scholarly journals Wind Dynamic Environment and Wind Tunnel Simulation Experiment of Bridge Sand Damage in Xierong Section of Lhasa–Linzhi Railway

2020 ◽  
Vol 12 (14) ◽  
pp. 5689 ◽  
Author(s):  
Shengbo Xie ◽  
Jianjun Qu ◽  
Qingjie Han ◽  
Yingjun Pang
Keyword(s):  
Wind Speed ◽  
Wind Tunnel ◽  
Prevention And Control ◽  
Simulation Experiment ◽  
Dynamic Environment ◽  
Windward Side ◽  
Sand Transport ◽  
Wind Tunnel Simulation ◽  
Drift Potential ◽  
And Control

The Lhasa–Linzhi Railway is located in the sandy area of the South Tibet valley, with high elevation and cold temperature. The Xierong section is a bridge section where blown sand hazards are severe. However, the disaster-causing mechanism of blown sand hazards in this section is currently unclear, thereby hindering targeted sand prevention and control. To address this problem, the wind dynamic environment of and causes of sand damage in this section are investigated through the field observation of the locale and a wind tunnel simulation experiment. Results show that the dominant sand-moving wind direction in the Xierong section is SSE. The wind speed, frequency of sand-moving wind, sand drift potential (DP), and maximum possible sand transport quantity (Q) in this section are relatively high during spring (March to May) and low during other seasons. The yearly resultant sand transport direction (RDD, RA) is SW. The angle between the route trend of this section and the sand transportation direction is 30°–45°, and the sand source is located in the east side of the railway. During spring, sand materials are blown up by the wind, forming blown sand flow and movement from the NE to SW direction. Increased wind speed area is formed between the top of the slope shoulder of the windward side of the bridge and the downwind direction of 3H, causing blown sand erosion. Meanwhile, weakened wind speed areas are formed within the distance of -3H at the upwind direction and from the downwind direction of the 3H to 20H of the bridge. These areas accumulate sand materials at the upwind and downwind directions of the bridge, thereby resulting in blown sand hazards. This research provides a scientific basis for the prevention and control of sand damage in the locale.

scholarly journals Investigation of the Superposition Effect of Oil Vapor Leakage and Diffusion from External Floating-Roof Tanks Using CFD Numerical Simulations and Wind-Tunnel Experiments

Processes ◽  
2020 ◽  
Vol 8 (3) ◽  
pp. 299
Author(s):  
Jie Fang ◽  
Weiqiu Huang ◽  
Fengyu Huang ◽  
Lipei Fu ◽  
Gao Zhang
Keyword(s):  
Wind Speed ◽  
Wind Tunnel ◽  
Simulation Method ◽  
Vapor Concentration ◽  
Monitoring And Control ◽  
Wind Tunnel Experiments ◽  
Ambient Wind ◽  
Wind Speeds ◽  
High Concentrations ◽  
And Control

Based on computational fluid dynamics (CFD) and Realizable k-ε turbulence model, we established a numerical simulation method for wind and vapor-concentration fields of various external floating-roof tanks (EFRTs) (single, two, and four) and verified its feasibility using wind-tunnel experiments. Subsequently, we analysed superposition effects of wind speed and concentration fields for different types of EFRTs. The results show that high concentrations of vapor are found near the rim gap of the floating deck and above the floating deck surface. At different ambient wind speeds, interference between tanks is different. When the ambient wind speed is greater than 2 m/s, vapor concentration in leeward area of the rear tank is greater than that between two tanks, which makes it easy to reach explosion limit. It is suggested that more monitoring should be conducted near the bottom area of the rear tank and upper area on the left of the floating deck. Superposition in a downwind direction from the EFRTs becomes more obvious with an increase in the number of EFRTs; vapor superposition occurs behind two leeward tanks after leakage from four large EFRTs. Considering safety, environmental protection, and personnel health, appropriate measures should be taken at these positions for timely monitoring, and control.

Heat Transfer Effects During Cold Dense Gas Dispersion: Wind-Tunnel Simulation of Cold Gas Spills

1986 ◽  
Vol 108 (1) ◽  
pp. 9-15 ◽  
Author(s):  
R. N. Meroney ◽  
D. E. Neff
Keyword(s):  
Heat Transfer ◽  
Wind Speed ◽  
Wind Tunnel ◽  
Transfer Effects ◽  
Concentration Data ◽  
Gas Dispersion ◽  
Humidity Effects ◽  
Low Wind Speed ◽  
Wind Tunnel Simulation ◽  
Heat Transfer Effects

Wind-tunnel concentration data were obtained for continuous area releases of ambient temperature Freon–air mixtures, cold N2, cold CO2, and cold CH4 clouds. Heat transfer and humidity effects on model concentration distributions were significant for methane plumes when surface Richardson numbers Ri* were large (i.e., low wind speed and high boiloff rate conditions). At field scales heat transfer and humidity will still play a role in the dispersion of methane spill cases, but plume dilution and liftoff are not expected to be as exaggerated as for the model cases.

