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EFFECTS OF OROGRAPHY AND air flow IN EKMAN BOUNDARY LAYER

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Acta meteorologica Sinica 1991年第1期5卷 62-70页

作者：伍荣生 Department of Atmospheric Sciences Nanjing UniversityNanjing

It is convenient to use σ-coordinates to discuss the dynamic effect of orography and the flow in Ekman boundary *** this paper,the theory of mixing length is generalized to the σ-coordinate system. Then the governing equations,describing the motion in the boundary layer over the mountain regions are *** features of flow in the boundary layer,especially the effects of Ekman pumping,are discussed in *** is pointed out that there are three factors affecting the vertical motion at the top of the boun- dary layer:(1)vorticity distribution in the boundary layer,which is directly related to the divergence and convergence of air flow caused by friction,(2)the upslope or downslope motion of flow over the mountain slopes,and(3)the mutual effect of orography and friction induced by the ageostrophic component climbing up- ward or downward in the boundary layer over mountain regions.

关键词： effects of orography air flow boundary layer Ekman pumping

air flow Prediction and Evaluation of Ventilation Effectiveness with Different Zonal Configurations

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Journal of Energy and Power Engineering 2013年第2期7卷 277-282页

作者： Nasreddine Guerfala Hachimi Fellouah Ahmed Daoud Nicolas Galanis Department of Mechanical Engineering Universite de Sherbrooke Sherbrooke JIK 2R1 Quebec Canada The lnstitut de recherche d'Hydro-Quebec (IREQ) Energy Technology Laboratory (L TE) Shawinigan G9N 7N5 Quebec Canada

This paper proposes a numerical method for the study of ventilation efficiency in buildings. The developed model is validated with the experimental results of Nielsen who tested the isothermal flow in a scaled model of a ventilated room. A zonal method is used to predict airflow patterns in the same ventilated room. The different equations governing the flow in the room were coded in Matlab for different operating conditions, different zonal configurations of the room and different number of cells （control volumes）. The efficiency of the ventilation was determined by calculating the number of ACH （air changes per hour） for each cell. The present results show the importance of the inlet air flow rate, the space resolution and the jet inlet dimensions on the determination of air quality.

关键词： air flow zonal method numerical simulation ventilated room ventilation efficiency.

Vacuum and air flow for 2QXP-1 Vacuum Precision Seed Metering

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Journal of Northeast Agricultural University(English Edition) 2013年第2期20卷 61-64页

作者： Su Wei Wang Fu-lin Chen Hai-tao Lai Qing-hui Faculty of Modern Agricultural Engineering Kunming University of Science and Technology College of Engineering Northeast Agricultural University

Vacuum precision seed metering is the key part of vacuum seed planter. Planting performance of planter is affected by vacuum and air flow which are important parameters for choosing fan. Effects of qualification percent and miss percent on air chamber vacuum 3, 4, 5 and 6 kPa were studied at different operating speeds. The results showed that operating performance of the seed metering was excellent when air chamber vacuum was 5 and 6 kPa, which air flow was 7.4-8.0 m3·s-1 and 8.0-8.8 m3·s-1 , respectively.

关键词： seed planter precision seed metering vacuum degree air flow

Three-dimensional DEM-CFD analysis of air-flow-induced detachment of API particles from carrier particles in dry powder inhalers

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Acta Pharmaceutica Sinica B 2014年第1期4卷 52-59页

作者： Jiecheng Yang Chuan-Yu Wu Michael Adams School of Chemical Engineering University of BirminghamBirmingham B152TTUK Department of Chemical and Process Engineering University of SurreyGuildford GU27XHUK

air flow and particle-particle/wall impacts are considered as two primary dispersion mechanisms for dry powder inhalers(DPIs).Hence,an understanding of these mechanisms is critical for the development of *** this study,a coupled DEM-CFD(discrete element method-computational fluid dynamics)is employed to investigate the influence of air flow on the dispersion performance of the carrier-based DPI formulations.A carrier-based agglomerate is initially formed and then dispersed in a uniformed air *** is found that air flow can drag API particles away from the carrier and those in the downstream air flow regions are prone to be ***,the influence of the air velocity and work of adhesion are also *** is shown that the dispersion number(i.e.,the number of API particles detached from the carrier)increases with increasing air velocity,and decreases with increasing the work of adhesion,indicating that the DPI performance is controlled by the balance of the removal and adhesive *** is also shown that the cumulative Weibull distribution function can be used to describe the DPI performance,which is governed by the ratio of the fluid drag force to the pull-off force.

