Although buoyancy and cracking reactions are strongly coupled in the active cooling process, most of the previous studies consider only one of these factors, and their coupling relationship has not been considerably e...Although buoyancy and cracking reactions are strongly coupled in the active cooling process, most of the previous studies consider only one of these factors, and their coupling relationship has not been considerably examined. In this work, this coupling relationship was numerically investigated with complete consideration of different cases of heating, and in the view of energy transport and conversion. By comparing with the no-gravity case(NGC), the results indicate that buoyancy has a significant effect on the bottom-heated case(BHC) and side-heated case(SHC), but has little influence on the top-heated case(THC) owing to the different magnitudes of secondary flow. The heat transfer of the BHC and SHC was significantly enhanced by the secondary flow, but their energy conversion was simultaneously impaired.The conversion of the BHC and SHC was approximately half that of the THC and NGC. For all cases, by analyzing the energy transport ways, the cross section can be classified into three regions in the heating direction. Laminar conduction dominates in region Ⅰ, but gradually fails in region Ⅱ, where its role is replaced by other energy transport ways. In region Ⅲ, convection dominates the energy transport for BHC and SHC, whereas turbulence dominates for THC and NGC.展开更多
Large Eddy Simulation(LES)has been employed for the investigation of supersonic flow characteristics in five ducts with varying cross-sectional geometries.The numerical results reveal that flow channel configurations ...Large Eddy Simulation(LES)has been employed for the investigation of supersonic flow characteristics in five ducts with varying cross-sectional geometries.The numerical results reveal that flow channel configurations exert a considerable influence on the mainstream flow and the near-wall flow behavior.In contrast to straight ducts,square-to-circular and rectangular-to-circular ducts exhibit thicker boundary layers and a greater presence of vortex structures.Given the same inlet area,rectangular-to-circular ducts lead to higher flow drag force and total pressure loss than square-to-circular ducts.Characterized by the substantial flow separation and shock waves,the"S-shaped duct shows significant vertically-asymmetric characteristics.展开更多
基金supported by the Scientific Research Start-up Funds for Introducing Talent at Sichuan University (20822041C4013)。
文摘Although buoyancy and cracking reactions are strongly coupled in the active cooling process, most of the previous studies consider only one of these factors, and their coupling relationship has not been considerably examined. In this work, this coupling relationship was numerically investigated with complete consideration of different cases of heating, and in the view of energy transport and conversion. By comparing with the no-gravity case(NGC), the results indicate that buoyancy has a significant effect on the bottom-heated case(BHC) and side-heated case(SHC), but has little influence on the top-heated case(THC) owing to the different magnitudes of secondary flow. The heat transfer of the BHC and SHC was significantly enhanced by the secondary flow, but their energy conversion was simultaneously impaired.The conversion of the BHC and SHC was approximately half that of the THC and NGC. For all cases, by analyzing the energy transport ways, the cross section can be classified into three regions in the heating direction. Laminar conduction dominates in region Ⅰ, but gradually fails in region Ⅱ, where its role is replaced by other energy transport ways. In region Ⅲ, convection dominates the energy transport for BHC and SHC, whereas turbulence dominates for THC and NGC.
基金the National Natural Science Foundation of China(Grant Nos.92252206,12102471 and 11925207)。
文摘Large Eddy Simulation(LES)has been employed for the investigation of supersonic flow characteristics in five ducts with varying cross-sectional geometries.The numerical results reveal that flow channel configurations exert a considerable influence on the mainstream flow and the near-wall flow behavior.In contrast to straight ducts,square-to-circular and rectangular-to-circular ducts exhibit thicker boundary layers and a greater presence of vortex structures.Given the same inlet area,rectangular-to-circular ducts lead to higher flow drag force and total pressure loss than square-to-circular ducts.Characterized by the substantial flow separation and shock waves,the"S-shaped duct shows significant vertically-asymmetric characteristics.
