scholarly journals Full-Size Experimental Assessment of the Aerodynamic Sealing of Low Velocity Air Curtains

Fluids ◽  
2021 ◽  
Vol 6 (10) ◽  
pp. 359
Author(s):  
João Carlos Godinho Viegas ◽  
Levi Carrasco ◽  
Luis Pinto ◽  
João Morais ◽  
Paulo Morais ◽  
...  
Keyword(s):  
Average Velocity ◽  
Research Work ◽  
Reynolds Numbers ◽  
Air Flow Rate ◽  
Low Velocity ◽  
Air Curtain ◽  
Full Size ◽  
Jet Nozzle ◽  
General Physical ◽  
Contaminant Transfer

Vertical air curtains are often used to separate two different zones to reduce contaminant transfer or even to provide aerodynamic sealing from one zone to the other. In this isothermal full-size experimental research work, the contaminant transfer between zones is reduced using an air extraction from the “contaminated” compartment and an air curtain. This work correlates the minimum exhaust air flow rate required to reach the aerodynamic sealing at the opening connecting two different zones with the jet nozzle velocity for small nozzle thicknesses (5 mm, 10 mm and 16 mm), particularly for Reynolds numbers below 3800. Following the experimental study, a general physical law that relates the jet parameters (angle, nozzle thickness and jet velocity at the nozzle) with the average velocity through the opening (for the condition of acceptable contaminant tightness) was obtained. The results showed that the average velocity of the flow across a door protected by an air curtain required to keep the aerodynamic sealing varies linearly with Re. The slope, however, is different below and above Re = 3820.

An Air Curtain Along a Wall With High Inlet Turbulence

2004 ◽  
Vol 126 (3) ◽  
pp. 391-398 ◽  
Author(s):  
Brandon S. Field ◽  
Eric Loth
Keyword(s):  
Ambient Air ◽  
Reynolds Numbers ◽  
Velocity Fields ◽  
Air Curtain ◽  
Image Velocimetry ◽  
Number Variation ◽  
Inflow Turbulence ◽  
High Turbulence ◽  
Isothermal Wall ◽  
Eddy Dynamics

A downward blowing isothermal wall jet at moderate Reynolds numbers (1,500 to 8,500) with significant inflow turbulence (ca. 6%) was investigated. The flow configuration is an idealization of the air curtains of refrigerated display cases. Flow visualization using particle seeding was employed to identify the flow field eddy dynamics. Particle Image Velocimetry was used to examine the velocity fields in terms of mean and fluctuating values. These diagnostics showed that the air curtain entrainment was dominated by a large variety of eddies that engulfed ambient air into the air curtain. The velocity fields generally showed linear spreading, significant deceleration and high turbulence levels (ca. 25%). It was observed that the air curtain dynamics, velocity fields and growth were not significantly sensitive to Reynolds number variation between Re=3,800 and Re=8,500. However, at low air velocities (Re=1,500), the curtain was found to detach, leading to a large air curtain thickness and high curtain entrainment.

Effects of Applied Acoustic Fields on Attached Jet Flows

1971 ◽  
Vol 93 (1) ◽  
pp. 63-73 ◽  
Author(s):  
Donald O. Rockwell ◽  
Kenji Toda
Keyword(s):  
Reynolds Numbers ◽  
Jet Flows ◽  
Design Criteria ◽  
Arc Length ◽  
Hot Wire ◽  
Applied Frequency ◽  
Smoke Visualization ◽  
The Third ◽  
Severe Effect ◽  
Jet Nozzle

The effects of application of sound of a spectrum of frequencies and amplitudes to bounded attached jets of a range of Reynolds numbers flowing over surfaces of various radii of curvature have been examined using hot-wire anemometry, smoke visualization, and tuft-deflection techniques. Frequencies of sound to which the jet is sensitive, results of changes in sound amplitude at a given frequency, and the growth of the effects of applied sound with arc length from the nozzle exit were investigated to provide some qualitative design criteria for controlling the sensitivity of flueric elements to externally applied sound. Frequencies of sound which are related to the jet nozzle resonance characteristics have the most severe effect on the attached jet. For a given applied frequency, the flow field of the jet can be altered for a much wider range of jet Reynolds number at higher amplitudes of applied sound than at relatively low amplitudes of applied sound. Four Reynolds numbers regimes can be established to describe the behavior of the attached jet with applied sound, Frequency- and amplitude-dependent jumps in angle of detachment of the jet are attainable in the first two regimes, and deflections of the jet proportional to the applied frequency and amplitude are attainable in the third and fourth regimes.

