Taking into account moisture in virtue of general potential temperature,the author derive a three-dimensional(3D) pseudomomentum wave-activity relation for the moist atmosphere from the primitive equations in Cartesia...Taking into account moisture in virtue of general potential temperature,the author derive a three-dimensional(3D) pseudomomentum wave-activity relation for the moist atmosphere from the primitive equations in Cartesian coordinates using the Momentum-Casimir method.Since the wave-activity relation is constructed in an ageostrophic and non-hydrostatic dynamical framework,it may be applicable to diagnosing the evolution and propagation of mesoscale systems leading to heavy rainfall.The theoretical analysis shows that,besides the local change of wave-activity flux divergence and source or sink,the wave-activity relation includes two additional forcing terms.The first is the zonal gradient of difference between general potential temperature and potential temperature perturbations,and the second is the covariance of the solenoid and gradient of water vapor,denoting the direct influence of moisture on wave-activity density.The wave-activity density was applied to a heavy precipitation event occurring in the Jianghuai region of China.The calculation showed that the wave-activity density was consistent with 6-h accumulated precipitation observations,in terms of both spatial distribution and temporal tendency.This suggested that the disturbance represented by wave-activity density was closely related to the heavy precipitation.Although the wave-activity flux divergence and the covariance of the solenoid and gradient of water vapor made the primary contribution to the local change of wave-activity density,the covariance was more remarkable.The zonal gradient of difference between general potential temperature and potential temperature perturbations made a weaker contribution to the waveactivity density.展开更多
In recent years,separating and extracting technologies of condensate gas have been developed by combining a swirl flow with non-equilibrium condensation phenomena of condensate gas generated in a supersonic flow.The t...In recent years,separating and extracting technologies of condensate gas have been developed by combining a swirl flow with non-equilibrium condensation phenomena of condensate gas generated in a supersonic flow.The technology can reduce the size of the device and does not use chemicals.However,there are many unresolved problems for performance of the separation,extraction and operating principle.Therefore it is necessary to research further in order to improve the performance of the equipment.In the present study,the numerical study was carried out to clarify the effect of the heterogeneous condensation on the characteristics of the swirling flow field in a supersonic annular nozzle,and the differences between homogeneous condensation and heterogeneous condensation in the flow field.As the results,it is found that the condensation flow with a swirl affects the position of sonic line,the generating position of condensate and the radial distribution ratio of liquid phase.展开更多
To explore the condensation characteristics of vapor flow inside vertical small-diameter tubes, the classical Nusselt theory is revised and an analytical model with variable tube wall temperature is established by con...To explore the condensation characteristics of vapor flow inside vertical small-diameter tubes, the classical Nusselt theory is revised and an analytical model with variable tube wall temperature is established by considering the effect of surface tension exerted by condensate film bending as well as the effect of shear stress on vapor-liquid interface. The effects of various factors including tube wall temperature and gravityon flow condensation in small-diameter tubes are analyzed theoretically to show the heat transfer characteristics. Comparison with the experimental data indicates that the proposed analytical model is fit to reveal the fundamental characteristics of flow condensation heat transfer in vertical small-diameter tube.展开更多
基金supported by the National Basic Research Program of China (Grant No.2009CB421505)the Key Program of the Chinese Academy of Sciences (Grant No.KZZD-EW-05)+2 种基金the project of Chinese Academy of Meteorological Sciences (Grant No.2011LASW-B15)the Spectial Scientific Research Fund of Meteorological Public Welfare of the Ministry of Sciences and Technology (Grant No.GYHY200906004)and the National Natural Science Foundation of China (Grant Nos.41175060,41075098,and 41005005)
文摘Taking into account moisture in virtue of general potential temperature,the author derive a three-dimensional(3D) pseudomomentum wave-activity relation for the moist atmosphere from the primitive equations in Cartesian coordinates using the Momentum-Casimir method.Since the wave-activity relation is constructed in an ageostrophic and non-hydrostatic dynamical framework,it may be applicable to diagnosing the evolution and propagation of mesoscale systems leading to heavy rainfall.The theoretical analysis shows that,besides the local change of wave-activity flux divergence and source or sink,the wave-activity relation includes two additional forcing terms.The first is the zonal gradient of difference between general potential temperature and potential temperature perturbations,and the second is the covariance of the solenoid and gradient of water vapor,denoting the direct influence of moisture on wave-activity density.The wave-activity density was applied to a heavy precipitation event occurring in the Jianghuai region of China.The calculation showed that the wave-activity density was consistent with 6-h accumulated precipitation observations,in terms of both spatial distribution and temporal tendency.This suggested that the disturbance represented by wave-activity density was closely related to the heavy precipitation.Although the wave-activity flux divergence and the covariance of the solenoid and gradient of water vapor made the primary contribution to the local change of wave-activity density,the covariance was more remarkable.The zonal gradient of difference between general potential temperature and potential temperature perturbations made a weaker contribution to the waveactivity density.
文摘In recent years,separating and extracting technologies of condensate gas have been developed by combining a swirl flow with non-equilibrium condensation phenomena of condensate gas generated in a supersonic flow.The technology can reduce the size of the device and does not use chemicals.However,there are many unresolved problems for performance of the separation,extraction and operating principle.Therefore it is necessary to research further in order to improve the performance of the equipment.In the present study,the numerical study was carried out to clarify the effect of the heterogeneous condensation on the characteristics of the swirling flow field in a supersonic annular nozzle,and the differences between homogeneous condensation and heterogeneous condensation in the flow field.As the results,it is found that the condensation flow with a swirl affects the position of sonic line,the generating position of condensate and the radial distribution ratio of liquid phase.
基金This work was supported by the National Natural Science Foundation of China (Grant No. 59995550-3) .
文摘To explore the condensation characteristics of vapor flow inside vertical small-diameter tubes, the classical Nusselt theory is revised and an analytical model with variable tube wall temperature is established by considering the effect of surface tension exerted by condensate film bending as well as the effect of shear stress on vapor-liquid interface. The effects of various factors including tube wall temperature and gravityon flow condensation in small-diameter tubes are analyzed theoretically to show the heat transfer characteristics. Comparison with the experimental data indicates that the proposed analytical model is fit to reveal the fundamental characteristics of flow condensation heat transfer in vertical small-diameter tube.
