Lateral Air Research Articles

Airflow characteristics within a slot-ventilated enclosure

The objective of this study is to numerically and experimentally investigate velocity characteristics throughout a long slot-ventilated enclosure as a function of inlet flow arrangement located on the same side of the exit section. This study focused on the effect of the enclosure’s confinement on the airflow pattern and more particularly on the wall jet characteristics concerning its decay and its stabilisation. An original approach is also proposed to evaluate the local effect of airflow pattern on ventilation efficiency. To improve the performance and the uniformity of ventilation in the enclosure, a new configuration with a lateral air inlet section was studied. The results concerning airflow characteristics and air-ventilation efficiency were compared and contrasted with the more common case with a central inlet section. A numerical approach based on computational fluid dynamics (CFD) Fluent code was used to test various turbulence closure models including the high and low Reynolds number form of the two-equation k– ε model and the more advanced Reynolds stress model (RSM). Comparisons with experimental data obtained on a scale model under isothermal conditions allow a critical evaluation of the performance of these models in internal flows.

Anode attachment of torch plasma arc with high-speed lateral gas air and axial plasma gas argon

Torch plasma arcs have useful high-energy and high-current characteristics. Torch plasma arcs can be flexible even if exposed to high-speed laterally flowing gases. This study measured the length, voltage, input power, heat power and heat efficiency of a torch plasma arc to the anode to elucidate their influence upon the plasma torch arc anode attachment with a high-velocity laterally flowing gas. That velocity was varied from 0 to 60 m s−1. The axial plasma gas argon flow rates used were 4, 8 and 12 slpm. Consequently, the input power increased about 8000–16 000 W with these lateral gas air velocities. The heat efficiency decreased with lateral gas air velocity from about 50% to 25% at a current of I = 150 A. The torch plasma arc length, La, was ca 1 cm. The results of this study are applicable for providing electrical power from the ground to high-speed vehicles or vice versa and for reducing anode erosion by anode spot movement.

Spontaneous otogenic intracerebral pneumocephalus: case report and review of the literature

Pneumocephalus is commonly associated with head and facial trauma, ear infection or surgical interventions. We describe the rare case of a spontaneous pneumocephalus arising from lateral mastoid air cells. A 48-year-old man presented with a 10-day history of sudden, repetitive, 'hammering-like' acoustic sensations in his left ear that were followed by word-finding difficulties and loss of vision in the right visual field. Imaging revealed a large, left temporal pneumatocele associated with a small acute intracerebral hemorrhage. Left temporal and subtemporal craniotomy and decompression were performed. Further exploration confirmed a dural and osseous defect in the anterolateral surface of the mastoid that was consecutively closed watertight. Although extremely rare, a spontaneous pneumocephalus with mastoidal origin should be considered as a possible diagnosis in patients with suggestive acoustic phenomena and other non-specific neurological symptoms.

An Endoscopic Study of the Greater Palatine Nerve

Using an endoscopic approach, lateral sphenoid air cells and terminal branches of the internal maxillary artery often can be accessed through the pterygomaxillary fossa: however, injury to the greater palatine nerve (GPN) can occur if the anatomy of this region is not understood clearly. This study was undertaken to define the pathway of the GPN and to identify landmarks useful in preventing its injury. Six cadaveric heads were used to endoscopically dissect and examine 11 pterygomaxillary fossae. An additional latex-injected cadaveric head was sectioned coronally and dissected bilaterally. The relationships between the vascular, neurological and bony structures and foramena were noted and described. All specimens studied maintained consistent relationships. The sphenopalatine and posterior nasal arteries cross nearly perpendicular and just superficial to the GPN. The GPN traveled anteriorly and inferiorly to reach the greater palatine foramen. The lateral wall of the canal ranged from a thin bony covering to complete dehiscence and was thinnest as it crossed the inferior turbinate and approached the foramen. The foramen rotundum was located lateral and superior to the sphenopalatine foramen near the roof of the maxillary sinus. When surgically approaching the pterygomaxillary fossa, injury to the GPN is avoidable by thorough knowledge of anatomy and awareness of the described landmarks.