scholarly journals Wind Load Reduction in Hollow Panel Arrayed Set

2016 ◽  
Vol 2016 ◽  
pp. 1-14
Author(s):  
Michalina Markousi ◽  
Dimitrios K. Fytanidis ◽  
Johannes V. Soulis
Keyword(s):  
Research Work ◽  
Flow Analysis ◽  
Flow Region ◽  
Maximum Load ◽  
Wind Load ◽  
Wind Loading ◽  
Load Reduction ◽  
Low Velocity ◽  
Approach Angle ◽  
Surface Areas

Reducing the wind loading of photovoltaic structures is crucial for their structural stability. In this study, two solar panel arrayed sets were numerically tested for load reduction purposes. All panel surface areas of the arrayed set are exposed to the wind similarly. The first set was comprised of conventional panels. The second one was fitted with square holes located right at the gravity center of each panel. Wind flow analysis on standalone arrayed set of panels at fixed inclination was carried out to calculate the wind loads at various flow velocities and directions. The panels which included holes reduced the velocity in the downwind flow region and extended the low velocity flow region when compared to the nonhole panels. The loading reduction, in the arrayed set of panels with holes ranged from 0.8% to 12.53%. The maximum load reduction occurred at 6.0 m/s upwind velocity and 120.0° approach angle. At 30.00 approach angle, wind load increased but marginally. Current research work findings suggest that the panel holes greatly affect the flow pattern and subsequently the wind load reduction. The computational analysis indicates that it is possible to considerably reduce the wind loading using panels with holes.

scholarly journals Delineation of Weathered Layer Using Uphole and Surface Seismic Refraction Methods in Parts of Niger Delta, Nigeria

2021 ◽  
Vol 26 (1) ◽  
pp. 58-66
Author(s):  
Mfoniso Aka ◽  
Okechukwu Agbasi
Keyword(s):  
Niger Delta ◽  
Average Velocity ◽  
Seismic Refraction ◽  
Low Velocity ◽  
Engineering Structures ◽  
Experimental Proof ◽  
Seismic Surveys ◽  
Shot Point ◽  
Weathered Layer ◽  
Velocity Zone

Uphole and surface seismic refraction surveys were carried out in parts of the Niger Delta, Nigeria, to delineate weathering thickness and velocity associated with aweathered layer. A total of twelve uphole and surface seismic refraction surveyswere shot, computed and analyzed. The velocity of the uphole seismic refraction ranged from 344.8 to 680.3 m/s with a thickness of 5.45 to 13.35 m. Surface seismic refraction ranged from 326.6 to 670.2 m/s and 4.30 to 12.0 m, respectively. The average velocity and thickness ranged from 559.6 to 548.0 m/s and 9.43 to 8.63m with differences of 11.6 m/s and 0.83 m respectively. The VW/VS ratios ranged from 0.955 to 1.059. This indicates that the uphole velocity is higher than the surface refraction velocity leading to low VW/VS values. This is a direct experimental proof of a low velocity zone, confirming the weathered nature of the area. The results of both refraction methods are reliable; the differences in surface refraction values are due to shot point offsets. Based on these findings, it is recommended that shots for seismic surveys should be located above 15.0 m in the area to delineate the effects associated with weathered layers to ensure that will be competent to withstand engineering structures.  

scholarly journals Effect of the Reinforcement Phase on Indentation Resistance and Damage Characterization of Glass/Epoxy Laminates Using Acoustic Emission Monitoring

