During mid-January 2011,a rarely seen twin-extratropical-cyclone event appeared over the western North Pacific Ocean.One of the twin cyclones developed into an extreme explosive extratropical cyclone(EEC),which was co...During mid-January 2011,a rarely seen twin-extratropical-cyclone event appeared over the western North Pacific Ocean.One of the twin cyclones developed into an extreme explosive extratropical cyclone(EEC),which was comparable to the intensity of a typhoon.Rotational and divergent wind kinetic energy(KE)analyses were applied to understand the low-level wind’s rapid enhancement associated with the cyclone.It was found that:(i)the total wind KE associated with the EEC showed a remarkable enhancement in the lower troposphere during the cyclone’s maximum development stage,with the maximum/minimum wind acceleration appearing in the southeastern/northwestern quadrant of the EEC;(ii)the rotational wind KE experienced an obvious increase,which corresponded to the total wind KE enhancement,whereas the divergent wind KE,which was much smaller than the rotational wind,mainly featured a decreasing trend;(iii)the rotational wind KE enhancement showed variational features consistent with the horizontal enlargement and upward stretching of the EEC;(iv)the nonorthogonal wind KE enhanced the total wind KE in regions with strong rotational wind,which resulted in the maximum lower-tropospheric maximum wind,whereas in regions with strong divergent wind it mainly reduced the total wind KE;(v)the northward transport of total wind KE and the rotational wind KE production due to the work done by pressure gradient force were dominant factors for the enhancement of winds associated with the EEC,particularly in its southeastern section.In contrast,an overall conversion from rotational wind KE to divergent wind KE decelerated the rotational wind enhancement.展开更多
An analysis of the kinetic energy budget is made for a tropical cyclone. Horizontal flux convergence constitutes a major energy source. Generation of kinetic energy via cross-contour flow is a persistent sink througho...An analysis of the kinetic energy budget is made for a tropical cyclone. Horizontal flux convergence constitutes a major energy source. Generation of kinetic energy via cross-contour flow is a persistent sink throughout the pre-storm and growth periods. Dissipation of kinetic energy from subgrid to grid scales is an important source during the pre-storm and growth periods;it acts as the major sink of energy during the decay period. The major contribution to kinetic energy comes from a persistent upper tropospheric jet stream activity throughout the period of the cyclone development. Unlike midlatitude cyclones, a considerable quantity of kinetic energy appears between 850 - 500 hPa layers especially during the growth period. While the behavior of the values of horizontal divergence by nondivergent wind closely resemble to those of total horizontal divergence term, neglecting the divergent part of the wind would clearly lead to a considerable error in the calculation of total horizontal divergence. The mean error in approximation of total horizontal divergence by the nondivergent part during the life cycle of our cyclone is about 36%.展开更多
There are many types of cyclone dust collectors for separating the fine solid and dust particles from gases in the various industries and also in the home used purposes. For estimating the power loss and the collectio...There are many types of cyclone dust collectors for separating the fine solid and dust particles from gases in the various industries and also in the home used purposes. For estimating the power loss and the collection efficiency, one of the most important factors is the maximum tangential velocity V0m in the vortex core region in the cyclone body. In order to determine V0~ by the simple method, it is useful to apply the mechanical balance of the angular momentum fluxes under the assumption of Ogawa combined vortex model which is composed of the quasi-forced vortex in the vortex core region and also the quasi-free vortex surrounded the vortex core region and also under the assumption of the introduction of equivalent length Heq corresponding to the cone spaces of the cyclone body and the dust bunker. On the other hand, the mean rotational velocity Voi near the concave wall surface is also estimated by the mechanical balance of angular momentum fluxes with the moment of viscous friction force. For confirming the general applications of the obtained equations, the returned flow types cyclones changed the throat diameter D3 are designed. The material of the cyclone is the transparent acrylic resin. Therefore the inner surface of the cyclone body can be regarded as smooth surface. The comparisons of the measured velocities V~ and Voi by a cylindrical Pitot tube are shown in good agreement with those of the proposed equations. The above stated results are described in detail.展开更多
