Lateral-intake multiple forebays are widely used in urban pumping stations,but there is still insufficient understanding of their hydraulic characteristics,making it difficult to provide scientifically based guidance ...Lateral-intake multiple forebays are widely used in urban pumping stations,but there is still insufficient understanding of their hydraulic characteristics,making it difficult to provide scientifically based guidance for determining optimal start-up combinations,which are critical to pumping station efficiency.This study numerically investigated the hydraulic characteristics of lateral-intake multiple forebays under different start-up combinations and,for the first time,applied entropy production theory to analyze the causes and locations of hydraulic loss.The lateral-intake causes undesired flow patterns,including helical mainstream and flow recirculation in the forebays,and mainstream one-sided concentration and backflow in the sumps.These undesired flow patterns become more significant with reduced standby pumps and increased inflow Froude numbers,directly degrading flow uniformity and increasing total hydraulic loss.Keeping the downstream pumps in operation for one-pump and two-pump standby conditions helps to improve forebay flow uniformity and reduce total hydraulic loss.Entropy production method revealed that turbulence dissipation is the main cause of total hydraulic loss in the forebays,accounting for over 90%,which is induced by helical mainstream and flow recirculation and impingement,occurring near the forebay inlets,sump piers and suction pipe mouths.By comprehensively evaluating flow patterns,uniformity,and hydraulic loss,the optimal start-up combination for different standby pump requirements was concluded as operating the downstream pumps while keeping the upstream pumps on standby.This provides a theoretical basis for investigating hydraulic characteristics and optimizing pump operation in urban pumping station forebays.展开更多
We demonstrate the generation of supercontinuum (SC) of over 1350 nm by injecting 790-nm, 15-fs, 74-MHz optical pulses into a 183-mm-long microstructured fiber with combination core and random cladding. The maximum to...We demonstrate the generation of supercontinuum (SC) of over 1350 nm by injecting 790-nm, 15-fs, 74-MHz optical pulses into a 183-mm-long microstructured fiber with combination core and random cladding. The maximum total power of SC is 73 mW with 290-mW pump power from 40x microscope objective. The wavelength and power ranging in SC as well as the polarization states and waveguide modes of the visible light can be tuned by adjusting the input end of MF.In particular, white light has been observed. To our knowledge, this is the first report of tunable properties in SC generation process using microstructured fiber with combination core and random cladding.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant No.52279063)supported by the Xizang Agricultural and Animal Husbandry University 2023 Talent Flexible Introduction Project(Grant No.755550014)+3 种基金the Jiangsu Province Natural Science Foundation(Grant No.BK20231462)the Fundamental Research Funds for the Central Universities(Grant No.B240201065,B240201055)the Jiangsu Innovation Support Programme for International Science and Technology Cooperation(Grant No.BZ2023047)Xizang Agriculture and Animal Husbandry College 2023 Talent Flexible Introduction Project(Grant No.755550014).
文摘Lateral-intake multiple forebays are widely used in urban pumping stations,but there is still insufficient understanding of their hydraulic characteristics,making it difficult to provide scientifically based guidance for determining optimal start-up combinations,which are critical to pumping station efficiency.This study numerically investigated the hydraulic characteristics of lateral-intake multiple forebays under different start-up combinations and,for the first time,applied entropy production theory to analyze the causes and locations of hydraulic loss.The lateral-intake causes undesired flow patterns,including helical mainstream and flow recirculation in the forebays,and mainstream one-sided concentration and backflow in the sumps.These undesired flow patterns become more significant with reduced standby pumps and increased inflow Froude numbers,directly degrading flow uniformity and increasing total hydraulic loss.Keeping the downstream pumps in operation for one-pump and two-pump standby conditions helps to improve forebay flow uniformity and reduce total hydraulic loss.Entropy production method revealed that turbulence dissipation is the main cause of total hydraulic loss in the forebays,accounting for over 90%,which is induced by helical mainstream and flow recirculation and impingement,occurring near the forebay inlets,sump piers and suction pipe mouths.By comprehensively evaluating flow patterns,uniformity,and hydraulic loss,the optimal start-up combination for different standby pump requirements was concluded as operating the downstream pumps while keeping the upstream pumps on standby.This provides a theoretical basis for investigating hydraulic characteristics and optimizing pump operation in urban pumping station forebays.
基金This work was supPorted by the Henan Cultivatlon Project for University Innovatlon Thlents.
文摘We demonstrate the generation of supercontinuum (SC) of over 1350 nm by injecting 790-nm, 15-fs, 74-MHz optical pulses into a 183-mm-long microstructured fiber with combination core and random cladding. The maximum total power of SC is 73 mW with 290-mW pump power from 40x microscope objective. The wavelength and power ranging in SC as well as the polarization states and waveguide modes of the visible light can be tuned by adjusting the input end of MF.In particular, white light has been observed. To our knowledge, this is the first report of tunable properties in SC generation process using microstructured fiber with combination core and random cladding.