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
C. Suresh Kumar ◽  
K. Saravanakumar ◽  
P. Prathap ◽  
M. Prince ◽  
G. Bharathiraja ◽  
...  
Keyword(s):  
Acoustic Emission ◽  
Glass Fiber ◽  
Research Work ◽  
Low Velocity Impact ◽  
Low Velocity ◽  
Cumulative Energy ◽  
Static Indentation ◽  
Felicity Ratio ◽  
Woven Glass Fiber ◽  
Energy Absorbing

The effect of reinforcement phases on indentation resistance and damage behavior of glass/epoxy laminates was investigated in this research work. Woven glass fiber mat and nonwoven chopped glass fiber mat were used as fiber reinforcement phases for fabricating the laminates. Low-velocity impact and quasi-static indentation tests were performed on both laminates to investigate the contact behavior and energy-absorbing capability. Moreover, the acoustic emission (AE) technique was employed to monitor the indentation damage resistance. AE parameters including normalized cumulative counts (NCC), normalized cumulative energy (NCE), rise angle (RA), and felicity ratio (FR) were analyzed. The bidirectional laminates showed premature load drops and drastic changes in the normalized cumulative counts/energy profile in the beginning of loading cycles, indicating the development of macrodamage such as debonding/delamination. AE sentry function results of bidirectional laminates show longer PII function at the earlier stages, associated with minor PIII function and greater PIV function, indicating the continuous degradation and progression of damage. In contrast, the chopped laminates exhibited superior postimpact performance than the bidirectional laminates. The presence of randomly oriented fibres prevents the delamination crack propagation during compression loading, which was attributed with the increased residual compressive strength.

scholarly journals Numerical study of gas dynamics and heat transfer in matrix channels at various rib angles

2021 ◽  
Vol 2057 (1) ◽  
pp. 012026
Author(s):  
A V Barsukov ◽  
V V Terekhov ◽  
V I Terekhov
Keyword(s):  
Heat Transfer ◽  
Numerical Simulation ◽  
Reynolds Number ◽  
Gas Dynamics ◽  
Average Velocity ◽  
Numerical Study ◽  
Reynolds Numbers ◽  
Separation Flow ◽  
Maximum Heat ◽  
Maximum Heat Transfer

Abstract The results of numerical simulation of the separation flow in matrix channels by the RANS method are presented. The simulation is performed at the Reynolds number Re = 12600, determined by the mass-average velocity and the height of the channel. The distribution of the local Nusselt number is obtained for various Reynolds numbers in the range of 5÷15⋅103 and several rib angles. It is shown that the temperature distribution on the surface is highly nonuniform; in particular, the maximum heat transfer value is observed near the upper edge facets, in the vicinity of which the greatest velocity gradient is observed.

Detailed Flow Analysis Around Blade Tip With a Mie Vane in Case of Different Blade Aspect Ratios and Different Reynolds Numbers

2003 ◽  
Author(s):  
Yukimaru Shimizu ◽  
Edmond Ismaili ◽  
Yasunari Kamada ◽  
Takao Maeda
Keyword(s):  
Reynolds Number ◽  
Research Work ◽  
Flow Analysis ◽  
Reynolds Numbers ◽  
Power Coefficient ◽  
Work Related ◽  
Aspect Ratios ◽  
Power Increase ◽  
Lower Reynolds Number ◽  
Blade Tip

The results of an extensive experimental research work related to the performance of a HAWT with a tip-mounted Mie type vane are presented in this paper. From performance experiments carried out on four sets of blades with varying aspect ratios and for different Reynolds number, it was found that the application of a tip-mounted Mie vane resulted in a larger increase in maximum power coefficient for rotors with smaller aspect ratio and for lower Reynolds number. To investigate further the phenomenon and to explain the relationships found between power increase due to a Mie vane and blade aspect ratios and Reynolds number, detailed flow visualization around blade tip and the Mie vane were performed. It was found that the tendency of the power increase due to a Mie vane was dependent on the size of a corner vortex between blade tip and the downstream extension of the Mie vane.

