The Modified Envelope Orography and the Air Flow over and around Mountains

By use of the two-layer adiabatic globe spectral model and the zonally averaged climatic data of winter season as initial values, 10-day integrations are carried out based on three kinds of model topography (i.e., (1) the averaged topography; (2) the envelope topography; (3) the modified envelope topography). The results show that the orography of the Northern Hemisphere plays an important role in the simulation of large-scale weather patterns in winter season. The simulation based on the envelope topography developed by Wallace et al. has some improvements in the Rocky Mountains area. But this scheme causes very serious horizontal expansion around the Tibetan Plateau (hereafter referred to as the TV). A modified envelope topography scheme has been worked out that increases the slope of the TP by decreasing the horizontal expansion while keeping the maximum altitude. The results show some improvements of the scheme around the TP. By analysis of the mechanical effects of the large-scale orography on the currents, the different forcings of the air flow over and around the TP and the Rocky Mountain (the RM) are investigated.

Surface Decontamination of Chemical Agent Surrogates Using an Atmospheric Pressure Air Flow Plasma Jet

An atmospheric pressure dielectric barrier discharge （DBD） plasma jet generator using air flow as the feedstock gas was applied to decontaminate the chemical agent surrogates on the surface of aluminum, stainless steel or iron plate painted with alkyd or PVC. The experi- mental results of material decontamination show that the residual chemical agent on the material is lower than the permissible value of the National Military Standard of China. In order to test the corrosion effect of the plasma jet on different material surfaces in the decontamination pro-cess, corrosion tests for the materials of polymethyl methacrylate, neoprene, polyvinyl chloride （PVC）, polyethylene （PE）, phenolic resin, iron plate painted with alkyd, stainless steel, aluminum, etc. were carried out, and relevant parameters were examined, including etiolation index, chroma- tism, loss of gloss, corrosion form, etc. The results show that the plasma jet is slightly corrosive for part of the materials, but their performances are not affected. A portable calculator, computer display, mainboard, circuit board of radiogram, and a hygrometer could work normally after being treated by the plasma jet.

Air flow control based on optimal oxygen excess ratio in fuel cells for vehicles

Air flow control is one of the most important control methods for maintaining the stability and reliability of a fuel cell system, which can avoid oxygen starvation or oxygen saturation. The oxygen excess ratio （OER） is often used to indicate the air flow condition. Based on a fuel cell system model for vehicles, OER performance was analyzed for different stack currents and temperatures in this paper, and the results show that the optimal OER was affected weakly by the stack temperature. In order to ensure the system working in optimal OER, a control scheme that includes an optimal OER regulator and a fuzzy control was proposed. According to the stack current, a reference value of air flow rate was obtained with the optimal OER regulator and then the air compressor motor voltage was controlled with the fuzzy controller to adjust the air flow rate provided by the air compressor. Simulation results show that the control method has good dynamic and static characteristics.

Improvement of uniformity in cultivation environment and crop growth rate by hybrid control of air flow devices

A complete control type plant factory has high efficiency in terms of cultivation area by constructing vertical multiple layered cultivation beds.However,it has a problem of irregular crop growth due to temperature deviation at upper and lower beds and increases in energy consumption by a prolonged cultivation period.In this work,air flow rate inside a facility was improved by a hybrid control of air flow devices like air conditioning and air circulation fan with an established wireless sensor network to minimize temperature deviations between upper and lower beds and to promote crop growth.The performance of proposed system was verified with an experimental environment or Case A wherein air conditioning device was operated without a control algorithm and Case B wherein air conditioning and circulation fans were alternatively operated based on the hybrid control algorithm.After planting leafy vegetables under each experimental condition,crops were cultivated for 21 days.As a result,Case B wherein AC(air conditioning) and ACF(air-circulation fan) were alternatively operated based on the hybrid control algorithm showed that fresh mass,number of leaves,and leaf length for the crops grown were increased by 40.6%,41.1%,and 11.1%,respectively,compared to Case A.

Vacuum and Air Flow for 2QXP-1 Vacuum Precision Seed Metering

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.

Influence of Air Flow Rate on Functional Evaluation of Semicircular Canals

Objective To study the influence of unilateral air flow rate change on the result of caloric test.Materials and Methods The unilateral weakness(UW) index was calculated when the air flow rate was set at 6 L /min in both ears(called symmetric stimulation) and again when it was set at 6 L /min in left ear and 3 L /min in the right ear(called asymmetric stimulation).Each individual subject was tested with both symmetrical and asymmetrical stimulations.Paired t test was used to examine the differences between results from symmetrical and asymmetrical stimulations.Result UW index decreased in response to asymmetrical stimulation.Conclusion Unilaterally decreased air flow rate can produce indices suggesting ipsilateral UW,which can be misleading.