Three-dimensional flame propagation above liquid fuel pools

Ignition and flame spread above liquid fuels initially below the flashpoint temperature are studied. Opposed air flow to the flame spread due to forced and/or natural convection is considered. Unsteady computations are performed in order to study the ignition event and to describe both uniform and pulsating flame spread. Pools of finite width and length are studied in air channels of prescribed height and width, thereby requiring a three-dimensional space resolution in order to capture the effects at the edge of the pool and at the side walls of the air channel. The effects of variations in surface tension due to surface temperature variations and of buoyancy in both the liquid and gas phases are considered. One-step chemical kinetics, Fickian diffusion, Fourier heat conduction, and laminar flow with variable properties are considered. Boundary layers at the walls and at the liquid/gas interface are resolved. A moving mesh scheme is employed to follow the flame motion. Regions of pulsation are found at both 1 g and 0 g. Average flame speed and pulsation frequency increase with initial fuel temperature. Surface tension can have a major effect, e.g., cause a recirculation. Buoyancy can modify flame speed and flame shape. The flame extends over the edge of the pool producing some clearly three-dimensional effects, such as lateral air motion. The computations are intended to guide and to explain experiments that are being performed at NASA Glenn by H. Ross and F. Miller.

The Southern Ocean Limb of the Global Deep Overturning Circulation*

Nine hydrographic sections are combined in an inverse box model of the Southern Ocean south of ∼12°S. The inclusion of independent diapycnal flux unknowns for each property and air–sea (heat, freshwater, and momentum) fluxes make it possible to estimate the three-dimensional deep water circulation. The authors find a vigorous 50 × 106 m3 s−1 deep overturning circulation that is dominated by an equatorward flow of Lower Circumpolar Deep Water and Antarctic Bottom Water and poleward flow of upper deep water including Indian and Pacific Deep Water below 1500 dbar. In the subtropical Indian and Pacific Oceans the deep overturning cell is essentially isolated from the thermocline and intermediate waters of the subtropical gyre. The southward flowing upper deep water shoals south of the Antarctic Circumpolar Current, where air–sea fluxes convert outcropping upper deep water to Antarctic surface water and drive a net air–sea transformation of 34 × 106 m3 s−1 to lighter intermediate water. It is the outcropping of upper deep water and transformation by air–sea fluxes that connects the deep and intermediate circulation cells. The significant poleward transport of relatively light (i.e., above all topography at the latitude of Drake Passage) upper deep water, as required here to balance lateral and diapycnal divergence and air–sea exchange, provides observational evidence that advection by standing and transient eddies carries significant meridional transport in the Southern Ocean.

Use of bone wax in the prevention of cerebrospinal fluid fistula in acoustic neuroma surgery.

Use of bone wax in the prevention of cerebrospinal fluid fistula in acoustic neuroma surgery.

"Pneumofornix" (Air Under the Eyelid): A Normal Finding

Normal pockets of air under the eyelids have not been previously described in the literature. To assess the incidence and patterns of normal air bubbles in the region of the eyelid, computed tomography (CT) scans of 126 normal orbits and 36 orbits of patients with thyroid orbitopathy were assessed. Twenty-eight (22%) of the normal orbits and 14 (39%) of the thyroid orbits had a well-defined medial or lateral air bubble (or both) on axial views (.1 > P > .05). Oval central or paracentral air bubbles in sections through the superior or inferior fornix were seen in 19 (15%) of the normal orbits and 10 (28%) of the thyroid orbits (.1 > P > .05). It is important to be aware of the incidence and patterns of these normal air bubbles to ensure their accurate differentiation from pathologic air bubbles.

Running characteristics of the magnetically levitated train in a curved track section

A three-dimensional running simulation program of the train motion which includes both electromagnetic and mechanical systems has been developed. For verification of running stability, the motion of the Maglev train with four bogies and three cars running into the curved section was calculated. Because the spring strength of the secondary suspension between bogies and cabins was much smaller than that of the electrodynamic suspension, interaction among bogies was small. The lateral displacement reached 0.045 m, which is about 50% of the lateral air gap. Therefore, the train can run without touching the wall of the guideway. As this lateral air gap caused roll torque, total roll angle of the bogie became 12.5% larger than the cant angle of the curved section.

Hydrodynamics of a circulating fluidized bed operated with different secondary air injection devices

A cold model of a circulating fluidized bed combustor having a 0.120 m i.d. and 5.75 m high riser, was operated by splitting the total gas flow rate in a primary air stream fed through the bottom distributor and a secondary air stream laterally injected at a fixed level along the riser. Two different feeding devices were used: in one case the injection of secondary air stream occurred over the whole circumference of the riser through a slot; in the other the injection occurred through four opposite ports. Solids used were 89 μm Ballotini. Overall superficial gas velocity was fixed at 6 m/s. Solids mass flux was alternatively equal to 35 and 55 kg/(s m 2). The ratio between secondary and primary air flow rates was kept at a value of 1. An isokinetic probe was used to measure radial profiles of upward and downward solids mass fluxes and those of tracer gas concentration. A stream of CO 2 was mixed with the secondary air stream before the injection and used as tracer gas. For each set of operating conditions, axial profile of voidage and radial profiles of solids mass flux and CO 2 concentration were measured along the riser. Results confirm that lateral air stream remarkably affects the hydrodynamics in the regions below and above the gas inlet. They also show that the mechanism of interaction between the secondary air stream and the gas-solids suspension rising from the primary zone completely changed when the injection device was changed. Solids and tracer gas distribution along the riser were noticeably different.