关键词： Dry powder inhaler Dispersion Detachment air flow DEM-CFD

Application of BGK Scheme on Micro-Channel Gas flow

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Chinese Physics Letters 2003年第12期20卷 2199-2202页

作者：孙喜明何枫丁英涛 DepartmentofEngineeringMechanics TsinghuaUniversityBeijing100084

A modified gas kinetic Bhatnagar-Gross-Krook (BGK) scheme for microflow has been developed upon the simultaneous collision model. Based on experimental and numerical results, the sub-choked pressure ratios are investi... 详细信息

关键词： Numerical microchannel flow Scheme PresRto air flow microchannels

Rarefied Gas flow in Rough Microchannels by Molecular Dynamics Simulation

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Chinese Physics Letters 2004年第9期21卷 1777-1779页

作者：曹炳阳陈民过增元 DepartmentofEngineeringMechanics TsinghuaUniversityBeijing100084

The molecular dynamics simulation method is applied to investigate the rarefied gas flow in a submicron channel with surface roughness which is modelled by an array of triangle modules. The boundary conditions are found to be determined not only by the Knudsen number but also the roughness, which implies that the breakdown of the Maxwell slip model under the conditions that the surface roughness is comparable to the molecular mean free path. The effects of the rarefaction and the surface roughness on the boundary conditions and the flow characteristics are strongly coupled. The flow friction increases with increasing roughness and with decreasing Knudsen number.

关键词： Molecular Dynamics Simulation Surface roughness flow characteristics flow friction roughness kinetic simulation air flow microchannels Knudsen flow Boundary conditions rarefaction

Influence of ripening conditions on Scamorza cheese quality

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International Journal of Agricultural and Biological Engineering 2013年第3期6卷 71-79页

作者： Elena Sorrentino L.Tipaldi G.Pannella G.La Fianza M.Succi P.Tremonte Department of Agriculture Environment and FoodUniversity of MoliseCampobasso 86100Italy Institute of Food Sciences National Research Council(ISA-CNR)Avellino 83100Italy

Scamorza is a pasta filata cheese produced in Southern Italy and eaten after a short *** ripening phase is critical in defining the main qualitative features of the Scamorza *** success of this operation is conditioned not only by the process parameters,but also by the characteristics of the ripening room in which different microclimates *** work intended to evaluate the influence of the different positions of cheeses within the ripening room on the evolution of their qualitative characteristics during the process of drying/*** this purpose,samples of Scamorza cheese,produced in the Molise Region(Italy),were divided into two batches(C and L)and subjected to ripening for seven days in a thermo thermo-regulated *** two batches were placed in different points of the room:the batch C in the central area and the batch L in the lateral *** the ripening,temperature,humidity and air flow were monitored and the Scamorza cheeses were analysed to assess some qualitative *** a ripening room,the created microclimates are able to influence the quality of the product,as demonstrated by data related to temperature,humidity and air *** fact,from the results obtained,some appreciable differences among products from batches C and L were observed for the weight loss,the water activity and the colorimetric *** in the behaviour of mesophilic lactic acid bacteria,pH and acidity were also *** more rapid loss of water,characterizing the batch C,resulted in an evolution of physicochemical,physical and microbiological features,which resulted different from those observed in the samples from the batch ***,the results obtained in this study point out that,within the ripening room,the formation of different micro-environments is able to strongly influence the definition of the qualitative characteristics of the products placed in it.

关键词： pasta filata cheese ripening drying cheese quality Lactic acid bacteria air flow ripening room

Exploring the Efficiency of Experimental Construction of Sorting Ginned Cotton Seed Machine

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Engineering（科研） 2021年第1期13卷 18-29页

作者： Avazbek Оbidov Muhiddin Vokhidov Jahongir Abdurahmonov Namangan Institute of Engineering and Technology Namangan Uzbekistan

In this paper, research has been conducted to increase the quantity of fiber produced in the enterprise by creating a sorting device for spun seeds, dividing them into fractions by geometric dimensions, and by re-ginning, separating those with long fibers. A new model was developed for geometric sorting of cotton seeds in the harvest, and experiments determined its effectiveness and the optimal values of the factors affecting the efficiency using mathematical modeling. Based on the results of the study, graphs of the influence of factors on device performance and on device efficiency were constructed.

关键词： Cotton Seeds Cotton Fiber Fractions Sorting Machine Short Fiber air flow Vibration Machine Vibration Frequency

NUMERICAL STUDY ON THE INTERACTION OF ELECTRICAL ARC-GAS flow NEAR CURRENT ZERO IN A SF6 SELF-BLAST INTERRUPTER

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NUMERICAL STUDY ON THE INTERACTION OF ELECTRICAL ARC-GAS FLO...