A CFD study on optimal venting volume and air flow distribution in a special designed hood system for controlling dust flow

A novel hood structure has been designed for the dust control system in the foundry in order to improve the working environment. A composite strategy has been applied for comparative analysis of the optimal venting volume and the airflow distribution between the conventional hood and the novel one in this study. A Computational Fluid Dynamic (CFD) method is used to simulate the airflow fields and dust-polluted air moving paths. The CFD results show that a two-outlet hood, with one outlet located on the left of the hood, is better for improving dust-polluted air than the hood with one outlet only. It can be concluded that the number of the outlets as well as their location on the hood has a significant influence on the air flow pattern in the hood. The optimal venting volume is also a major consideration that is discussed in the study. The venting volume should be designed by considering both the effective level of air flow velocity around the dust source and the energy saving. The optimal airflow distribution may reduce the turbulence in the hood system.

Air flow patterns and noise analysis inside high speed angular contact ball bearings

The vortex formed around the rolling ball and the high pressure region formed around the ball-raceway contact zone are the principle factors that barricades the lubricant entering the bearing cavity, and further causes improper lubrication. The investigation of the air phase flow inside the bearing cavity is essential for the optimization of the oil-air two-phase lubrication method. With the revolutionary reference frame describing the bearing motion, a highly precise air phase flow model inside the angular contact ball bearing cavity was build up. Comprehensive factors such as bearing revolution, ball rotation, and cage structure were considered to investigate the influences on the air phase flow and heat transfer efficiency. The aerodynamic noise was also analyzed. The result shows that the ball spinning leads to the pressure rise and uneven pressure distribution. The air phase velocity, pressure and cage heat transfer efficiency increase as the revolving speed increases. The operating noise is largely due to the impact of the high speed external flow on the bearing. When the center of the oil-air outlet fixes near the inner ring, the aerodynamic noise is reduced. The position near the inner ring on the bigger axial side is the ideal position to fix the lubricating device for the angular contact ball bearing.

Air flow calculation of reverse circulation drilling technique with air DTH hammer

Air DTH hammer has been successfully applied in minor-caliber solid mineral exploration,water-well drilling and other drilling areas. In order to expand the applications of the technology,the authors further studied the principle and analyzed the mechanism of reverse circulation drilling technique with air DTH hammer to get the perfect assembles of equipments by optimizing working parameters. No parameter seemed more important than the air volume because it could maintain the working performance stability. The minimum air volume is related to the parameters such as depth and pressure,which was calculated under the actual conditions. It was solved for the air injection flow tables of the air DTH Hammer working at the different pressures. According to the data tables,operators could adjust the air volume to meet the demand on this technique,which had a realistic guiding significance. So it could build up a set of systematic and complete hi-technique.

Nose and Sinus Air Flow Model

Air flow in nose and sinuses is studied by means of a simple model based on the steady-state ideal fluid flow assumption and repeated use of Bernoulli’s equation. In particular, by describing flow of air drawn in through the vestibulumnasi during inspiration, we investigate how ventilation of the maxillary sinus is affected by surgical removal of part of the lateral walls of the nasal cavity close to the ostiummeatal complex. We find that, according to the model proposed, removal of tissues from this inner part of the nasal cavity may cause a decrease of the flux rate from the maxillary sinus.

Impact of the Housing on the Air Flow and the Thermal Behavior of an Automotive Clutch System

New directives and increasing competition push automakers to get better performances (engine power increase), along with mass and size reduction (consumption). These evolutions lead to an increase of the thermal solicitations undergone by the automotive clutches whereas their weight must be decreased, as it is one of the main influent factors on CO2 emissions. Previous studies only focused on the air flow created by the clutches, but none of them have shown the impact of the clutch housing on the cooling of the clutch parts. In order to determine the influence of the clutch housing on the thermal behavior of automotive clutch systems, a numerical study has been performed on a simplified model of a clutch system. A parametric variation has been performed on the clutch housing size in order to evaluate its impact on the flow and the thermal behavior of clutches. The results show that clutch housing has a significant impact on the air flow and the thermal behavior of clutches. Thermal tests on real clutches with and without clutch housing have confirmed these results.

