A Low Velocity Wind Tunnel to Evaluate Inhalability and Sampler Performance for Large Dust Particles

1995 ◽  
Vol 10 (6) ◽  
pp. 549-556 ◽  
Author(s):  
William C. Hinds ◽  
Ti-Lin Kuo
Keyword(s):  
Wind Tunnel ◽  
Dust Particles ◽  
Low Velocity

Turbulent plumes of heat, moist heat, and carbon dioxide elicit upwind anemotaxis in tsetse flies Glossina morsitans morsitans Westwood (Diptera: Glossinidae)

2002 ◽  
Vol 80 (7) ◽  
pp. 1149-1155 ◽  
Author(s):  
W G Evans ◽  
R H Gooding
Keyword(s):  
Carbon Dioxide ◽  
Wind Tunnel ◽  
Relative Humidity ◽  
Glossina Morsitans Morsitans ◽  
Tsetse Flies ◽  
Glossina Morsitans ◽  
Low Velocity ◽  
Upwind Flight ◽  
Moist Heat ◽  
Heated Air

The roles and interactions of turbulent plumes of heat, moist heat, and carbon dioxide in mediating upwind flight of adult tsetse flies (Glossina morsitans morsitans Westwood) were investigated using a wind tunnel in a constant-environment chamber. Heat fluctuations in the plume that were detected by a thermocouple and displayed as oscilloscope traces allowed direct visualization of the structures of the plumes. Significantly more flies flew upwind when exposed to plumes of (i) carbon dioxide (0.0051% above background) and air (58% relative humidity) compared with air alone; (ii) carbon dioxide and heated air (35% relative humidity and temperature fluctuating up to 0.09°C above background) compared with carbon dioxide and air; and (iii) carbon dioxide and moist (82% relative humidity) heated air (temperature fluctuating up to 0.05°C above background) compared with carbon dioxide and heated air. However, there were no significant differences in upwind flight of flies exposed to plumes of (i) air compared with humidified air (65% relative humidity); (ii) carbon dioxide and heated air compared with heated air alone; and (iii) carbon dioxide and moist heated air compared with moist heated air alone. Recorded temperature fluctuations in heat plumes transported downwind from a tethered steer in a pasture showed patterns similar to those produced in the wind-tunnel plumes. These results suggest that host emissions of carbon dioxide alone and combined heat and moisture carried downwind by low-velocity winds elicit upwind anemotaxis in tsetse flies, which distinguish these emissions from a background of lower atmospheric levels.

Effect on Water Leak of Tiled Roofs by Wind Flow Over Japanese Residence

2010 ◽  
Author(s):  
Satoru Okamoto
Keyword(s):  
Wind Tunnel ◽  
Low Frequency ◽  
Video Camera ◽  
Wind Flow ◽  
Leak Test ◽  
Low Velocity ◽  
Artificial Rainfall ◽  
Water Leak ◽  
Series Of Experiments ◽  
Set Up

This paper describes a water leak test of roof tiles. The 100 roof tiles were set up on 10 lines and 10 rows on the pitched roof in the downstream of the flow from the wind tunnel. The flow velocity was increased gradually from the low velocity to the high velocity, and the effects of the wind on the roof tiles were investigated by the water leak test. The situation of the water leak test was filmed by video camera. Two accelerometers were simultaneously used. The roof tiles which showed significant vibration at any velocity were found in a series of experiments and the accelerometers were attached to the two neighboring roof tiles on the model roof. The water leak phenomena in the experiment by using the artificial rainfall apparatus are discussed in this paper. Some mechanisms with relatively large amplitudes at low-frequency vibrations, which caused water leak phenomena were made clear.

The SANDEE campaign: Electrical effects during sand transport by aeolian processes in the Negev desert and implications for Mars

2020 ◽  
Author(s):  
Itzhak Katra ◽  
Yoav Yair
Keyword(s):  
Wind Tunnel ◽  
Electric Field ◽  
Field Experiments ◽  
Negev Desert ◽  
Energy Output ◽  
Dust Particles ◽  
Sand Transport ◽  
Solar Panels ◽  
Aeolian Processes ◽  
Airborne Dust

<p>The electrification of mineral sand/dust particles during aeolian processes is a well-documented phenomenon both in natural settings and in laboratory experiments. When in motion, small airborne dust particles collide with other suspended particles or impact the surface through the kinetic energy they acquire from the ambient wind. Field experiments will be conducted in conjunction with the AMEDEE-2020 Analog Mars Mission, planned for November 2020 in the Ramon Crater in southern Israel and led by the Austrian Space Forum. During SANDEE, we will deploy a portable wind-tunnel (Katra et al., 2016) at the site, and record particle movements in conditions that simulate sand storms of varying speeds. We will use local Negev desert, as well as Mars-simulant, soil samples that will be placed inside the wind-tunnel. We will measure particles' dynamic, mineralogical and electrical characteristics as they are blown by wind inside the tunnel.  A JCI 114 portable electric field detector will be used to to measure the amplification of the ambient electric field during sand movement. A vertical array of traps oriented along the wind direction will be used for sampling particles, in order to calculate the related sand fluxes and to analyze particle characteristics. The experiment will be repeated at night under dark conditions, in order to observe if light is emitted from electrified dust, due to corona discharges.</p><p>We expect that SANDEE will help decipher wind-speed/aerosol/electrical charge relationships. These have practical implications for future Mars landers, because airborne sand particles are likely to interfere with communications and also to impede the energy output of solar panels due to the electrical adhesion of charged aerosol.</p>

Measurement of the uniformity of particle deposition of filter cassette sampling in a low velocity wind tunnel

