An investigation on the ventral diverterless high offset S-shaped inlet is carried out at Mach numbers from 0.600 to 1.534, angles of attack from -4° to 9.4°, and yaw angles from 0° to 8°. Results ...An investigation on the ventral diverterless high offset S-shaped inlet is carried out at Mach numbers from 0.600 to 1.534, angles of attack from -4° to 9.4°, and yaw angles from 0° to 8°. Results indicate： （1） a large region of low total pressure exists at the lower part of the inlet exit caused by the counter-rotating vortices in the S-shaped duct; （2） the performances of the inlet at Mach number 1.000 reach almost the highest, so the propulsion system could work efficiently in terms of aerodynamics; （3） the total pressure recovery increases slowly at first and then remains unvaried as the Mach number rises from 0.6 to 1.0, however, it does in an opposite manner in the conventional diverter-equipped S-shaped inlet; （4） the performances of the inlet are generally insensitive to angles of attack from -4° to 9.4° and yaw angles from 0° to 8° at Mach number 0.850, and angles of attack from -2° to 6° and yaw angles from 0° to 5° at Mach number 1.534.展开更多
A 17-year-old adolescent with non-operated double inlet left-ventricle and severe stenosed parachute mitral valve is reported. He was admitted with repetitive syncope related to intermittent atrial fibrillation. Life-...A 17-year-old adolescent with non-operated double inlet left-ventricle and severe stenosed parachute mitral valve is reported. He was admitted with repetitive syncope related to intermittent atrial fibrillation. Life-threatening syncope combined with pre- and post-capillary pulmonary hypertension together with his single ventricle pathophysiology led to the decision for left atrial decompression by percutaneous static atrial septum ballooning after transseptal needle perforation. Aiming to create a restrictive atrial septum defect, unloading of the left atrium without disturbing the balanced hemodynamics was directed for a long-term palliation or as a basis for a further surgical follow-up approach.展开更多
In response to the divergent understanding of double inlet cyclone performance in the literature,the effect of inlet volute wrap angle on the performance and flow field of double inlet cyclone separator was studied by...In response to the divergent understanding of double inlet cyclone performance in the literature,the effect of inlet volute wrap angle on the performance and flow field of double inlet cyclone separator was studied by Computational Fluid Dynamic(CFD)method.The results showed that the inlet volute wrap angle can affect the comparison results of the single and double inlet gas cyclones with the same total inlet cross-sectional area and velocity.0°and 90°volute double inlet improved the efficiency mainly by separating particles below 10μm,while 180°volute double inlet had no separation advantage for any particles,so the symmetrical double inlet does not always improve the efficiency,and the appropriate inlet volute wrap angle should be selected according to the actual situation,otherwise,the expected performance requirements of the symmetrical double inlet cyclone cannot be achieved.Compared with the flow field,it is found that the inlet volute wrap angle changed the tangential velocity of the sym-metrical double inlet cyclone separator,thus changing the performance.展开更多
The inlet recirculation characteristics of double suction centrifugal compressor with unsymmetrical inlet structures were studied in numerical method,mainly focused on three issues including the amounts and difference...The inlet recirculation characteristics of double suction centrifugal compressor with unsymmetrical inlet structures were studied in numerical method,mainly focused on three issues including the amounts and differences of the inlet recirculation in different working conditions,the circumferential non-uniform distributions of the inlet recirculation,the recirculation velocity distributions of the upstream slot of the rear impeller.The results show that there are some differences between the recirculation of the front impeller and that of the rear impeller in whole working conditions..In design speed,the recirculation flow rate of the rear impeller is larger than that of the front impeller in the large flow range,but in the small flow range,the recirculation flow rate of the rear impeller is smaller than that of the front impeller.In different working conditions,the recirculation velocity distributions of the front and rear impeller are non-uniform along the circumferential direction and their non-uniform extents are quite different.The circumferential non-uniform extent of the recirculation velocity varies with the working conditions change.The circumferential non-uniform extent of the recirculation velocity of front impeller and its distribution are determined by the static pressure distribution of the front impeller,but that of the rear impeller is decided by the coupling effects of the inlet flow distortion of the rear impeller,the circumferential unsymmetrical distribution of the upstream slot and the asymmetric structure of the volute.In the design flow and small flow conditions,the recirculation velocities at different circumferential positions of the mean line of the upstream slot cross-section of the rear impeller are quite different,and the recirculation velocities distribution forms at both sides of the mean line are different.The recirculation velocity distributions in the cross-section of the upstream slot depend on the static pressure distributions in the intake duct.展开更多
基金National Basic Research Program of China (5130802)
文摘An investigation on the ventral diverterless high offset S-shaped inlet is carried out at Mach numbers from 0.600 to 1.534, angles of attack from -4° to 9.4°, and yaw angles from 0° to 8°. Results indicate： （1） a large region of low total pressure exists at the lower part of the inlet exit caused by the counter-rotating vortices in the S-shaped duct; （2） the performances of the inlet at Mach number 1.000 reach almost the highest, so the propulsion system could work efficiently in terms of aerodynamics; （3） the total pressure recovery increases slowly at first and then remains unvaried as the Mach number rises from 0.6 to 1.0, however, it does in an opposite manner in the conventional diverter-equipped S-shaped inlet; （4） the performances of the inlet are generally insensitive to angles of attack from -4° to 9.4° and yaw angles from 0° to 8° at Mach number 0.850, and angles of attack from -2° to 6° and yaw angles from 0° to 5° at Mach number 1.534.