基金supported by the National Key R&D Program of China grant number 2018YFC0809400the National Natural Science Foundation of China grant numbers41775046 and 91637211the Youth Innovation Promotion Association,Chinese Academy of Sciences。
文摘During mid-January 2011,a rarely seen twin-extratropical-cyclone event appeared over the western North Pacific Ocean.One of the twin cyclones developed into an extreme explosive extratropical cyclone(EEC),which was comparable to the intensity of a typhoon.Rotational and divergent wind kinetic energy(KE)analyses were applied to understand the low-level wind’s rapid enhancement associated with the cyclone.It was found that:(i)the total wind KE associated with the EEC showed a remarkable enhancement in the lower troposphere during the cyclone’s maximum development stage,with the maximum/minimum wind acceleration appearing in the southeastern/northwestern quadrant of the EEC;(ii)the rotational wind KE experienced an obvious increase,which corresponded to the total wind KE enhancement,whereas the divergent wind KE,which was much smaller than the rotational wind,mainly featured a decreasing trend;(iii)the rotational wind KE enhancement showed variational features consistent with the horizontal enlargement and upward stretching of the EEC;(iv)the nonorthogonal wind KE enhanced the total wind KE in regions with strong rotational wind,which resulted in the maximum lower-tropospheric maximum wind,whereas in regions with strong divergent wind it mainly reduced the total wind KE;(v)the northward transport of total wind KE and the rotational wind KE production due to the work done by pressure gradient force were dominant factors for the enhancement of winds associated with the EEC,particularly in its southeastern section.In contrast,an overall conversion from rotational wind KE to divergent wind KE decelerated the rotational wind enhancement.
文摘An analysis of the kinetic energy budget is made for a tropical cyclone. Horizontal flux convergence constitutes a major energy source. Generation of kinetic energy via cross-contour flow is a persistent sink throughout the pre-storm and growth periods. Dissipation of kinetic energy from subgrid to grid scales is an important source during the pre-storm and growth periods;it acts as the major sink of energy during the decay period. The major contribution to kinetic energy comes from a persistent upper tropospheric jet stream activity throughout the period of the cyclone development. Unlike midlatitude cyclones, a considerable quantity of kinetic energy appears between 850 - 500 hPa layers especially during the growth period. While the behavior of the values of horizontal divergence by nondivergent wind closely resemble to those of total horizontal divergence term, neglecting the divergent part of the wind would clearly lead to a considerable error in the calculation of total horizontal divergence. The mean error in approximation of total horizontal divergence by the nondivergent part during the life cycle of our cyclone is about 36%.
文摘There are many types of cyclone dust collectors for separating the fine solid and dust particles from gases in the various industries and also in the home used purposes. For estimating the power loss and the collection efficiency, one of the most important factors is the maximum tangential velocity V0m in the vortex core region in the cyclone body. In order to determine V0~ by the simple method, it is useful to apply the mechanical balance of the angular momentum fluxes under the assumption of Ogawa combined vortex model which is composed of the quasi-forced vortex in the vortex core region and also the quasi-free vortex surrounded the vortex core region and also under the assumption of the introduction of equivalent length Heq corresponding to the cone spaces of the cyclone body and the dust bunker. On the other hand, the mean rotational velocity Voi near the concave wall surface is also estimated by the mechanical balance of angular momentum fluxes with the moment of viscous friction force. For confirming the general applications of the obtained equations, the returned flow types cyclones changed the throat diameter D3 are designed. The material of the cyclone is the transparent acrylic resin. Therefore the inner surface of the cyclone body can be regarded as smooth surface. The comparisons of the measured velocities V~ and Voi by a cylindrical Pitot tube are shown in good agreement with those of the proposed equations. The above stated results are described in detail.