Objective Evaluation of Surface Characteristics to Determine Smoothness of Pile Fabrics

Abstract Measurements of surface characteristics of pile fabrics by various methods to determine surface smoothness is reported. It is demonstrated that the number of peaks detected by methods using a roller, stylus, and friction traces is the best indicator of fabric smoothness. A negative correlation between this quantity and smoothness suggests that fabrics that yield more peaks are likely to be smoother than those with fewer peaks. This also agrees broadly with the results of friction measurement, lateral air flow, and microscopic measurements. Subjectively, judges found fabrics readily identifiable, but finding the right descriptive adjective for these differences remains a problem.

Sound-insulating and sound-damping composite structure

A composite structure with sound-insulating and sound-damping effects for use on the interior surfaces of motor vehicles, comprising at least two groups of coatings resting loosely on one another. In particular, the first group consists of a bottom part (2) free to vibrate and provided with coatings (6) or a finish like that used in modern motor vehicle construction. Preferably the applied second group of coatings consists of an insulating coating (8, 9). This insulating coating can be provided with an additional protective layer (7) and/or a textile or textile-like decorative layer (5). According to the invention, insulating coating (8, 9) exhibits anisotropic air flow resistance. This is achieved in simple fashion by a carrier layer (9) with a geometric structure and a plurality of support 15 elements (13). These support elements (13) are formed essentially of narrow ribs and are arranged to form a complex cavity labyrinth in conjunction with the first group of coatings and thus permit lateral air flow with low flow resistance.

MRI of esthesioneuroblastoma.

Esthesioneuroblastomas are uncommon tumors originating in the olfactory epithelium of the superior nasal cavity. Accurate staging appropriately guides therapy and predicts survival. The MR appearance and pattern of contrast enhancement in these tumors have not been well described. The goals of this article were to analyze the MRI characteristics of esthesioneuroblastoma, including extent of tumor, differentiation from obstructive sinus disease, MR signal, and pattern of contrast enhancement. The MR examinations of six patients with proven advanced esthesioneuroblastoma were reviewed. Standard SE T1- and T2-weighted axial images were obtained [550-600/15-25 and 2,000-2,760/80-90 (TR/TE), respectively], followed by postcontrast axial and coronal T1-weighted sequences in all patients. Five of the six tumors were centered in the superior nasal cavity and one was centered in the lateral ethmoid air cells. Five tumors extended intracranially. Postobstructive sinus disease was always encountered. As compared to gray matter, the signal on T1-weighted images was either hypo- or isointense. On T2-weighted images, the signal varied from iso- to hyperintensity. Contrast enhancement was intense and of variable uniformity. Magnetic resonance signal characteristics helped to distinguish obstructive sinus disease from tumor. The MR signal characteristics and pattern of contrast enhancement were nonspecific for esthesioneuroblastoma. Enhanced images, particularly in the coronal plane, were very helpful in identifying intracranial extension.

Lateral air pressure distribution within vibrating particle beds

Measurements were made of the air pressure beneath, along one side of and within vibrating particle beds. Experiments were conducted using two different size ranges of glass beads (99 and 227 μm in mean diameter) with two bed heights, 100 and 120 mm. The lateral air pressure distribution was found to be fairly uniform near the bottom of the bed for all the particle beds tested. However, in beds of small particles, the difference in the magnitude between the peak air pressure on a vessel wall and those at other lateral positions (at a given depth) increased with decreasing bed depth, and passed through a maximum at a certain depth in the upper half region of the bed. In beds of large particles the lateral air pressure distribution was fairly uniform throughout the bed, although humps appeared in the pressure profile due to the collision between large particles and a small sensor immersed within the bed. The hump, however, did not prevent us from discerning the relative magnitude of the peak air pressures at a given bed depth.

A two-chamber vacuum cell for measuring the coefficient of permeability to air of the concrete cover on site

A new testing technique, suitable for on-site, non-destructive measurement of the permeability to air of the concrete cover is presented. The method is based upon applying a vacuum inside a cell placed on the concrete surface and on measuring the rate at which the pressure returns to the atmospheric value. Distinctive features of the method are a two-chamber cell and a regulator that balances the pressure in the inner (measuring) chamber and in the outer (quard-ring) chamber. Thus, unidirectional air flow into the inner chamber is achieved, eliminating any spurious lateral air flow. A simple model is proposed to calculate the coefficient of permeability and the depth affected by the test. Preliminary results fit very well to earlier measurements of the coefficient of permeability to oxygen by the Cembureau method.

