Lateral Airflow Research Articles

Study on the gas phase migration and distribution characteristics in horizontal well air sparging remediation

Horizontal well air sparging (AS) technology has been proven to be efficient in remediating saturated soils and groundwater contaminated with volatile organic compounds (VOCs). Nevertheless, the airflow patterns and the mechanisms governing uniformity in the horizontal well AS process remain elusive, and a quantitative characterization of the zone of influence (ZOI) has yet to be determined. In this study, we employed both model experiments and numerical simulations to investigate the distribution patterns of lateral airflow in horizontal air sparging tubes within a porous medium. The influence of parameters such as air sparging pressure, groundwater flow, the inclination angle of the air sparging tubes, and the diameter of the medium particles on the distribution patterns of gas-phase transport in horizontal well AS was analyzed. The results show that both groundwater flow and the inclination of air sparging tubes disrupt the uniformity of gas distribution. The ZOI area of AS is observed as an oblong shape in the horizontal plane and a parabolic contour along the boundaries. Additionally, a mutual influence is identified between groundwater flow and AS airflow. Furthermore, the inclination of air sparging tubes results in the formation of preferential flow near the air source end. The ZOI of horizontal AS demonstrates a positive correlation with air sparging pressure and a negative correlation with medium particle diameter. All of the results elucidated above provide valuable information for the design and theoretical modelling of AS within horizontal wells for groundwater remediation.

Effect of Lateral Airflow on Initial HSI and Flame Behavior of Marine Fuel in a Ship Engine Room: Experiment and Analysis

The flame behavior of engine fires, such as those caused by leaked fuel coming into contact with an ignition source, is significant in practical applications, where flame detection is used to minimize the damage of the attendant ship fire safety problem. In this work, the flame behavior of hot-surface ignition (HSI) under crossflow was studied, with a particular focus on the difference in lateral airflow velocities for HSI-driven flame deviations at the windward and leeward sides of a ship engine room; a problem such as this has not previously been quantified. Full-scale experiments were conducted in a ship engine room using marine diesel and hydraulic oil as the fuel, and by adopting lateral airflow with the velocities of 0 m/s, 1.0 m/s, 3.0 m/s, and 5.0 m/s, together with an HSI mechanism consisting of marine diesel and hydraulic oil coming into contact with elevated hot-surface temperatures. The results show that the effects of disturbing the combustible gaseous mixture for marine fuel HSI, at both the windward and leeward sides, strengthened as the airflow velocity increased. The HSI position of the leaked marine fuel in the engine room was strongly dependent on ventilation, while that under the airflow condition decreased with the increase in the hot-surface temperature. A model was proposed to characterize this difference on the basis of the HSI height, which was defined as the ratio of the height during the initial HSI to the stationary period. The results indicate that the scale of the flame gradually increased in the horizontal direction, which was significantly different from the result in the scenario without mechanical ventilation. The results also revealed that the fluctuation of hydraulic oil through the temperature field was significant and lasted for a long time under a low HSI temperature.

Articulatory and acoustic characteristics of occlusivized sonorants in Shakou Hakka

This study examines a pattern of sonorant occlusivization in a dialect of Hakka Chinese spoken in Shakou Township, Guangdong, China. This variety exhibits variable occlusivization of /l/ (realized as centralized [ld ∼ ld ∼ d]) and denasalization of initial /m, ŋ/ (realized as prenasalized stops [?b, ?g]). Mid-sagittal and coronal ultrasound with synchronized audio, EGG, and nasalance recordings were collected from one speaker, along with acoustic recordings from 5 speakers. Partial occlusivization of /l/ occurred in 74.8% of words with high /i, y, u/ but does not occur in words containing low or mid vowels. Occlusivization of /l/ has an average duration of 42ms and is characterized by a significant decrease in mid-frequency acoustic energy (−6 dB, p < 0.001). Ultrasound data reveal tongue body raising and parasagittal contact during occlusivization, indicative of overlap between the tongue gestures required for /l/ (with lateral airflow) vs. /i, y, u/ (with lateral bracing). Denasalization, which has a similar mean duration of 39.5ms, occurs in 42.9% of words containing non-high vowels and 86.25% of words containing high vowels. Although these patterns differ with regard to their phonological conditioning, gestural interaction during sonorant-vowel sequences may provide a common underlying mechanism for both processes.