基于Flowmaster的小流量供水设备调节性能模拟

现有的二次供水研究对小流量工况关注较少,小流量工况下主泵低效运行、频繁启停问题正成为制约城市供水“最后一公里”低能耗、高质量发展的痛点。为此,建立Flowmaster仿真模型对“工频辅泵+气压罐”小流量供水模式进行模拟,探究了需求侧不同小流量下气压罐的调节性能。结果表明,“工频辅泵+气压罐”可很好减少水泵启停次数,保持系统稳定。进一步研究了气压罐预充压力对调节性能的影响,阐明了预充气泄漏带来的负面影响,并提出相关工程建议。

Numerical simulation and experimental verification on downwash air flow of six-rotor agricultural unmanned aerial vehicle in hover

Recently,multi-rotor unmanned aerial vehicle(UAV)becomes more and more significantly irreplaceable in the field of plant protection against diseases,pests and weeds of crops.The easy takeoff and landing performance,hover function and high spraying efficiency of UAV are urgently required to spray pesticide for crop timely and effectively,especially in dispersed plots and hilly mountains.In such situations,the current researches about UAV spray application mainly focus on studying the influence of the UAV spraying parameters on the droplet deposition,such as operation height,operation velocity and wind velocity.The deposition and distribution of pesticide droplets on crops which depends on installation position of nozzle and airflow distribution characteristics of UAV are directly related to the control effect of pesticide and crop growth in different growth periods.As a preliminary step,this study focuses on the dynamic development law and distribution characteristics of the downwash air flow for the SLK-5 six-rotor agricultural UAV.Based on compressible Reynolds-averaged Navier-Stokes(RANS)equations with an RNG k-εturbulence model and dynamic mesh technology,the efficient three-dimensional computational fluid dynamics(CFD)method was established to analyze the flow field distribution characteristics of UAV in hover.Then the unsteady interaction flow field of the wing was investigated in detail.The downwash wind speed of the marked points for the SLK-5 UAV in hover was also tested by weather tracker.It was found that the maximum velocity value of the downwash flow was close to 10 m/s;the z-direction velocity was the main body of the wind velocity in the downwash airflow,and the comparison of the wind velocity experiment test and simulation showed that the relative error was less than 12%between the experimental and simulated values of the z-direction velocity at the marked points.Then the flow characteristics of the longitudinal and cross section were analyzed in detail,the results obtained can be used as a reference for drift and sedimentation studies for multi-rotor unmanned aerial vehicle.

Simulating the air flow in the conveying pipe of the foreign fiber detection device

Cotton bales are frequently intermingled with foreign fibers which will interfere in the process of spinning,weaving and dyeing and will worsen the product quality.Nowadays,cotton fibers are sorted manually in most of the cotton textile mills with very low efficiency.There is a great demand for foreign fiber detection devices in Chinese cotton textile mills.The air flow in the conveying pipe of the device has an important effect on the image acquisition,image analysis and removal of foreign fibers.As a primary effort,the air flow in the conveying pipe of the foreign fiber detection device was simulated numerically.The effects of the inlet air velocity on the air turbulence intensity and air velocity along the detecting section were studied.

Design and performance of air flow-assisted ionization imaging mass spectrometry system

The imaging mass spectrometry（IMS） technology has experienced a rapid development in recent years.A new IMS technology which is based on air flow assisted ionization（AFAI） was reported.It allows for the convenient pretreatment of the samples and can image a large area of sample in a single measurement with high sensitivity.The AFAI in DESI mode was used as the ion source in this paper.The new IMS method is named AFADESI-IMS.The adoption of assisted air flow makes the sample pretreatment easy and convenient.An optimization of the distance between the ion transport tube and MS orifice increases the sensitivity of the system.For data processing,a program based on MATLAB with the function of numerical analysis was developed.A theoretical imaging resolution of a few hundred microns can be achieved.The composite AFAI-IMS images of different target analytes were imaged with high sensitivity.A typical AFAI-IMS image of the whole-body section of a rat was obtained in a single analytical measurement.The ability to image a large area for relevant samples in a single measurement with high sensitivity and repeatability is a significant advantage.The method has enormous potentials in the MS imaging of large and complicated samples.

EFFECTS OF OROGRAPHY AND AIR FLOW IN EKMAN BOUNDARY LAYER

It is convenient to use σ-coordinates to discuss the dynamic effect of orography and the flow in Ekman boundary layer.In 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 derived.The features of flow in the boundary layer,especially the effects of Ekman pumping,are discussed in details.It 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.

Effects of herba menthae, borneolum and moschus on nasal sensation of air flow and nasal resistance

