INFLUENCE OF PLANT RESIDUE ON SAND FLOW IN A WIND TUNNEL

1968 ◽  
Vol 48 (1) ◽  
pp. 49-52 ◽  
Author(s):  
Frederick Bisal
Keyword(s):  
Wind Tunnel ◽  
Wind Velocity ◽  
Initial Phase ◽  
Rapid Decrease ◽  
Plant Residue ◽  
Surface Sand ◽  
Wheat Stubble ◽  
Sand Flow ◽  
The Relationship

A wind tunnel was used to study the effect of various amounts of standing wheat stubble on sand flow. In general, the relationship between sand flow and the amount of wheat stubble tended to be sigmoidal. There was an initial phase when small amounts of stubble had very little effect on sand flow, followed by a very rapid decrease in flow when additional increments of stubble were added to the surface. Sand flow approached zero at stubble rates ranging from 1,200 kg/ha for a wind velocity of 5.36 m/sec to 7,200 kg/ha for a wind velocity of 8.49 m/sec. At a wind velocity of 10.28 m/sec the addition of 1,800 kg/ha of wheat stubble tended to increase sand flow.

EFFECT OF NONERODIBLE AGGREGATES AND WHEAT STUBBLE ON INITIATION OF SOIL DRIFTING

1970 ◽  
Vol 50 (1) ◽  
pp. 31-34 ◽  
Author(s):  
FREDERICK BISAL ◽  
W. S. FERGUSON
Keyword(s):  
Wind Tunnel ◽  
Wind Velocity ◽  
Soil Aggregates ◽  
Soil Surface ◽  
Wheat Stubble ◽  
The Relationship

The wind velocity required to initiate movement of soil with varying amounts of standing wheat stubble and varying proportions of erodible and nonerodible soil aggregates was determined in a wind tunnel. The relationship between these variables was calculated as logeI = 6.0438 + 0.0001774 S + 0.02332 C where I is the initiating velocity in cm/sec as measured at a height of 30.5 cm above the soil surface, S is the amount of standing wheat stubble (approximately 15 cm tall) in kg/ha, and C is the percentage of soil aggregates greater than 1 mm in diameter in a soil sample.The wind velocity required to initiate erosion is proposed as an index of erodibility of farm fields.

A numerical approach for the assessment of crosswind effects on barrier-protected trains running on bridges

2021 ◽  
Author(s):  
Giuseppe Porpiglia ◽  
Paolo Schito ◽  
Tommaso Argentini ◽  
Alberto Zasso
Keyword(s):  
Wind Tunnel ◽  
Velocity Profile ◽  
Wind Velocity ◽  
Aerodynamic Force ◽  
Numerical Approach ◽  
Aerodynamic Performance ◽  
Vehicle Speed ◽  
Initial Condition ◽  
Cfd Analyses ◽  
Moving Train

<p>This paper introduces a new methodology to assess the influence of a windscreen on the crosswind performance of trains running on a bridge. Considering the difficulties encountered in both carrying out wind tunnel tests that consider the vehicle speed or complete CFD analyses, a simplified CFD approach is here discussed. Instead of simulating simultaneously the windscreen plus the moving train, the numerical problem is split into two parts: firstly, a simulation of the windshield alone is used to extract the perturbed velocity profile at the railway location; secondly, this profile used as an inlet condition for the wind velocity acting on an isolated train. The method is validated against a complete train plus windshield simulation in terms of pressure distribution and aerodynamic force coefficients on the train, and flow streamlines. This approach opens to the possibility of evaluating the aerodynamic performance of a vehicle on bridges considering bridge and vehicle as separated. Wind velocity profiles measured on the bridge during a wind tunnel campaign could be used as the initial condition for numerical simulations on vehicles.</p>

scholarly journals Analysis of Stress and Strain to Determine the Pressure Changes in Tight-Fitting Garment

2020 ◽  
Vol 20 (1) ◽  
pp. 49-55
Author(s):  
Nareerut Jariyapunya ◽  
Blažena Musilová
Keyword(s):  
Mechanical Properties ◽  
Mathematical Models ◽  
Initial Phase ◽  
Circumferential Stress ◽  
The Body ◽  
Stress And Strain ◽  
Laplace’S Law ◽  
Pressure Changes ◽  
The Relationship ◽  
Laplace's Law

AbstractBased on the mechanical properties of stretch fabrics and Laplace’s law, the mathematical models have been developed enabling one to determine the values of the relationship between the fabric strain and the circumferential stress depending on pressure and diameter of the body. The results obtained refer to the values of the parameters assessed for the initial phase of their exploitation, which allow us to preliminarily predict the values of these parameters.

scholarly journals The effect of wind direction on drift control by snow fences

2001 ◽  
Vol 32 ◽  
pp. 159-162 ◽  
Author(s):  
Yukari Takeuchi ◽  
Shun’ichi Kobayashi ◽  
Takeshi Sato ◽  
Kaoru Izumi ◽  
Kenji Kosugi ◽  
...  
Keyword(s):  
Wind Tunnel ◽  
Wind Velocity ◽  
Wind Direction ◽  
The Other ◽  
First Case ◽  
Snow Fence ◽  
Snow Fences ◽  
Set Up ◽  
Cold Wind ◽  
Drift Control

AbstractSnowdrifting processes and the wind-velocity profiles around a collector and a blower snow fence were investigated in a cold wind tunnel. The purpose was to ascertain the effect of wind direction on drift control by snow fences. Three different cases were studied for both types of snow fence, and the resultant snowdrifts were compared. In the first case, the snow fence was perpendicular to the wind direction. In the second and third cases, it was tilted by 30° and 45°. When the collector snow fence was tilted, the amounts of snowdrift were much less than when the fence was perpendicular to the wind direction, because the area with low wind velocity was reduced to half behind the tilted fence. On the other hand, the blowing effect of the blower snow fence increased when it was set up at an angle to the wind direction. It is necessary to investigate the position where the blown snow is deposited by the tilted blower snow fence.