Research on the Influence of Airfoil on the Flying Performance of Glider

Gliders are heavier-than-air fixed-wing aircraft that do not rely on power plants to fly, and are now widely used in scientific observation, daily entertainment, and other fields. After taking off, it only relies on the reaction force of air acting on its lifting surface for free flight. Different gliders can stay in the air for different amounts of time in different environments, which is mainly determined by the airfoil. Therefore, through literature reading, this paper understands its flight principle, and studies and analyzes the advantages and disadvantages of existing airfoils by comparing the influence of different airfoils on flight performance. In view of the problems existing in the airfoil, rationality calculations and improvements are put forward, hoping to promote the development of the aviation industry. After research, the concave wing is by far the most suitable gliding airfoil, which can provide relatively large lift and stability, but there is still the problem of insufficient load. In order to improve these deficiencies, the airfoil is optimized by increasing the contact area between the airflow and the wing. For example, the defect can be improved by lengthening the length of the entire wing, reducing lateral airflow, and increasing the upward curvature of the wingtip.

Numerical simulation of social distancing of preventing airborne transmission in open space with lateral wind direction, taking into account temperature of human body and floor surface.

This paper presents the numerical results of particle propagation in open space, taking into account the temperature of the human body and the surface of the ground. And also, the settling of particles or droplets under the action of gravitational force and transport in the open air is taken into account, taking into account the temperature during the process of breathing and sneezing or coughing. The temperature of the body and the surface of the ground, different rates of particle emission from the mouth, such as breathing and coughing or sneezing, are numerically investigated. The effect of temperature, cross-inlet wind, and the velocity of particle ejection from a person's mouth on social distancing is being investigated using a numerical calculation. The variable temperature of the human body forms a thermal plume, which affects the increase in the trajectory of the particle propagation, taking into account the lateral air flow. The thermal plume affects the particles in the breathing zone and spreads the particles over long distances in the direction of the airflow. The result of this work shows that in open space, taking into account the temperature of the body and the surface of the ground, a 2-m social distance may be insufficient for the process of sneezing and social distance must be observed depending on the breathing mode.

On-line monitoring of flow process in a spout-fluid bed by combining electrical tomography and high-speed CCD camera

To investigate spouted flow characteristics in a rectangular spout-fluid bed with bafflers, a non-intrusive measurement approach, which combines electrical capacitance tomography (ECT), pressure measurements and high-speed CCD imaging technology, is proposed. The ECT sensor has 12 electrodes on the external wall and 12 electrodes inside, forming three imaging regions with 8 electrodes in each region. The flow hydrodynamic characteristics in the spouted bed e.g., pressure fluctuation, particle packing fraction and fountain form, are investigated. The frequency domain of pressure and particle packing fraction signals as well as ECT images indicate that the flow regime in the jet region transits from slugging to spouting in fountain formation process, and when the fluidization velocity in one side increases, the flow regime in the same region transits into slugging bed. The spouting pressure drop is affected by the fluidization condition in the side region, and the high characteristic frequency of pressure signal decreases when the side region condition changes from blockage to fluidization. The fountain height increases linearly with the superficial gas velocity. When the gas velocity is high, the fountain tends to be offset by the influence of the lateral airflow which is caused by the imbalance of the air pressure on two side regions.

Experimental study on the effect of plasma excitation on the atomization characteristics of aviation kerosene transverse jet

In order to explore the critical technology of plasma application to assist fuel atomization, a jet discharge plasma excitation atomization device was independently designed. And the test of fuel atomization characteristics were carried out. The effects of Ar volumetric flow and peak voltage on Sauter mean diameter (SMD) and penetration depth were investigated. The experimental results show that the introduction of plasma can significantly improve atomization characteristics. The introduction of plasma has significantly improved the atomization characteristics, and the SMD is reduced by 6.31%–31.91%. Plasma-assisted regulation can be achieved by changing the peak voltage and Ar volumetric flow. Ar jet plasma excitation inhibits the penetration of single-hole fuel jets in lateral airflow. The regulation of the longitudinal upper and lower boundaries of the single-hole fuel jet can be achieved by changing the peak voltage and Ar volumetric flow. Compared with the traditional atomization device, the new plasma excitation atomization device can produce a better atomization effect. The better the atomization effect, the more thoroughly the fuel particles can be mixed with the air, which can not only considerably shorten the combustion time, but also the more complete the combustion. In addition, it can promote energy saving and emission reduction and prolong the engine’s life. In general, the new plasma atomization device provides a new idea for the future direction of atomization.