1990 ◽  
Vol 21 ◽  
pp. S621-S624 ◽  
Author(s):  
C.C. Wang ◽  
R.A. Fletcher ◽  
E.B. Steel ◽  
J.W. Gentry
Keyword(s):  
Wind Tunnel ◽  
Particle Deposition ◽  
Low Velocity

scholarly journals A Comparison of Contact Charging and Impact Ionization in Low Velocity Impacts: Implications for Dust Detection in Space

2020 ◽  
Author(s):  
Tarjei Antonsen ◽  
Ingrid Mann ◽  
Jakub Vaverka ◽  
Libor Nouzak ◽  
Åshild Fredriksen
Keyword(s):  
Impact Ionization ◽  
Interplanetary Space ◽  
Dust Particles ◽  
Low Velocity ◽  
Charge Generation ◽  
Earth’S Atmosphere ◽  
Contact Charging ◽  
Metal Metal ◽  
Dust Detection ◽  
Earth's Atmosphere

Abstract. We investigate the generation of charge during collision of projectiles with sizes below ~ 1 μm and metal surfaces at speeds ~ 0.1 km/s. This corresponds to speeds above the elastic limit and well below speeds where volume ionization can occur. The conditions that we consider apply to dust particles naturally occurring in space and in Earth's upper atmosphere and their direct impacts on rockets, spacecraft, and impacts of secondary ejecta. We introduce a model of capacitive contact charging in which we allow for projectile fragmentation upon impact, and show that this model describes measurements of metal-metal impacts in the laboratory and in-situ measurements of dust in the Earth's atmosphere well. We have considered the utilization of our model for different scenarios in interplanetary space and in Earth's atmosphere. From this discussion we find it likely that our work can be employed in a number of situations where impact velocities are relatively small. Furthermore, we have discussed the thermodynamics of the low velocity solution of shock wave ionization, and conclude that the impurity charging effect utilized in the much used model of Drapatz and Michel (1974) does not sufficiently describe charge generation at impact speeds below a few kilometers per second. Consequently, impact charging at low speeds cannot be described with a Saha-solution.

scholarly journals A comparison of contact charging and impact ionization in low-velocity impacts: implications for dust detection in space

2021 ◽  
Vol 39 (3) ◽  
pp. 533-548
Author(s):  
Tarjei Antonsen ◽  
Ingrid Mann ◽  
Jakub Vaverka ◽  
Libor Nouzak ◽  
Åshild Fredriksen
Keyword(s):  
Shock Wave ◽  
Impact Ionization ◽  
Dust Particles ◽  
Low Velocity ◽  
Direct Ionization ◽  
Contact Charging ◽  
Naturally Occurring ◽  
Metal Metal ◽  
Dust Detection ◽  
Volume Ionization

Abstract. We investigate the generation of charge due to collision between projectiles with sizes below ∼1 µm and metal surfaces at speeds ∼0.1 to 10 km s−1. This corresponds to speeds above the elastic limit and well below speeds where volume ionization can occur. Impact charge production at these low to intermediate speeds has traditionally been described by invoking the theory of shock wave ionization. By looking at the thermodynamics of the low-velocity solution of shock wave ionization, we find that such a mechanism alone is not sufficient to account for the recorded charge production in a number of scenarios in the laboratory and in space. We propose a model of capacitive contact charging that involves no direct ionization, in which we allow for projectile fragmentation upon impact. Furthermore, we show that this model describes measurements of metal–metal impacts in the laboratory well. We also address contact charging in the context of ice-on-metal collisions and apply our results to rocket observations of mesospheric dust. In general, we find that contact charging dominates at speeds of up to a few kilometres per second and complements shock wave ionization up to speeds where direct ionization can take place. The conditions that we consider can be applied to dust particles naturally occurring in space and in Earth's upper atmosphere and their direct impacts on rockets, spacecraft, and impacts of secondary ejecta.

scholarly journals Measurements of dust deposition velocity in a wind-tunnel experiment

2014 ◽  
Vol 14 (7) ◽  
pp. 9439-9474 ◽  
Author(s):  
J. Zhang ◽  
Y. Shao ◽  
N. Huang
Keyword(s):  
Wind Tunnel ◽  
Deposition Velocity ◽  
Wind Tunnel Experiment ◽  
Dust Particles ◽  
Dust Deposition ◽  
Wind Speeds ◽  
Deposition Velocities ◽  
Development And Validation ◽  
Single Instrument ◽  
Entire Dataset

Abstract. In this study, we present the results of a wind-tunnel experiment on dust deposition. A new method is proposed to derive dust deposition velocity from the PDA (Particle Dynamics Analysis) particle-velocity and particle-size measurements. This method has the advantage that the motions of individual dust particles are directly observed and all relevant data for computing dust deposition velocity is collected using a single instrument, and therefore the measurement uncertainties are reduced. The method is used in the wind-tunnel experiment to measure the dust deposition velocities for different particle sizes, wind speeds and surface conditions. For a sticky-smooth wood surface and a water surface, the observed dust deposition velocities are compared with the predictions using a dust deposition scheme, and the entire dataset is compared with the data found in the literature. From the wind-tunnel experiments, a relatively reliable dataset of dust deposition velocity is obtained, which is of considerable value for the development and validation of dust deposition schemes.

Design and construction of a didactic low-velocity wind tunnel

2021 ◽  
Author(s):  
Arthur Queiroga ◽  
Olexiy Shynkarenko ◽  
Rhander Viana
Keyword(s):  
Wind Tunnel ◽  
Low Velocity ◽  
Design And Construction
Sign in / Sign up

Export Citation Format

Share Document