Objective Herba menthae, Borneolum and moschus are strongly volatile. Herba menthae, borneolum have been widely used as traditional Chinese medicines in the treatment of nasal congestion. The aim of this study was to determine the effects of herba menthae, borneolum and moschus on nasal sensation of airflow and nasal resistance. Method 52 volunteers (32 females, 20 males, aged from 19 to 32 years) were studied. Only subjects with normal nose functions were included in the study. Those who had had a coryzal illness or allergic rhinitis during the last three weeks excluded from the study. Nasal resistance was measured by active anterior rhinomanometry, using Master PF 2001 rhinomanometry (ICS Corporation, U.S.A.). Nasal sensation was measured with a self made equipment, called “nasal sensation indication scale”. There was a 100cm line scale on the equipment. Each end of the 100cm line scale was defined as either “extremely clear” or “extremely blocked”. The slide control was brought to the center point of the 100cm scale before each scoring of nasal sensation. The center point was the zero point for the scoring of nasal sensation. Each subject expressed his subjective feelings of nasal sensation of airflow by moving the slide control to the appropriate direction. Substances were administered by self made wick inhaler which consisted of a vessel in which the substances were put and a capsule which can spray air. Inhalers A, B, C and D respectively contained a blank wick, herba menthae at a concentration of 100mg dissolved in 1ml vaseline, borneolum at a concentration of 100mg dissolved in 1ml vaseline, moschus Department of Otorhinolaryngology Head and Neck Surgery, Third Clinical College of Bethune University of Medical Sciences, Changchun 130031, China (Wang YP, Dong Z, Yang ZQ and Bu GX) 1g. Each nostril was sprayed three times during the experiment, first the left and then the right. The protocol was as follows. Nasal resistance was measured before the administration of substances. Air control was first administered, followed by the other three kinds of medicines which were administered randomly, so that bias resulting from the order of presentation of substances would be controlled in the final analysis of the results. After inhalation of medicines, nasal sensation and nasal resistance were measured in order. Every two kinds of medicine were administered at an interval of 15 minutes so that any delayed effects could be observed. Results Because original data of nasal resistance and nasal sensation were not normal distribution, the logarithm of the original data were used for statistic analysis. Inhalation of herba menthae, borneolum or moschus all had no obvious influence on nasal resistance (P>0.05), but all caused enhancement of nasal sensation of airflow (P<0.01). Among these medicines the action of herba menthae was the strongest, borneolum and moschus being the second. 4 subjects had a sensation of nasal obstruction after inhalation of the substance, but there was no corresponding increase in nasal resistance. Conclusion The above results clearly demonstrate that herba menthae, borneolum and moschus all cause a highly significant enhancement of nasal sensation of airflow, but had no obvious effects on nasal resistance, in other words, enhancement of sensation of nasal airflow was not accompanied by the decrease of nasal resistance (increase of airflow). Therefore, the enhancement of airflow sensation is just a subjective, false impression and this sort of medicine should be regarded as pseudonasal decongestant.

Flow Development Through HP&LP Turbines,PartⅡ:Effects of the Hub Endwall Secondary Sealing Air Flow on the Turbine's Mainstream Flow

Although many literatures have been focused on the underneath flow and loss mechanism, very few experiments and simulations have been done under the engines' representative working conditions or considering the real cavity structure as a whole. This paper aims at realizing the goal of design of efficient turbine and scrutinizing the velocity distribution in the vicinity of the rim seal. With the aid of numerical method, a numerical model describing the flow pattern both in the purge flow spot and within the mainstream flow path is established, fluid migration and its accompanied flow mechanism within the realistic cavity structure(with rim seal structure and considering mainstream & secondary air flow's interaction) is used to evaluate both the flow pattern and the underneath flow mechanism within the inward rotating cavity. Meanwhile, the underneath flow and loss mechanism are also studied in the current paper. The computational results show that the sealing air flow's ingestion and ejection are highly interwound with each other in both upstream and downstream flow of the rim seal. Both the downstream blades' potential effects as well as the upstream blades' wake trajectory can bring about the ingestion of the hot gas flow within the cavity, abrupt increase of the static pressure is believed to be the main reason. Also, the results indicate that sealing air flow ejected through the rear cavity will cause unexpected loss near the outlet section of the blades in the downstream of the HP rotor passages.

The measurement error analysis when a pitot probe is used in supersonic air flow

Pitot probes enable a simple and convenient way of measuring mean velocity in air flow.The contrastive numerical simulation between free supersonic airflow and pitot tube at different positions in supersonic air flow was performed using Navier-Stokes equations,the ENN scheme with time-dependent boundary conditions (TDBC) and the Spalart-Allmaras turbulence model.The physical experimental results including pitot pressure and shadowgraph are also presented.Numerical results coincide with the experimental data.The flow characteristics of the pitot probe on the supersonic flow structure show that the measurement gives actually the total pressure behind the detached shock wave by using the pitot probe to measure the total pressure.The measurement result of the distribution of the total pressure can still represent the real free jet flow.The similar features of the intersection and reflection of shock waves can be identified.The difference between the measurement results and the actual ones is smaller than 10%.When the pitot probe is used to measure the region of L=0-4D,the measurement is smaller than the real one due to the increase of the shock wave strength.The difference becomes larger where the waves intersect.If the pitot probe is put at L=8D-10D,where the flow changes from supersonic to subsonic,the addition of the pitot probe turns the original supersonic flow region subsonic and causes bigger measurement errors.