The formation of ice on the leading edge of aircraft engines is a serious issue,as it can have catastrophic consequences.The Swirl Anti-Icing(SAI)system,driven by ejection,circulates hot fluid within a 360°annula...The formation of ice on the leading edge of aircraft engines is a serious issue,as it can have catastrophic consequences.The Swirl Anti-Icing(SAI)system,driven by ejection,circulates hot fluid within a 360°annular chamber to heat the engine inlet lip surface and prevent icing.This study employs a validated Computational Fluid Dynamics(CFD)approach to study the impact of key geometric parameters of this system on flow and heat transfer characteristics within the anti-icing chamber.Additionally,the entropy generation rate and exergy efficiency are analyzed to assess the energy utilization in the system.The research findings indicate that,within the considered flow range,reducing the nozzle specific areaφfrom 0.03061 to 0.01083 can enhance the ejection coefficient by over 60.7%.This enhancement increases the air circulating rate,thereby intensifying convective heat transfer within the SAI chamber.However,the reduction inφalso leads to a significant increase in the required bleed air pressure and a higher entropy generation rate,indicating lower exergy efficiency.The nozzle angleθnotably affects the distribution of hot and cold spots on the lip surface of the SAI chamber.Increasingθfrom 0°to 20°reduces the maximum temperature difference on the anti-icing chamber surface by 60 K.展开更多
China’s Northwest Arid Region(NAR),with dry and cold climate conditions and glaciers widely developed in the high mountains,provides vital water resources for Asia.The consecutive cold,warm,dry and wet days have much...China’s Northwest Arid Region(NAR),with dry and cold climate conditions and glaciers widely developed in the high mountains,provides vital water resources for Asia.The consecutive cold,warm,dry and wet days have much higher impacts on the water cycle process in this region than extreme temperature and precipitation events with short durations but high intensities.Parametric and nonparametric trend analysis methods widely used in climatology and hydrology are employed to identify the temporal and spatial features of the changes in the consecutive cold,warm,dry and wet days in the NAR based on China’s 0.5°×0.5°meteorological grid datasets of daily temperature and precipitation from 1961 to 2018.This study found that(1)the consecutive cold days(Cold Spell Duration Indicator,CSDI),and the consecutive dry days(CDD)decreased,while the consecutive warm days(Warm Spell Duration Indicator,WSDI),and the consecutive wet days(CWD)increased from 1961 to 2018,(2)and the eastern Kunlun Mountains were the hot spots where all of these consecutive climate indices changed significantly,(3)and the changes in these consecutive climate indices were highly correlated with the rise in the Global Mean Land/Ocean Temperature Index.The results indicated that winters tended to warmer and dryer and summer became hotter and wetter during 1961–2018 in the NAR under the global warming,which can lead to the sustained glacier retreat and the increase in summer runoff in this region,and the eastern Kunlun Mountains are the area where could face high risks of water scarcity and floods if the changes in these climate indices continue in the future.Given the vulnerability of the socio-economic systems in the NAR to a water shortage and floods,it is most crucial to improve the strategies of water resources management,disaster prevention and risk management for this region under climate change.展开更多
The scarcity of water resources caused by the unique topography and uneven rainfall distribution in Hainan Island has become a major factor restricting local development. In order to provide effective and scientific r...The scarcity of water resources caused by the unique topography and uneven rainfall distribution in Hainan Island has become a major factor restricting local development. In order to provide effective and scientific reference basis for the overall water resource utilization status and solving this problem, this study calculated the water resource utilization situation of Hainan Island from 2017 to 2021 in detail using methods including water resource ecological footprint analysis. Furthermore, a spatial correlation analysis was conducted to examine the island's water resource utilization characteristics, and the driving factors behind the changes in water resource utilization over the past five years were analyzed using the LMDI model. The results show that:(1) During the study period, the water resource ecological footprint in Hainan Island exhibited a slow growth trend, while the ecological carrying capacity showed a downward tendency.The per capita ecological deficit of water resources remains relatively high, and the water consumption per 10 000 yuan GDP in the whole land continues to decrease, indicating that the overall pressure on water resource demand remains high with significant regional differences accompanied by the efficiency of water resource utilization steadily improving at the same time;(2) Agricultural water use accounts for the highest proportion in the entire water use structure, while ecological water use represents the smallest share, with a year-on-year increase, indicating that Hainan Island highlights the agricultural development and is increasingly conscious of the ecological environment;(3) Significant spatial differentiation in water resource utilization characteristics exists in Hainan Island, with the western region being a hot spot aggregation area for per capita water resource ecological footprint, per capita ecological carrying capacity of water resources, water consumption per 10 000 yuan GDP, while it is a cold spot cluster area for per capita ecological deficit of water resources. The opposite holds true for the eastern region of Hainan Island;(4) Economic and technological factors have a major impact on the changes in water resource ecological footprint within the designated area. Among them, economic factors drive the growth of the water resource ecological footprint in Hainan Island, and exacerbate local water resource consumption, while technological factors negatively contribute to the amount of water resource utilization in Hainan Island, indicating that advanced technology has improved water resource utilization efficiency and significantly reduced water resource consumption.展开更多
基金Shenyang Key Laboratory of Aircraft Icing and Ice Protection,Grant Number XFX20220303Education Department of Hunan Province,China,Grant Number 23A0504National Natural Science Foundation of China,Grant Number 52275108.
