The tropical cyclone motion is numerically simulated with a quasi-geostrophic baroclinic model. The flow field of a tropical cyclone is decomposed into its axisymmetric and asymmetric components. The relation between ...The tropical cyclone motion is numerically simulated with a quasi-geostrophic baroclinic model. The flow field of a tropical cyclone is decomposed into its axisymmetric and asymmetric components. The relation between the ventilation flow vector and the motion vector of the tropical cyclone is inves- tigated.The results of numerical experiments indicate:(1) There are both large-scale beta gyres and small-scale gyres in the asyrnmetric flow field.(2) The interaction between small-scale gyres and large-scale beta gyres leads to the oscillation of translation speed and translation direction for the tropi- cal cyclone.(3) There are the large deviations between the ventilation flow vector calculated by means of Fiorino and Elsberry's method and the motion vector of tropical cyclone.(4) The ventila- tion flow vector computed using the improved method closely correlates with the motion vector of the tropical cyclone.展开更多
This study applied the numerical simulator tool FDS （fire dynamics simulator）, Version 5.53, and focused on the simulation of the natural smoke flow ventilation design system, an innovative ventilation design using ...This study applied the numerical simulator tool FDS （fire dynamics simulator）, Version 5.53, and focused on the simulation of the natural smoke flow ventilation design system, an innovative ventilation design using the parallel processing technology MPI （message passing interface）. The design was then compared with the exhaust efficiency of a typical natural smoke vent. The natural smoke flow ventilation design system was located at the top of the factory, where smoke streams effectively converged. Therefore, the source of fire was designed to be 2 MW, which has a better exhaust efficiency than typical natural smoke vent with same area. The simulation discovered that the exhaust efficiency of the natural smoke ventilation design systems is higher than that of typical natural smoke vent with 2 times the opening area and that was not affected by external wind speed, Instead, external wind speed can help to enhance the exhaust efficiency. Smoke exhaust of typical natural smoke vents was affected by external wind speed, even leading them to become air inlets which would disturb the flow of air indoors, leading to smoke accumulation within the factory.展开更多
A new type fully reversible combined blade is presented, which can fully reverse airflow during the inverse ventilation by simply reversion. It is suitable for reversible axial flow fans used in tunnel and mine ventil...A new type fully reversible combined blade is presented, which can fully reverse airflow during the inverse ventilation by simply reversion. It is suitable for reversible axial flow fans used in tunnel and mine ventilation. The optimal parameters such as overlap ratio and pitch ratio are determined through cascade experiment. Experiment results also show a big promotion of maximum lift coefficient C1,max and stall attack angle a1,max compared to the existing bi-directional symmetry airfoils.展开更多
基金This work is supported by the 8th Five-Year Project of Key Item Research of China under Grant 85-906-07-02-04.
文摘The tropical cyclone motion is numerically simulated with a quasi-geostrophic baroclinic model. The flow field of a tropical cyclone is decomposed into its axisymmetric and asymmetric components. The relation between the ventilation flow vector and the motion vector of the tropical cyclone is inves- tigated.The results of numerical experiments indicate:(1) There are both large-scale beta gyres and small-scale gyres in the asyrnmetric flow field.(2) The interaction between small-scale gyres and large-scale beta gyres leads to the oscillation of translation speed and translation direction for the tropi- cal cyclone.(3) There are the large deviations between the ventilation flow vector calculated by means of Fiorino and Elsberry's method and the motion vector of tropical cyclone.(4) The ventila- tion flow vector computed using the improved method closely correlates with the motion vector of the tropical cyclone.
文摘This study applied the numerical simulator tool FDS （fire dynamics simulator）, Version 5.53, and focused on the simulation of the natural smoke flow ventilation design system, an innovative ventilation design using the parallel processing technology MPI （message passing interface）. The design was then compared with the exhaust efficiency of a typical natural smoke vent. The natural smoke flow ventilation design system was located at the top of the factory, where smoke streams effectively converged. Therefore, the source of fire was designed to be 2 MW, which has a better exhaust efficiency than typical natural smoke vent with same area. The simulation discovered that the exhaust efficiency of the natural smoke ventilation design systems is higher than that of typical natural smoke vent with 2 times the opening area and that was not affected by external wind speed, Instead, external wind speed can help to enhance the exhaust efficiency. Smoke exhaust of typical natural smoke vents was affected by external wind speed, even leading them to become air inlets which would disturb the flow of air indoors, leading to smoke accumulation within the factory.
文摘A new type fully reversible combined blade is presented, which can fully reverse airflow during the inverse ventilation by simply reversion. It is suitable for reversible axial flow fans used in tunnel and mine ventilation. The optimal parameters such as overlap ratio and pitch ratio are determined through cascade experiment. Experiment results also show a big promotion of maximum lift coefficient C1,max and stall attack angle a1,max compared to the existing bi-directional symmetry airfoils.