Experimental study on spray characteristics of fan nozzle for integrated afterburner in lateral airflow

The spatial distribution of fuel and high atomization quality plays a vital role in combustion performance enhancement for integrated afterburners. This study is based on integrated strut stabilizers using aviation kerosene (RP-3) as the atomizing medium. Specifically, the spray distribution characteristics of the fan nozzle were studied at ambient temperature and pressure, lateral airflow velocities within the range of 5–30 m/s, and a fuel supply pressure difference between 0.2 and 1.2 MPa. Macroscopic and microscopic spray characteristics were studied by high-speed photography method, Spraymaster, and ParticleMaster system respectively. The results show that mean droplet diameters decreased with an increasing lateral airflow velocity and a decreasing fuel supply pressure difference. The recirculation zone at the back of the struts will have an entrainment effect on the downstream of the spray, making part of the spray bend toward the recirculation zone. The results of the spray organization of a fan nozzle in this study can be used to support the design of new integrated afterburners.

Experimental investigations on aviation kerosene Multi-jets in high temperature and low pressure air crossflow

There are the key factors affecting the combustion performance of the burner, including the jet trajectory, fragmentation and evaporation process of fuel jet in air crossflow and the uniform characteristics of fuel-gas mixing. In our experimental investigation, we studied the effects of liquid/air momentum flux ratio, the number of radial and axial injection points on jet trajectory, penetration depth and Sauter mean diameter (SMD) distribution of aviation kerosene injected into high temperature and low pressure air crossflow. Specifically, the pressure of air crossflow was set to 0.06–0.09Mpa, the speed 0.1 Ma, and the temperature 500 K. The jet trajectories of aviation kerosene were captured using a triggered image sensor (CCD) camera; the SMD of the aviation kerosene along the flow direction was measured using a Malvern laser particle sizer. The main observation results are: (1) The liquid/air momentum flux ratio is still the main factor affecting the penetration depth of liquid jet, fitting the dimensionless formula of jet trajectories of aviation kerosene injected into high temperature and low pressure lateral airflow. The fitting formula of single injection point and multiple injection points is y/d=0.4357q0.8384x/d0.4797 and y/d=0.513q0.8869x/d0.3661 respectively. (2) When the air crossflow pressure goes down, it will reduce the aerodynamic Weber number and increase the penetration depth, while it will reduce the Reynolds number of jet liquid and increase the average droplet size. For every 0.01Mpa decrease in air crossflow pressure, the aviation kerosene particle size SMD increases by 5–20 µm. (3) When the number of radial jet points goes up, it will enhance the interaction between CVP (Counter Rotating Vortex Pairs) and complex vortex system between multiple jets, which leads to rising growth rate of jet liquid column surface wave and the premature break-up, reducing the penetration depth by 15–25 mm; Compared with the single injection point, the influence of liquid/air momentum flux ratio on the jet trajectory and penetration depth of the multi-injection point becomes smaller, and the difference is more obvious under the condition of high liquid/air momentum flux ratio.

Correlation of Rhinomanometry Measurement and True Lateral Radiography towards the Degree of Upper Airway Obstruction in Patients with Adenoid Hypertrophy

Background: Adenoid hypertrophy is one of the most common disorders in children which may lead to upper airway obstruction. Various modalities to measure airway obstruction in patients with adenoid hypertrophy, including true lateral radiographs, nasoendoscopy, and rhinomanometry are available; however, the results from different studies are still controversial. This study aimed to determine the relationship between the results of rhinomanometry and the true lateral radiographs to the degree of upper airway obstruction in patients with adenoid hypertrophy. Methods: This cross-sectional study included a total of 33 patients with adenoid hypertrophy aged 5-18 years using a purposive sampling technique. Patients diagnosed with adenoid hypertrophy were subjected to a true lateral examination using lateral neck radiographs to measure the degree of airway obstruction. Subsequently, an active anterior rhinomanometry was performed by measuring resistance and nasal airflow and then measuring the degree of airway obstruction. Data analysis was done using Chi-Square test. Results: The rhinomanometric nasal resistance in the inspiratory phase was 0.4159 ± 0.15201 Pa/cm3/s and 0.3694 ± 0.13717 Pa/cm3/s in the expiration phase. The results showed a significant relationship between the true lateral radiographs and both nasal inspiratory (p=0.005) and expiratory resistance (p=0.004). Similarly, the relationship between the true lateral radiographs and nasal airflow on both inspiratory and expiratory rhinomanometry was significant (p<0.05). Conclusion: Rhinomanometric measurements can be used as an additional objective examination in assessing the degree of upper airway obstruction in patients with adenoid hypertrophy prior to surgery.