Photogrammetric Investigation of the Flying Shape of Spinnakers in a Twisted Flow Wind Tunnel

2009 ◽  
Author(s):  
Kai Graf ◽  
Olaf Müller
Keyword(s):  
Image Processing ◽  
Pattern Recognition ◽  
High Resolution ◽  
Wind Tunnel ◽  
Wind Velocity ◽  
Digital Cameras ◽  
Pattern Recognition Methods ◽  
Twisted Flow ◽  
High Resolution Images ◽  
The Impact

This paper describes a method for the acquisition of the flying shape of spinnakers in a twisted flow wind tunnel. The method is based on photogrammetry. A set of digital cameras is used to obtain high resolution images of the spinnaker from different viewing angles. The images are post-processed using image-processing tools, pattern recognition methods and finally the photogrammetry algorithm. Results are shown comparing design versus flying shape of the spinnaker and the impact of wind velocity and wind twist on the flying shape. Finally some common rules for optimum spinnaker trimming are investigated and examined.

scholarly journals A Wind Tunnel Study on the Correlation between Urban Space Quantification and Pedestrian–Level Ventilation

Atmosphere ◽  
2019 ◽  
Vol 10 (10) ◽  
pp. 564 ◽  
Author(s):  
Li ◽  
Peng ◽  
Ji ◽  
Hu ◽  
Ding
Keyword(s):  
Wind Speed ◽  
Wind Tunnel ◽  
Wind Velocity ◽  
Urban Space ◽  
Speed Ratio ◽  
Spatial Indices ◽  
Spatial Characteristics ◽  
Spatial Partition ◽  
Mean Wind Speed ◽  
Partition Method

Correlation research on urban space and pedestrian–level wind (PLW) environments is helpful for improving the wind comfort in complex urban space. It could also be significant for building and urban design. Correlation research is usually carried out in a space with clear urban spatial characteristics, so it is necessary to define the space first. In this paper, a typical urban area in Nanjing, China, is selected as the research object, and a spatial partition method is used to divide the real complex urban space into subspaces. The urban spatial characteristics of such subspaces are quantified using three urban spatial indices: openness (O), area (A), and shape (S). By comparing the quantitative results, 24 (12 pairs) subspaces with prominent urban spatial indices are selected as the correlation research cases. The 24 subspaces also provide a reference for the layout of the measurement points in a wind tunnel experiment. This is a new arrangement for locating the measurement points of a wind tunnel for correlation research. In the experiment, 45 measurement points are located, and the mean wind velocity of four different wind directions at 45 measurement points is experimented. The results clearly show that, when the experimental conditions are the same, the changes of mean wind velocity ratio (UR) of 24 (12pairs) subspaces under the four experimental wind directions are close. The URs of the subspaces are not significantly affected by the wind direction, which is affected more by the subspaces’ spatial characteristics. When making the correlation analysis between mean wind speed ratio and spatial characteristics’ indices, a direct numerical comparison was not able to find a correlation. By comparing the difference values of mean wind speed (△UR) and indices between each pair of subspaces, the correlation between UR and openness of subspaces were found. Limited by spatial partition method, the correlation between UR and the other indices was not obvious.

scholarly journals Intercomparison of Unmanned Aircraftborne and Mobile Mesonet Atmospheric Sensors

2016 ◽  
Vol 33 (8) ◽  
pp. 1569-1582 ◽  
Author(s):  
Adam L. Houston ◽  
Roger J. Laurence ◽  
Tevis W. Nichols ◽  
Sean Waugh ◽  
Brian Argrow ◽  
...  
Keyword(s):  
Wind Tunnel ◽  
Wind Velocity ◽  
Vertical Velocity ◽  
Humidity Sensor ◽  
Heavy Precipitation ◽  
Unmanned Aircraft ◽  
Sensor Performance ◽  
The Tempest ◽  
Aircraft System ◽  
The Impact

AbstractResults are presented from an intercomparison of temperature, humidity, and wind velocity sensors of the Tempest unmanned aircraft system (UAS) and the National Severe Storms Laboratory (NSSL) mobile mesonet (NSSL-MM). Contemporaneous evaluation of sensor performance was facilitated by mounting the Tempest wing with attached sensors to the NSSL-MM instrument rack such that the Tempest and NSSL-MM sensors could collect observations within a nearly identical airstream. This intercomparison was complemented by wind tunnel simulations designed to evaluate the impact of the mobile mesonet vehicle on the observed wind velocity.The intercomparison revealed strong correspondence between the temperature and relative humidity (RH) data collected by the Tempest and the NSSL-MM with differences generally within sensor accuracies. Larger RH differences were noted in the presence of heavy precipitation; however, despite the exposure of the Tempest temperature and humidity sensor to the airstream, there was no evidence of wet bulbing within precipitation. Wind tunnel simulations revealed that the simulated winds at the location of the NSSL-MM wind monitor were ~4% larger than the expected winds due to the acceleration of the flow over the vehicle. Simulated vertical velocity exceeded 1 m s−1 for tunnel inlet speeds typical of a vehicle moving at highway speeds. However, the theoretical noncosine reduction in winds that should result from the impact of vertical velocity on the laterally mounted wind monitor was found to be negligible across the simulations. Comparison of the simulated and observed results indicates a close correspondence, provided the crosswind component of the flow is small.

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