旋转涡旋管分离器分离效率数值分析

对一种具有可旋转叶片的新型旋转涡旋管分离器性能进行数值模拟,分析该涡旋管分离器颗粒大小、叶片数、出口压力、叶片转速4个参数对分离器分离效率的影响。通过正交试验设计方法和ANSYS Fluent软件进行数值计算,仿真结果研究表明,涡旋管分离器设计参数对分离效率影响从大到小依次为颗粒大小、叶片数、出口压力、叶片转速。该旋转涡旋管分离器可以有效分离固体颗粒和气体,分离效率可高达98%以上,研究结果为涡旋管分离器优化设计奠定基础。

海洋涡旋自动探测几何方法、涡旋数据库及其应用

近10a来,海洋涡旋的自动探测和分析研究成为物理海洋学研究的前沿热点之一。本研究介绍了作者及其合作者最近几年发展的一系列基于海表面高度异常(Sea Surface Height Anomaly,SSHA)、海表温度(Sea Surface Temperature,SST)的欧拉型以及基于全球漂流浮标数据的拉格朗日型的涡旋自动探测几何方法、从欧拉型涡旋探测方法中发展出来的三维涡旋的自动探测方法和利用上述方法探测得到的结果建立的涡旋数据库。此外,本研究还介绍了涡旋数据库的应用,主要包括:分析黑潮延续体以及南加州湾的涡旋统计特征;以黑潮延伸区冷、暖两个中尺度涡旋为例,采用动态合成、带通滤波等方法,研究中纬度地区中尺度海洋涡旋对大气的强迫特征;在黑潮延续体采用合成分析方法得到了合成气旋和反气旋的三维结构并对涡旋调制下混合层深度进行探究;对涡旋诱导的输运、涡旋诱导的叶绿素变化进行的研究以及对阿拉伯海大涡进行的研究等。

2013年7月3日山西南部区域性大暴雨中分析

2013年7月3日山西南部出现区域性大暴雨天气过程，19个县达到暴雨，其中8个县降水量≥100mm，1小时最大雨强54．6mm。利用常规气象观测资料、地面加密自动站资料、卫星云图资料、雷达资料，对此次区域性大暴雨成因进行中分析，结果表明：①）此次大暴雨过程发生在两槽一脊、副高稳定、200hPa反气旋的大尺度环流背景下，强的条件不稳定、超低空急流加强、低层正涡度、强的上升气流是大暴雨发生的环境条件，大暴雨发生在湿区梯度锋上。②大暴雨由午后热对流产生的暴雨云团和中尺度对流系统造成，热对流云团发生在超低空急流左前侧、山西南部中条山、王屋山的迎风坡和喇叭口地形收缩处，地形抬升作用触发热对流发生；中尺度对流系统由4个对流云团组成，地面中尺度涡旋是中尺度对流系统的主要触发系统。

Study on the Meso-scale process of the Kuroshio front to the east of Taiwan

By using the reanalysis data, the impact of oceanic eddies and frontal wave on Kuroshio front to the east of Taiwan （KFETW） is studied. The result indicates that cold eddies （warm eddies） corresponding to the first baroclinic mode of Rossby wave can weaken （strengthen） the strength of the KFETW and narrow （widen） the width of this front. A frontal wave of the KFETW during January to February in 1991 is detected from the reanalysis data. And the trough （crest） of the frontal wave may weaken （strengthen） the strength of the KFETW and narrow （widen） the width and thickness of this front. It is found through the diagnostic analysis of the energy source of the frontal wave that the contribution of barotropic instability or that of baroclinic instability is more than that of Ketvin-Helmholtz （K-H） instability by 1 - 2 order of magnitude, and the contribution of the baroclinic instability is 5 times than that of the barotropic instability, thereby the frontal wave is basically driven by the baroclinic instability.