The effect of a lateral airflow created on nozzle tip on the spray droplets deposition

The effect of a lateral airflow created on nozzle tip on the spray droplets deposition

Flow analysis of a front opening unified pod (FOUP) subjected to different fan filter unit (FFU) coverage area in mini-environment

Moisture contamination control has been adopted in many wafer handling and storage processes. In portable wafer carriers called front opening unified pods (FOUPs), the current industry-accepted methods of moisture control are gas purging and laminar air curtain (LAC). Both typically use purified clean dry air (CDA). In this study, we investigated five different methods of FOUP moisture control: conventional and diffuser-based purging, LAC, and combinations of each purging method with LAC. Two different scenarios of 100% and 75% FFU coverage area were examined. The FOUP was empty and its internal volume was exposed to a mock-up mini-environment (ME)–a process confinement device used in semiconductor fabs. Also, the LAC was mounted inside the ME above the FOUP opening. Smoke flow visualization, particle image velocimetry (PIV) and humidity measurement were performed in the FOUP median plane. Streamline flow patterns were obtained from the PIV results that can significantly enhance the evaluation of the moisture removal performance of different case studies. The findings showed that the combination of diffuser purge and LAC was the most resistant against external lateral moist air flow wherein it yielded the lowest average humidity. The findings could be beneficial for reducing waste and increasing product quality in semiconductor manufacturing. This can lead to significant reductions in energy usage and drastically reduce manufacturing costs.

Heat transfer enhancement in mini channel heat sinks utilizing corona wind: A numerical study

A full-scale three-dimensional model of a rectangular channel mini heat sink is developed to numerically investigate the feasibility of heat transfer enhancement utilizing an external electric field. Heat transfer mechanism in the presence of corona wind induced by a wire electrode and its favorable impact on the hydrodynamic and thermal characteristics of working fluid coolant are elaborately discussed. Effects of various parameters such as number of electrodes, electrode radius, electrode location, and electrode-flow configuration as well as the external applied voltage and Reynolds number on heat transfer enhancement are investigated. This study indicates that the electric field creates a vortex which in turn causes flow mixing in the vicinity of the heated surface, disturbs the thermal boundary layer and consequently increases the heat transfer rate. Results show that heat transfer enhancement is directly and inversely proportional to the voltage and Reynolds number, respectively. Furthermore, it is indicated that increasing the number of electrodes leads to a significant reduction in the heat transfer rate unfavorably impacting the heat transfer enhancement. It is attributed to the simultaneous interaction between the adjacent induced vortices. Eventually, it is shown that perpendicular configuration of the flow-electrode layout performs better than its parallel counterpart where an induced lateral air flow reduces the heat transfer augmentation. A maximum heat transfer enhancement of 439% compared to that of without any electrical field case is achieved by using a single electrode in the perpendicular electrode-flow layout.

Three-dimensional numerical research on the effects of lateral pulsating airflow on droplet breakup

A three-dimensional physical and mathematical model of the lateral airflow for droplet breakup was established. Numerical simulation was used to study the impact of the pulsating airflow on the droplet breakup process and analyze the variation in deformation rate under different amplitudes and frequencies. The results show that compared with uniform airflow, pulsating airflow can enhance the effect of droplet breakup, with an optimal droplet crushing effect occurring when the relative amplitude of the pulsating airflow was A = 1 and the Womersley number of the pulsating airflow was 96.6.