文摘The formation of ice on the leading edge of aircraft engines is a serious issue,as it can have catastrophic consequences.The Swirl Anti-Icing(SAI)system,driven by ejection,circulates hot fluid within a 360°annular chamber to heat the engine inlet lip surface and prevent icing.This study employs a validated Computational Fluid Dynamics(CFD)approach to study the impact of key geometric parameters of this system on flow and heat transfer characteristics within the anti-icing chamber.Additionally,the entropy generation rate and exergy efficiency are analyzed to assess the energy utilization in the system.The research findings indicate that,within the considered flow range,reducing the nozzle specific areaφfrom 0.03061 to 0.01083 can enhance the ejection coefficient by over 60.7%.This enhancement increases the air circulating rate,thereby intensifying convective heat transfer within the SAI chamber.However,the reduction inφalso leads to a significant increase in the required bleed air pressure and a higher entropy generation rate,indicating lower exergy efficiency.The nozzle angleθnotably affects the distribution of hot and cold spots on the lip surface of the SAI chamber.Increasingθfrom 0°to 20°reduces the maximum temperature difference on the anti-icing chamber surface by 60 K.
基金the Ministry of Science and Technology(Grant No.2018FY100502)the Young Talent Growth Fund Project of Northwest Institute of Ecological Environment and Resources,Chinese Academy of Sciences(Grant No.FEYS2019016)+2 种基金the National Natural Science Foundation of China(Grant No.41171378)the“Western Light”program of the Chinese Academy of Science(Grant No.2017-XBQNXZ-B-016)the Youth Innovation Promotion Association of the Chinese Academy of Sciences(Grant No.2019430)。
文摘China’s Northwest Arid Region(NAR),with dry and cold climate conditions and glaciers widely developed in the high mountains,provides vital water resources for Asia.The consecutive cold,warm,dry and wet days have much higher impacts on the water cycle process in this region than extreme temperature and precipitation events with short durations but high intensities.Parametric and nonparametric trend analysis methods widely used in climatology and hydrology are employed to identify the temporal and spatial features of the changes in the consecutive cold,warm,dry and wet days in the NAR based on China’s 0.5°×0.5°meteorological grid datasets of daily temperature and precipitation from 1961 to 2018.This study found that(1)the consecutive cold days(Cold Spell Duration Indicator,CSDI),and the consecutive dry days(CDD)decreased,while the consecutive warm days(Warm Spell Duration Indicator,WSDI),and the consecutive wet days(CWD)increased from 1961 to 2018,(2)and the eastern Kunlun Mountains were the hot spots where all of these consecutive climate indices changed significantly,(3)and the changes in these consecutive climate indices were highly correlated with the rise in the Global Mean Land/Ocean Temperature Index.The results indicated that winters tended to warmer and dryer and summer became hotter and wetter during 1961–2018 in the NAR under the global warming,which can lead to the sustained glacier retreat and the increase in summer runoff in this region,and the eastern Kunlun Mountains are the area where could face high risks of water scarcity and floods if the changes in these climate indices continue in the future.Given the vulnerability of the socio-economic systems in the NAR to a water shortage and floods,it is most crucial to improve the strategies of water resources management,disaster prevention and risk management for this region under climate change.
基金funded by Guangxi Karst Science and Technology Innovation Fund (KFKT2022001)China Geological Survey Program (DD20230416)。
文摘The scarcity of water resources caused by the unique topography and uneven rainfall distribution in Hainan Island has become a major factor restricting local development. In order to provide effective and scientific reference basis for the overall water resource utilization status and solving this problem, this study calculated the water resource utilization situation of Hainan Island from 2017 to 2021 in detail using methods including water resource ecological footprint analysis. Furthermore, a spatial correlation analysis was conducted to examine the island's water resource utilization characteristics, and the driving factors behind the changes in water resource utilization over the past five years were analyzed using the LMDI model. The results show that:(1) During the study period, the water resource ecological footprint in Hainan Island exhibited a slow growth trend, while the ecological carrying capacity showed a downward tendency.The per capita ecological deficit of water resources remains relatively high, and the water consumption per 10 000 yuan GDP in the whole land continues to decrease, indicating that the overall pressure on water resource demand remains high with significant regional differences accompanied by the efficiency of water resource utilization steadily improving at the same time;(2) Agricultural water use accounts for the highest proportion in the entire water use structure, while ecological water use represents the smallest share, with a year-on-year increase, indicating that Hainan Island highlights the agricultural development and is increasingly conscious of the ecological environment;(3) Significant spatial differentiation in water resource utilization characteristics exists in Hainan Island, with the western region being a hot spot aggregation area for per capita water resource ecological footprint, per capita ecological carrying capacity of water resources, water consumption per 10 000 yuan GDP, while it is a cold spot cluster area for per capita ecological deficit of water resources. The opposite holds true for the eastern region of Hainan Island;(4) Economic and technological factors have a major impact on the changes in water resource ecological footprint within the designated area. Among them, economic factors drive the growth of the water resource ecological footprint in Hainan Island, and exacerbate local water resource consumption, while technological factors negatively contribute to the amount of water resource utilization in Hainan Island, indicating that advanced technology has improved water resource utilization efficiency and significantly reduced water resource consumption.