Experimental Simulation on Aerodynamic Character of D-Shaped Iced Conductor

2012 ◽  
Vol 614-615 ◽  
pp. 1405-1409
Author(s):  
Xin Min Li ◽  
Kuan Jun Zhu ◽  
Bin Liu
Keyword(s):  
Numerical Simulation ◽  
Wind Speed ◽  
Wind Tunnel ◽  
Transmission Line ◽  
Driving Force ◽  
Experimental Simulation ◽  
Key Factor ◽  
Simulation And Experiment ◽  
And Control

The dynamics force of iced-conductor is the driving force of galloping; its variation is depended on the aerodynamic character of iced conductor. The aerodynamic character of iced conductor is the key factor of galloping of iced-conductor, but the result of theoretically analysis and numerical simulation isn’t suited for the requirement of transmission line project. In the paper, basing on the theoretically analysis and numerical simulation, the simulation tests in wind tunnel of D-shaped iced conductor is stetted up and put into practice under different wind speed and iced thickness, and then the systemic study is carried into execution. The result of research is indicated that there is a better coherence between the numerical simulation and experiment test, and the variation rules of parameters is obvious with the different iced thickness, the result of numerical simulation is the beneficial supplement to the experiment test. The result can not only provide the original date for the galloping analysis, but also validate the affectivity of numerical simulation, support the research of mechanism and control of galloping.

Wind tunnel simulation experiment of mountain dunes

1999 ◽  
Vol 42 (1) ◽  
pp. 49-59 ◽  
Author(s):  
Liu Xianwan ◽  
Li Sen ◽  
Shen Jianyou
Keyword(s):  
Wind Tunnel ◽  
Simulation Experiment ◽  
Wind Tunnel Simulation

Spray Drift from Dicamba and Glyphosate Applications in a Wind Tunnel

2017 ◽  
Vol 31 (3) ◽  
pp. 387-395 ◽  
Author(s):  
Guilherme Sousa Alves ◽  
Greg R. Kruger ◽  
João Paulo A. R. da Cunha ◽  
Bruno C. Vieira ◽  
Ryan S. Henry ◽  
...  
Keyword(s):  
Wind Speed ◽  
Wind Tunnel ◽  
Laser Diffraction ◽  
Spray Drift ◽  
Downwind Distance ◽  
Fluorescent Tracer ◽  
Drift Potential ◽  
Herbicide Treatments ◽  
Low Speed Wind Tunnel ◽  
Nozzle Type

With the recent introductions of glyphosate- and dicamba-tolerant crops, such as soybean and cotton, there will be an increase in POST-applied tank-mixtures of these two herbicides. However, few studies have been conducted to evaluate drift from dicamba applications. This study aimed to evaluate the effects of dicamba with and without glyphosate sprayed through standard and air induction flat-fan nozzles on droplet spectrum and drift potential in a low-speed wind tunnel. Two standard (XR and TT) and two air induction (AIXR and TTI) 110015 nozzles were used. The applications were made at 276 kPa pressure in a 2.2 ms−1 wind speed. Herbicide treatments evaluated included dicamba alone at 560 gaeha−1 and dicamba+glyphosate at 560+1,260 gaeha−1. The droplet spectrum was measured using a laser diffraction system. Artificial targets were used as drift collectors, positioned in a wind tunnel from 2 to 12 m downwind from the nozzle. Drift potential was determined using a fluorescent tracer added to solutions, quantified by fluorimetry. Dicamba droplet spectrum and drift depended on the association between herbicide solution and nozzle type. Dicamba alone produced coarser droplets than dicamba+glyphosate when sprayed through air induction nozzles. Drift decreased exponentially as downwind distance increased and it was reduced using air induction nozzles for both herbicide solutions.

scholarly journals Drift Evaluation of a Quadrotor Unmanned Aerial Vehicle (UAV) Sprayer: Effect of Liquid Pressure and Wind Speed on Drift Potential Based on Wind Tunnel Test

2021 ◽  
Vol 11 (16) ◽  
pp. 7258
Author(s):  
Qi Liu ◽  
Shengde Chen ◽  
Guobin Wang ◽  
Yubin Lan
Keyword(s):  
Wind Speed ◽  
Wind Tunnel ◽  
High Efficiency ◽  
Plant Protection ◽  
Spray Drift ◽  
Liquid Pressure ◽  
Agricultural Plant ◽  
Wind Speeds ◽  
Drift Potential ◽  
Test Platform