Forced Convection Heat Transfer from a Flat Plate between Array with Lateral Air Flow.(Dept.M)

An experimental work on heat transfer by forced convection was conducted in order to study the heat transfer from hot rectangular tlat p late (155 x 115 mm) to an air stream. The hot place was situated between unheated p laces array at various locations in the flow direction. The air flow stream enters the tunnel ducc laterally from one side and from two sides. The study was mainly concerned with the effect of the lateral air flow on the average film coefficient of heat transfer . An exp erimental test rig was designed and constructed for chis investigation. The experiments covered the place locations of x = 12.5, 22.5, 32.5, 42.5 and 62.5 mm. and extended over a range of Reynolds number from about 6,800 to 109.000. Two correlations between the average Nusselt numoer and the Reynolds umbes were deduced, one was for the case of air entering the tunnel duct laterally from one side and the other was for the case of air entering the duco from two sides. The exp eriments were performed for the case of uniform heat flux. A comparison with the available work in the literature review was also made.

Experimental characterization and real-time monitoring for laser percussion drilling in titanium alloy using transverse electric field assistance and/or lateral air blowing

A novel laser percussion drilling technology assisted by an electric field with lateral air blowing is reported. The lateral air blowing is first proposed for assisting the E-field assisted laser drilling for improving hole-drilling performance, quality and efficiency by blowing away the vapor plume and cooling the target workpiece. A high-speed camera is first used for observing and characterizing the transient laser percussion drilling process with and without an electric field and/or a lateral airflow. It was indicated that the transverse electric force and/or the side air blowing expedited the spatial motion with dispersion and density reduction of the vapor-plasma plume for enhancing laser drilling efficiency via weakening the plume-induced shield effect. The recast layer was reduced by using the transverse E-field assistance with and without lateral air blowing, and the combined assistance of a transverse E-field together with a lateral airflow was more effective for reducing the recast layer. Interestingly, as a result of the dynamic air cover across the sample surface induced by the lateral air blowing, the laser-vapor interaction inside a drilling hole was greatly enhanced together with the laser-material interaction, leading to the rapidly-accumulated expansion and then the sudden explosion of the laser-induced plume inside a drilling hole. The enhanced vertical scouring and flowing effect resulting from the accelerated vertical plume-motion inside a drilling hole, which was caused by the accumulated pressure difference inside and outside of the hole due to the enhanced outside motion-dispersion effect (especially induced by the electric force) of the plasma-vapor plume, expedited the uniform molten material removal and distribution along the hole sidewall. Importantly, a transverse E-field with and without a side airflow effectively refined the grains of the heat affected zone (HAZ) near the fusion zone of a through hole via increasing the average grain size number. The micro hardness was improved after laser hole-drilling by loading a transverse E-field with and without a side airflow due to a grain refinement effect with and without an airflow cooling effect. It was demonstrated that the lateral air blowing used was more effective to increase laser drilling efficiency for drilling through the workpiece than the E-field used, and the hole-drilling efficiency was further increased if using the combined assistance of a transverse E-field and a side airflow. After the workpiece was drilled through, the hybrid plume signal was effectively suppressed primarily above the hole entrance by using a transverse E-field and/or a side airflow, especially in case of using the transverse E-field assistance.

A Study on the Drift of Spray Droplets Dipped in Airflows with Different Directions

The European Directive concerning pesticide sustainable use establishes regulations to reduce the environmental drift throughout treatments to agricultural crops, particularly in nearby sensitive areas, such as water bodies, natural reserves and urban areas. The drift represents the fraction of mixture delivered by the sprayer that is not caught by the crop, and is the clearest cause of environmental pollution. Anti-drift nozzles are usually employed, and buffer zones are also maintained along the edges of the sprayed field to reduce drift production. The aim of this work was the theoretical study of the motion of the spray droplets delivered by a nozzle, dipped in downwards and/or lateral forced air flows. A mathematical model has been developed, consisting of a system of 2nd order differential equations, to simulate the motion of water droplets of different diameters within simultaneous different directions of air flow. The graphs, obtained by means of the numerical solution of the model, allow us to analyze the level of the droplets’ drift, according to their diameter and to the speed of the lateral and the downward air flows, respectively. A lateral airflow at a speed of 5 m · s − 1 produced a drift in its direction until 1.70 m for droplets from 100 to 500 μm in diameter. For larger drops, the impact of the downward airflow is not very significant. The results obtained by the numerical solution of the mathematical model have been compared with the results of experimental tests carried out to evaluate the drift of spray produced by different nozzles.