Theoretical and Experimental Analysis of Vortex Origin

Several investigations refer to the issue of creation and identification of vortices in flows with different regime and presence of obstacles. Reasons have to do with the crucial role that vortices play in nature and industrial processes （sediment transport, mixing, radiation, noise, etc.）. Despite the contributions, further work is needed in order to perform more analysis of the mathematical arguments used to explain this phenomenon. In this idea order, the paper presents some advances in mathematical analysis and experimental results. In the first section, we do a description of the fluid motion from a fractional view through a sequence of three steps： Darcy＇s law, Navier-Stokes equations and Reynolds equations. Next, a representation of the temporal change of kinetic energy is found, which allows the possibility of the two signs. We obtain a description of the process of vortex creation. A length that represents the transition between flow and vortex intensity is found; then a succession of lengths is established that allows scaling from micro to macro. In the second section, experimental results are present; we consider vortex creation and its detection upstream of a bed form similar to that found in rivers, installed in an open channel, equipped with a water circulation system. For vortex detection, a methodology based on the particle image velocimetry PIV technique is proposed. So, we fulfill two objectives： vortex identification and its passage frequencies behind the bed form installed in the channel. Such procedure allows a computer process time reduction in vortices identification task.

A Parametric Study for High-Efficiency Gas-Liquid Separator Design

A gas liquid centrifugal separator is widely used in industry on account of its simple geometry and little maintenance. These separators have considerable advantages over filters, scrubbers or precipitators in term of compact design, lower pressure drop and higher capacity. A gas liquid centrifugal separator is a device that utilizes centrifugal forces and low pressure caused by rotational motion to separate liquid from gas by density differences. Efficient and reliable separation is required for the optimum operation. These separators are often operated at less than peak efficiency due to the entrainment of separated liquid through an outlet pipe which is closely associated with the very complicated flow phenomena involved. Design parameters such as length of the separation space, vane exit angle, inlet to outlet diameter ratio, models for separation efficiency and pressure drop as a function of physical dimensions are not available in literature. This leaves the designer with very little to go on except known designs and experimentation. The aim of present study is to perform a parametric study to get higher efficiency for gas-liquid separator. A parametric study has been carded out with the help of CFD tools to analyze a separation performance of a centrifugal separator by varying the length of separator space. The best design parameters are analyzed based upon obtained results, tangential velocities, vortices, total pressure losses. From the present study several attempts are made to improve the performance of conventional centrifugal separators.

Performance analysis of a single-stage scroll compressor used in a drying heat pump over a wide condensing temperature range(30–80°C)

This study presents the performance of a new single-stage scroll compressor used for the heat pump drying of thermally sensitive materials over a wide temperature range. The performance of the new compressor was predicted by an ARI standard 540 map-based compressor model and verified by a semi-open drying heat pump system constructed for this purpose. A comparison of the experimental data with the predicted data proved that the new scroll compressor used in the drying heat pump works well, can supply a wide range of condensing temperatures （30--80℃） （without auxiliary heating）, and has a minimum coeffi- cient of performance （COP） above 2.0, even in the worst condition.

Numerical predictions and stability analysis of cavitating draft tube vortices at high head in a model Francis turbine

Draft tube vortex is one of the main causes of hydraulic instability in hydraulic reaction turbines,in particular Francis turbines.A method of cavitation calculations was proposed to predict the pressure fluctuations induced by draft tube vortices in a model Francis turbine,by solving RANS equations with RNG k-turbulence model and ZGB cavitation model,with modified turbulence viscosity.Three cases with different flow rates at high head were studied.In the study case of part load,two modes of revolutions with the same rotating direction,revolution around the axis of the draft tube cone,and revolution around the core of the vortex rope,can be recognized.The elliptical shaped vortex rope causes anisotropic characteristics of pressure fluctuations around the centerline of the draft tube cone.By analyzing the phase angles of the pressure fluctuations,the role of the vortex rope as an exciter in the oscillating case can be recognized.An analysis of Batchelor instability,i.e.instability in q-vortex like flow structure,has been carried out on the draft tube vortices in these three cases.It can be concluded that the trajectory for study case with part load lies in the region of absolute instability(AI),and it lies in the region of convective instability(CI)for study case with design flow rate.Trajectory for study case with over load lies in the AI region at the inlet of the draft tube,and enters CI region near the end of the elbow.