showed that the flame reaction zone was broadened with the increase of the plasma exciting, and this demonstrated that the plasma swirler could be used to control diffusion flame. The design of plasma swirler is feasible.
