工频电磁场（power frequency electromagnetic field）是由输电线及家用电器所产生的一种极低频电磁场。我国和欧洲一些国家采用50Hz为工作频率，而西方一些国家（如美国、加拿大）使用60Hz。电磁场暴露与癌症的关系至今尚无定论。流...工频电磁场（power frequency electromagnetic field）是由输电线及家用电器所产生的一种极低频电磁场。我国和欧洲一些国家采用50Hz为工作频率，而西方一些国家（如美国、加拿大）使用60Hz。电磁场暴露与癌症的关系至今尚无定论。流行病学调查显示，工频电磁场暴露可导致儿童白血病发病率升高，据此，国际癌症研究机构（IARC）已于2001年将其列为“可疑致癌物质”。展开更多
Inlet distortion is one of the main factors for the degradation of aerodynamic performance and stability margin of the compressor in practical operation. Due to the change of the inlet shape and the large amount of in...Inlet distortion is one of the main factors for the degradation of aerodynamic performance and stability margin of the compressor in practical operation. Due to the change of the inlet shape and the large amount of inhalation of the body Boundary Layer, the ducted thrust fan of the Boundary Layer Ingestion (BLI) propulsion system inevitably works in the intake distortion condition. In this paper, the ducted thrust fan in a BLI propulsion system is taken as the research object. The influence of radial and circumferential total pressure distortion on the inlet section of the ducted thrust fan caused by boundary layer suction and inlet shape is studied by steady single channel and fullloop numerical simulation. The influence law of distortion intensity and distortion range of the two types of distortion patterns of the distortion map is analyzed emphatically. The results show that :(1) the greater the range and intensity of the radial total pressure distortion are, the more affected the performance of the ducted thrust fan is;(2) The aero-dynamic performance decline amplitude of the ducted thrust fan increases with the increase of the intensity of the circumferential total pressure distortion;The transmission law of the circumferential total pressure distortion intensity along the inlet and outlet of the fan is almost the same. Different working conditions have influence on the attenuation degree of the circumferential total pressure distortion in the ducted thrust fan, and the attenuation range of the circumferential total pressure distortion in the design working condition is the largest.展开更多
文摘工频电磁场（power frequency electromagnetic field）是由输电线及家用电器所产生的一种极低频电磁场。我国和欧洲一些国家采用50Hz为工作频率，而西方一些国家（如美国、加拿大）使用60Hz。电磁场暴露与癌症的关系至今尚无定论。流行病学调查显示，工频电磁场暴露可导致儿童白血病发病率升高，据此，国际癌症研究机构（IARC）已于2001年将其列为“可疑致癌物质”。
基金National Natural Science Foundation of China(No.51706183,No.51790512)。
文摘Inlet distortion is one of the main factors for the degradation of aerodynamic performance and stability margin of the compressor in practical operation. Due to the change of the inlet shape and the large amount of inhalation of the body Boundary Layer, the ducted thrust fan of the Boundary Layer Ingestion (BLI) propulsion system inevitably works in the intake distortion condition. In this paper, the ducted thrust fan in a BLI propulsion system is taken as the research object. The influence of radial and circumferential total pressure distortion on the inlet section of the ducted thrust fan caused by boundary layer suction and inlet shape is studied by steady single channel and fullloop numerical simulation. The influence law of distortion intensity and distortion range of the two types of distortion patterns of the distortion map is analyzed emphatically. The results show that :(1) the greater the range and intensity of the radial total pressure distortion are, the more affected the performance of the ducted thrust fan is;(2) The aero-dynamic performance decline amplitude of the ducted thrust fan increases with the increase of the intensity of the circumferential total pressure distortion;The transmission law of the circumferential total pressure distortion intensity along the inlet and outlet of the fan is almost the same. Different working conditions have influence on the attenuation degree of the circumferential total pressure distortion in the ducted thrust fan, and the attenuation range of the circumferential total pressure distortion in the design working condition is the largest.
