An ultra-low emissions combustor,namely low emission stirred swirl(LESS)combustor was studied,based on a scheme of internally-staged/lean premixed and prevaporized(LPP)combustion.The LESS combustor consists of central...An ultra-low emissions combustor,namely low emission stirred swirl(LESS)combustor was studied,based on a scheme of internally-staged/lean premixed and prevaporized(LPP)combustion.The LESS combustor consists of central pilot stage and outer surrounded coaxially main stage,between which there exists aphysical isolation,namely the step height.The existence of step height delayed the pilot and main jets mixing.Experimental and numerical studies were carried out to investigate the influence of the step height on the combustion performance.A single dome rectangular combustor was utilized to conduct the lean lightoff and blowout experiments,and pollutant emission experiments.The experimental results showed that with the increase of step height by 38%,the lean lightoff and blowout fuel air ratio decreased by 57.4% and 37.5%,the NOx emission increased by 35.1%,and the combustion efficiency increased by 1.78%;while the CO,unburned hydrocarbons(UHC)emissions decreased.Furthermore,the total pressure loss was kept nearly constant.Non-reacting and reacting flow fields were numerically investigated to analyze the coupled characteristics of pilot and main jets with different step heights.A comparison of flow characteristics,spray structure,and combustion component as well as temperature field with different step heights was conducted.The numerical results showed that the increase of the step height shifted the peak velocity outwards.The enlargement of the primary recirculation zone(PRZ)resulted in the increase of the combustion efficiency and NOx emission,while the CO,UHC emissions decreeased.展开更多
通过大田小区试验,设置8个不同生育期灌水处理:各生育期都灌水(CK)、苗期不灌水(I1)、拔节期不灌水(I2)、抽穗期不灌水(I3)、灌浆成熟期不灌水(I4)、苗期+抽穗期不灌水(I13)、苗期+灌浆期不灌水(I14)、拔节期+灌浆期不灌水(I24)和4个氮...通过大田小区试验,设置8个不同生育期灌水处理:各生育期都灌水(CK)、苗期不灌水(I1)、拔节期不灌水(I2)、抽穗期不灌水(I3)、灌浆成熟期不灌水(I4)、苗期+抽穗期不灌水(I13)、苗期+灌浆期不灌水(I14)、拔节期+灌浆期不灌水(I24)和4个氮肥水平:不施氮(ZN)、低氮(LN,60 kg N/hm2)、中氮(MN,120 kg N/hm2)和高氮(HN,180 kg N/hm2),研究了不同生育期灌水和施氮对春玉米生长、产量及水分利用效率(WUE)的影响。结果表明,任何一个生育期不灌水都降低春玉米的株高、叶面积、籽粒产量;灌水对苗期株高影响不显著,氮肥对各生育期株高影响均显著,水氮互作效应对苗期株高影响不显著;与处理CK相比较,处理I2和处理I24对株高的影响最大,最高降低了11.42%;灌水,氮肥和水氮互作效应对各生育期叶面积均有显著影响,但两生育期不灌水处理大于单生育期不灌水处理对叶面积的影响;而单生育期不灌水处理对叶面积的影响平均来说为灌水处理I4>I3>I1>I2,两生育期不灌水处理在施氮水平ZN、LN下I13>I14>I24,而在施氮水平MN、HN下处理I14与处理I24差异不显著,却都大于处理I13;灌水和氮素效应对玉米的千粒重、穗粒重、籽粒产量都有显著的影响;与处理CK相比较,处理I3和处理I13对籽粒产量的影响最大,最大降幅为28.76%;I1和I4高氮处理具有较高的产量和水分利用效率。展开更多
文摘An ultra-low emissions combustor,namely low emission stirred swirl(LESS)combustor was studied,based on a scheme of internally-staged/lean premixed and prevaporized(LPP)combustion.The LESS combustor consists of central pilot stage and outer surrounded coaxially main stage,between which there exists aphysical isolation,namely the step height.The existence of step height delayed the pilot and main jets mixing.Experimental and numerical studies were carried out to investigate the influence of the step height on the combustion performance.A single dome rectangular combustor was utilized to conduct the lean lightoff and blowout experiments,and pollutant emission experiments.The experimental results showed that with the increase of step height by 38%,the lean lightoff and blowout fuel air ratio decreased by 57.4% and 37.5%,the NOx emission increased by 35.1%,and the combustion efficiency increased by 1.78%;while the CO,unburned hydrocarbons(UHC)emissions decreased.Furthermore,the total pressure loss was kept nearly constant.Non-reacting and reacting flow fields were numerically investigated to analyze the coupled characteristics of pilot and main jets with different step heights.A comparison of flow characteristics,spray structure,and combustion component as well as temperature field with different step heights was conducted.The numerical results showed that the increase of the step height shifted the peak velocity outwards.The enlargement of the primary recirculation zone(PRZ)resulted in the increase of the combustion efficiency and NOx emission,while the CO,UHC emissions decreeased.
文摘通过大田小区试验,设置8个不同生育期灌水处理:各生育期都灌水(CK)、苗期不灌水(I1)、拔节期不灌水(I2)、抽穗期不灌水(I3)、灌浆成熟期不灌水(I4)、苗期+抽穗期不灌水(I13)、苗期+灌浆期不灌水(I14)、拔节期+灌浆期不灌水(I24)和4个氮肥水平:不施氮(ZN)、低氮(LN,60 kg N/hm2)、中氮(MN,120 kg N/hm2)和高氮(HN,180 kg N/hm2),研究了不同生育期灌水和施氮对春玉米生长、产量及水分利用效率(WUE)的影响。结果表明,任何一个生育期不灌水都降低春玉米的株高、叶面积、籽粒产量;灌水对苗期株高影响不显著,氮肥对各生育期株高影响均显著,水氮互作效应对苗期株高影响不显著;与处理CK相比较,处理I2和处理I24对株高的影响最大,最高降低了11.42%;灌水,氮肥和水氮互作效应对各生育期叶面积均有显著影响,但两生育期不灌水处理大于单生育期不灌水处理对叶面积的影响;而单生育期不灌水处理对叶面积的影响平均来说为灌水处理I4>I3>I1>I2,两生育期不灌水处理在施氮水平ZN、LN下I13>I14>I24,而在施氮水平MN、HN下处理I14与处理I24差异不显著,却都大于处理I13;灌水和氮素效应对玉米的千粒重、穗粒重、籽粒产量都有显著的影响;与处理CK相比较,处理I3和处理I13对籽粒产量的影响最大,最大降幅为28.76%;I1和I4高氮处理具有较高的产量和水分利用效率。