Recent Research on Cascade-Flow Problems

1966 ◽  
Vol 88 (1) ◽  
pp. 221-228 ◽  
Author(s):  
H. Schlichting ◽  
A. Das
Keyword(s):  
Reynolds Number ◽  
Secondary Flow ◽  
High Speed ◽  
Research Work ◽  
Reynolds Numbers ◽  
Tip Clearance ◽  
Flow Problems ◽  
Flow Losses ◽  
Cascade Flow ◽  
Wide Range

A survey is given of extensive research work on cascade-flow problems carried out in recent years in Germany. A considerable part of this work was done in the Variable Density High Speed Cascade Wind Tunnel of the Deutsche Forschungsanstalt fu¨r Luftfahrt at Braunschweig, in which the Reynolds number and the Mach number of the cascade can be varied independently. For compressor cascades with blades of different thickness ratio extensive measurements of the aerodynamic coefficients have been carried out in a wide range of Mach numbers and Reynolds numbers. For very low Reynolds numbers, as they occur for jet engines in high-altitude flight, the influence of turbulence level on loss coefficients has been investigated. Furthermore, comprehensive investigations on secondary-flow losses are reported. The most important parameters in this connection are the ratio of blade length to blade chord, the tip clearance, the Reynolds number, and the deflection of the flow in the cascade. The influence of all these parameters on the secondary-flow losses has been clarified to a certain extent.

AIR CURTAIN INCINERATOR TESTS

1983 ◽  
Vol 1983 (1) ◽  
pp. 33-38
Author(s):  
Keith F. Kruk
Keyword(s):  
Flow Rate ◽  
Air Flow ◽  
Test System ◽  
Design Criteria ◽  
Front Wall ◽  
Water Spray ◽  
Air Flow Rate ◽  
Air Curtain ◽  
Operating Variables ◽  
Combustion Tests

ABSTRACT The use of an curtain incinerator to dispose of materials recovered from an oil spill was investigated for the Alaskan Beaufort Sea Oilspill Response Body (ABSORB). A series of combustion experiments was conducted in a prototype incinerator 10 feet wide by 10 feet long by 14 feet high. Combustion rates, emissions, and temperatures were monitored during the experiments. Operating variables investigated included air flow rate, direction of air into the combustion chamber, waste feed rate, water spray over the combustion zone, and the slant of the combustion chamber's front wall. Some of the major results were:Optimum air flow rate into the incinerator is 7,000 cubic feet per minute.The system performed satisfactorily at combustion rates exceeding 600 barrels per day.At 600 bbl/day, most emulsions burned with emissions less than 1 Ringelmann.Oil with 20-to-30 percent water burned most efficiently.Oil-saturated straw was consistently burned in the incinerator at measured emission levels of less than 1 Ringelmann.Combustion temperatures in the incinerator will exceed 2,000°F with an 18,500-Btu-per-pound oil. Included in this paper are details of the test system, results of combustion tests, and recommended design criteria for an arctic system.

On a Circular Cylinder in a Uniform Planar Shear Flow at Subcritical Reynolds Number

2002 ◽  
Author(s):  
D. Sumner ◽  
O. O. Akosile
Keyword(s):  
Reynolds Number ◽  
Circular Cylinder ◽  
Shear Flow ◽  
Lift Force ◽  
Experimental Studies ◽  
Reynolds Numbers ◽  
Low Velocity ◽  
Static Pressure Distribution ◽  
Planar Shear ◽  
The Mean

An experimental investigation was conducted of a circular cylinder immersed in a uniform planar shear flow, where the approach velocity varies across the diameter of the cylinder. The study was motivated by some apparent discrepancies between numerical and experimental studies of the flow, and the general lack of experimental data, particularly in the subcritical Reynolds number regime. Of interest was the direction and origin of the steady mean lift force experienced by the cylinder, which has been the subject of contradictory results in the literature, and for which measurements have rarely been reported. The circular cylinder was tested at Reynolds numbers from Re = 4.0×104 − 9.0×104, and the dimensionless shear parameter ranged from K = 0.02 − 0.07, which corresponded to a flow with low to moderate shear. The results showed that low to moderate shear has no appreciable influence on the Strouhal number, but has the effect of lowering the mean drag coefficient. The circular cylinder develops a small steady mean lift force directed towards the low-velocity side, which is attributed to an asymmetric mean static pressure distribution on its surface. The reduction in the mean drag force, however, cannot be attributed solely to this asymmetry.

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