Fuel Spray Motion in Air Flow.

In direct injection diesel engines the intense swirling air motion in the cylinder is useful for a higher air fuel mixing rate. Therefore, we have investigated fuel spray motion in air flow with a uniform velocity distribution in order to explain the effect of the air swirl on the fuel spray motion in the cylinders of direct injection diesel engines, and concluded that the spray movement affected by the lateral air motion is controlled by the momentum of the fuel injection, the momentum of the air motion, the effective diameter of the fuel injection nozzle and factors of air entrainment. Then, the equation of the fuel spray motion locus in lateral air flow is obtained.

Developments in Mass Flow Porometry

A ventilated leaf attachment clamp is described with which lateral air flow can be measured separately from through flow. Stomatal conductances are expressed with dimensions: mm s -1 . Based on parallel measurements with a diffusion porometer the relation between mass flow and diffusive flow conductances has been experimentally determined for three species. Records of stomatal movements in air of different compositions are presented

Appraisal of Woven Fabric Performance

This work evaluates the performance of 100% cotton woven fabrics. We have ex amined abrasion resistance, diverse mechanical properties (compression and flexion), and certain aesthetic properties (handle, i.e., stiffness, smoothness, and softness). Changes in the properties of a fabric as a consequence of wear are illustrated; wear is a laboratory action involving some method of abrasion such as an Accelerotor on either dry or damp fabrics. In addition, we consider some aspects of the physical and mechanical properties of woven fabrics in which changes in weight, thickness, stiffness, air permeability, and compression are used as criteria to assess damage caused by frictional abrasion. The results show that weight loss may be small as a result of short periods of accelerated wear, and changes in other physical properties may be large, particularly compression, flexion, and air permeability. The differences between worn and unworn fabrics can be detected subjectively by touch. Changes occur in fabric properties as a result of incremental wear. Weight per square meter, coercive couple, and flexural rigidity show consistent decreases with increasing abrasion time at a fairly uniform rate. Thickness, air permeability, lateral air permeability, and compression show inconsistent increases with increasing abrasion time at non-uniform rates.

A CASE HISTORY: CLEANUP OF A SUBSURFACE LEAK OF REFINED PRODUCT

ABSTRACT In October 1980, gasoline vapors were detected in two restaurants about 500 feet downgradient from the site of a bulk plant that handles refined products. A geohydrological investigation identified a plume of gasoline and diesel fuel floating on the water table from the bulk plant to the restaurant locations. The water table was encountered at a depth of 10 feet in alluvium composed of coarse gravels and cobbles. Pump tests of observation wells revealed the presence of buried, high permeability stream channels bordered by low permeability silty sediments. At low water level, a two-foot-thick layer of contaminated soil was observed above the product plume. Free product was removed by recovery wells downgradient of the bulk plant and each of the restaurants using a two-pump method. Produced water was reinjected upgradient into wells around the restaurants and via a trench at the bulk plant. Subsurface microbial biodegradation of residual hydrocarbons was stimulated by providing nutrients and diffused air at the water injection points. Biodegradation continued throughout a period of rising water table, reaching a high water depth above the contaminated soil layer. Accumulating fumes were removed from beneath one of the restaurants by means of a subsurface venting system constructed to maintain lateral air flow under the building. This paper relates the case history of discovery, investigation, and response to a groundwater contamination problem. The unique methods successfully used to cleanup a subsurface leak of refined product are described.

Optimization of Earth-Tube Heat Exchangers for Winter Ventilation of Swine Housing

ABSTRACT THE thermal and economic performance of both conventional and earth-tube ventilating systems for 10, 20, 30 and 40 sow farrowing houses were evaluated theoretically to optimize design recommendations. Thermal performance was simulated using finite difference techniques to obtain tubing outlet temperatures as a function of lateral length, tube diameter and air flow rate per tube. Optimal combinations of tube length and number of tubes were determined for several tube sizes for winter conditions using an economic analysis. For a 20-sow farrowing house having a 0.15 m diameter earth-tube system, the minimum equivalent annual cost of $483 was obtained with seven - 30 m long laterals having an air flow rate of 0.0357 mVs-tube. The winter fuel cost for this system was $263. Equivalent annual cost for a conventionally ventilated building was $611 with a fuel cost of $431. Other system designs providing substantial cost and energy savings were determined. As tubing diameter increased, optimal lateral lengths increased and the optimal number of laterals decreased.