Biomimetic smoking robot for in vitro inhalation exposure compatible with microfluidic organ chips.

Exposure of lung tissues to cigarette smoke is a major cause of human disease and death worldwide. Unfortunately, adequate model systems that can reliably recapitulate disease biogenesis in vitro, including exposure of the human lung airway to fresh whole cigarette smoke (WCS) under physiological breathing airflow, are lacking. This protocol extension builds upon, and can be used with, our earlier protocol for microfabrication of human organs-on-chips. Here, we describe the engineering, assembly and operation of a microfluidically coupled, multi-compartment platform that bidirectionally 'breathes' WCS through microchannels of a human lung small airway microfluidic culture device, mimicking how lung cells may experience smoke in vivo. Several WCS-exposure systems have been developed, but they introduce smoke directly from above the cell cultures, rather than tangentially as naturally occurs in the lung due to lateral airflow. We detail the development of an organ chip-compatible microrespirator and a smoke machine to simulate breathing behavior and smoking topography parameters such as puff time, inter-puff interval and puffs per cigarette. Detailed design files, assembly instructions and control software are provided. This novel platform can be fabricated and assembled in days and can be used repeatedly. Moderate to advanced engineering and programming skills are required to successfully implement this protocol. When coupled with the small airway chip, this protocol can enable prediction of patient-specific biological responses in a matched-comparative manner. We also demonstrate how to adapt the protocol to expose living ciliated airway epithelial cells to smoke generated by electronic cigarettes (e-cigarettes) on-chip.

An articulatory study of the alveolar versus retroflex contrast in pre- and post-stress position in Arrernte

This study presents articulometry and palatography data for Arrernte, a language of Central Australia. It examines the contrast between the apical consonants – alveolar versus retroflex – according to lexical stress. Stop, nasal and lateral consonants are treated separately. Results show that the most prototypical retroflex articulation – where the tongue tip is retracted for post-alveolar closure and eventually released at a more anterior location – occurs after a stressed vowel. By contrast, a prototypical alveolar articulation – with closure and release at the same (anterior) region along the palate – is more likely to occur before a stressed vowel. In addition, it is shown that the contrast between alveolars and retroflexes varies by manner of articulation, being clearest for the nasal manner. It is suggested that the low jaw position which is an inherent property of nasal articulations facilitates retraction of the tongue tip for retroflexion, and that nasalization of adjacent vowels may motivate an exaggeration of the alveolar-retroflex contrast. For laterals, however, the alveolar~retroflex contrast is not so clear, and it is suggested that the articulatory requirements for lateral airflow may compromise full retraction of the tongue tip. Typological implications of these results are discussed, as is the possibility that CV versus VC (i.e. alveolar versus retroflex) cues to place of articulation are best encoded within a stressed vowel.

Investigation on emergency core coolant bypass with local measurement of liquid film thickness using electrical conductance sensor fabricated on flexible printed circuit board

An experimental work was conducted in a reduced-scale downcomer annulus of a nuclear reactor pressure vessel in order to investigate the behavior of liquid films under emergency core coolant (ECC) bypass conditions and to obtain high definition data for validating two-phase flow prediction capability of computational fluid dynamics (CFD) codes. Air and water at ambient pressure and temperature were used as a working fluid, creating a multidimensional two-phase flow in the test section. The main instrumentation was an electrical conductance sensor that was developed to measure the local thickness of the liquid film. The sensor has an array of 24 × 24 measuring points, each of which has 12 mm × 6 mm of the sensing area. The fabrication of the electrodes on a flexible printed circuit board enabled the sensor to be installed on the curved surface. The time-averaged liquid film thickness, which was measured by the developed sensor, shows the influence of the lateral air flow on the liquid film flow, and it was compared with visual observations. As the air velocity increased, a droplet appeared that was created in the thick part of the liquid film, and the thinned liquid film after entrainment could be confirmed from the measured thickness distribution. In this study, qualitative and quantitative analyses of the measurement results show the reliability of the developed sensor and help to understand the liquid film behavior in the ECC bypass phenomenon. Furthermore, the measured thickness distribution can contribute to validating the CFD codes, which have not been validated sufficiently because of a lack of local measurement data for the ECC bypass condition.