文摘A 17-year-old adolescent with non-operated double inlet left-ventricle and severe stenosed parachute mitral valve is reported. He was admitted with repetitive syncope related to intermittent atrial fibrillation. Life-threatening syncope combined with pre- and post-capillary pulmonary hypertension together with his single ventricle pathophysiology led to the decision for left atrial decompression by percutaneous static atrial septum ballooning after transseptal needle perforation. Aiming to create a restrictive atrial septum defect, unloading of the left atrium without disturbing the balanced hemodynamics was directed for a long-term palliation or as a basis for a further surgical follow-up approach.
基金supported by the National Natural Science Foundation of China(grant No.21978322,21276274).
文摘In response to the divergent understanding of double inlet cyclone performance in the literature,the effect of inlet volute wrap angle on the performance and flow field of double inlet cyclone separator was studied by Computational Fluid Dynamic(CFD)method.The results showed that the inlet volute wrap angle can affect the comparison results of the single and double inlet gas cyclones with the same total inlet cross-sectional area and velocity.0°and 90°volute double inlet improved the efficiency mainly by separating particles below 10μm,while 180°volute double inlet had no separation advantage for any particles,so the symmetrical double inlet does not always improve the efficiency,and the appropriate inlet volute wrap angle should be selected according to the actual situation,otherwise,the expected performance requirements of the symmetrical double inlet cyclone cannot be achieved.Compared with the flow field,it is found that the inlet volute wrap angle changed the tangential velocity of the sym-metrical double inlet cyclone separator,thus changing the performance.
基金funded by the National Natural Science Foundation of China(No.51276017)the Specialized Research Fund for the Doctoral Program of Higher Education(No.20131101110015),China
文摘The inlet recirculation characteristics of double suction centrifugal compressor with unsymmetrical inlet structures were studied in numerical method,mainly focused on three issues including the amounts and differences of the inlet recirculation in different working conditions,the circumferential non-uniform distributions of the inlet recirculation,the recirculation velocity distributions of the upstream slot of the rear impeller.The results show that there are some differences between the recirculation of the front impeller and that of the rear impeller in whole working conditions..In design speed,the recirculation flow rate of the rear impeller is larger than that of the front impeller in the large flow range,but in the small flow range,the recirculation flow rate of the rear impeller is smaller than that of the front impeller.In different working conditions,the recirculation velocity distributions of the front and rear impeller are non-uniform along the circumferential direction and their non-uniform extents are quite different.The circumferential non-uniform extent of the recirculation velocity varies with the working conditions change.The circumferential non-uniform extent of the recirculation velocity of front impeller and its distribution are determined by the static pressure distribution of the front impeller,but that of the rear impeller is decided by the coupling effects of the inlet flow distortion of the rear impeller,the circumferential unsymmetrical distribution of the upstream slot and the asymmetric structure of the volute.In the design flow and small flow conditions,the recirculation velocities at different circumferential positions of the mean line of the upstream slot cross-section of the rear impeller are quite different,and the recirculation velocities distribution forms at both sides of the mean line are different.The recirculation velocity distributions in the cross-section of the upstream slot depend on the static pressure distributions in the intake duct.