Background: Unmanned Aerial Vehicles (UAVs) applied to agricultural plant protection is widely used, and the field of operation is expanding due to their high efficiency and pesticide application reduction. However, the work on pesticide drift lags behind the development of the UAV spraying device. Methods: We compared the spray drift potential at four liquid pressures of 2, 3, 4, and 5 bar ejected from the hydraulic nozzles mounted on a UAV test platform exposed to different wind speeds of 2, 4, and 6 m/s produced by a wind tunnel. The combination of the wind tunnel and the UAV test platform was used to obtain strict test conditions. The droplet size distribution under spray drift pressures was measured by a laser diffraction instrument. Results: Increasing the pressure leads to smaller droplet volume diameters and produced fine droplets of less than 100 µm. The deposition in the drift area was elevated at most of the sampling locations by setting higher pressure and faster wind speed. The deposition ratios were all higher than the flow ratios under three wind speeds after the adjustment of pressures. For most samples within a short drift distance (2–8 m), the drift with the rotor motor off was more than an order of magnitude higher than that with the rotor motor on at a pressure of 3 bar. Conclusions: In this study, the wind speed and liquid pressure all had a significant effect on the UAV spray drift, and the rotor wind significantly inhibited a large number of droplets from drifting further.

scholarly journals A Design and Construction of a Wind Tunnel for Engineering Laboratories

2018 ◽  
Vol 192 ◽  
pp. 02069
Author(s):  
Chalida U-tapao ◽  
Seksun Moryadee
Keyword(s):  
Wind Speed ◽  
Wind Tunnel ◽  
Test Area ◽  
Maximum Pressure ◽  
Maximum Height ◽  
Wind Speeds ◽  
Air Blower ◽  
And Control ◽  
The Relationship ◽  
Design And Construction

The propose of this research is to demonstrate a design and construction of a wind tunnel for engineering laboratories in order to study the principles and control wind speeds in the wind tunnel. In an experiment in aerodynamics and engineering, we found that diffuser must have a length equal to or more than twice the length of the test in order to prevent the turbulent flow in the test area. The wind speed control system uses Inverter to control a 3-phase frequency of electricity supplied to air blower. In the experiment, the frequency was adjusted in the range from 20.00 to 50.00 Hz. Experiment results show that wind speeds during the test area are in the range of 14.50 to 38.50 meters per second, and the relationship between frequency (Y) and wind speed (X) during the test is linear as follows: Y = (0.7945 × (X-20)) + 14.629. The maximum pressure is 90.31 kilograms per square meter. This wind tunnel can be used to design buildings with a maximum height of 20 meters according to the Bangkok Metropolis Building Control (2001).

scholarly journals BLOWN SAND ON BEACHES

1982 ◽  
Vol 1 (18) ◽  
pp. 73
Author(s):  
Susumu Kubota ◽  
Kiyoshi Horikawa ◽  
Shintaro Hotta
Keyword(s):  
Wind Speed ◽  
Wind Tunnel ◽  
Vertical Distribution ◽  
Shear Velocity ◽  
Wind Tunnel Experiment ◽  
Transport Rate ◽  
Sand Transport ◽  
Sand Transport Rate ◽  
Empirical Coefficients ◽  
The Vertical Distribution

The blown sand transport rate and the vertical and shore-normal distributions of the wind speed were measured simultaneously on a windy beach. The sand transport rate was measured with conventional total quantity-type traps and with a large trap in the form of a trench. The vertical distribution of the wind speed was measured using an ultrasonic anemometer array consisting of six meters. The distribution of wind speed at a height of 1 m in a section normal to the shoreline was measured with five ultrasonic anemometers. A logarithmic law for the vertical distribution of the wind speed was satisfied, and the wind speed in the section normal to the shoreline was almost constant. The Kawamura and Bagnold formulae were found to predict well the sand transport rate. The trench trap and conventional traps gave empirical coefficients of 1.5 and 1.0, respectively, for the sand transport rate averaged over a section normal to the shoreline. The lower value determined with the conventional traps (1.0) is attributed to their inefficiency compared with the trench trap. In order to obtain data at high shear velocities, a wind tunnel experiment was carried out. This experiment showed that both the Kawamura and Bagnold formulae were valid in the range between 60 to 300 cm/s in the wind shear velocity. The empirical coefficient in the laboratory experiments was 1.0: the difference between the field result with the trench trap and the wind tunnel experiment is attributed to the fluctuations in natural wind.

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