Calibration constant current anemometer probes for aircraft based atmospheric turbulence measurements

1995 ◽  
Author(s):  
C Wisniewski ◽  
B Scruggs ◽  
B Masson ◽  
D Kyrazis ◽  
C Truman
Keyword(s):  
Atmospheric Turbulence ◽  
Constant Current ◽  
Calibration Constant ◽  
Turbulence Measurements

scholarly journals Fabrication of freestanding Pt nanowires for use as thermal anemometry probes in turbulence measurements

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Hai Le-The ◽  
Christian Küchler ◽  
Albert van den Berg ◽  
Eberhard Bodenschatz ◽  
Detlef Lohse ◽  
...  
Keyword(s):  
Room Temperature ◽  
Fluid Velocity ◽  
Current Mode ◽  
Constant Current ◽  
Small Scale ◽  
Turbulence Measurements ◽  
High Dynamic ◽  
Scale Turbulence ◽  
Constant Current Mode ◽  
Pt Nanowires

AbstractWe report a robust fabrication method for patterning freestanding Pt nanowires for use as thermal anemometry probes for small-scale turbulence measurements. Using e-beam lithography, high aspect ratio Pt nanowires (~300 nm width, ~70 µm length, ~100 nm thickness) were patterned on the surface of oxidized silicon (Si) wafers. Combining wet etching processes with dry etching processes, these Pt nanowires were successfully released, rendering them freestanding between two silicon dioxide (SiO2) beams supported on Si cantilevers. Moreover, the unique design of the bridge holding the device allowed gentle release of the device without damaging the Pt nanowires. The total fabrication time was minimized by restricting the use of e-beam lithography to the patterning of the Pt nanowires, while standard photolithography was employed for other parts of the devices. We demonstrate that the fabricated sensors are suitable for turbulence measurements when operated in constant-current mode. A robust calibration between the output voltage and the fluid velocity was established over the velocity range from 0.5 to 5 m s−1 in a SF6 atmosphere at a pressure of 2 bar and a temperature of 21 °C. The sensing signal from the nanowires showed negligible drift over a period of several hours. Moreover, we confirmed that the nanowires can withstand high dynamic pressures by testing them in air at room temperature for velocities up to 55 m s−1.

222Rn as indicator of atmospheric turbulence: measurements at Lake Maggiore and on the pre-Alps

2006 ◽  
Vol 86 (2) ◽  
pp. 271-288 ◽  
Author(s):  
Lucia Sesana ◽  
Barbara Ottobrini ◽  
Giancarla Polla ◽  
Ugo Facchini
Keyword(s):  
Atmospheric Turbulence ◽  
Turbulence Measurements ◽  
Lake Maggiore

scholarly journals Evaluation of wake influence on high-resolution balloon-sonde measurements

2019 ◽  
Vol 12 (8) ◽  
pp. 4191-4210 ◽  
Author(s):  
Jens Söder ◽  
Michael Gerding ◽  
Andreas Schneider ◽  
Andreas Dörnbrack ◽  
Henrike Wilms ◽  
...  
Keyword(s):  
High Resolution ◽  
Uncertainty Analysis ◽  
Atmospheric Turbulence ◽  
Evaluation Tool ◽  
Turbulence Measurements ◽  
Wake Effects ◽  
Humidity Measurements ◽  
Average Probability ◽  
Vertical Winds

Abstract. Balloons are used for various in situ measurements in the atmosphere. On turbulence measurements from rising balloons there is a potential for misinterpreting wake-created fluctuations in the trail of the balloon for atmospheric turbulence. These wake effects have an influence on temperature and humidity measurements from radiosondes as well. The primary aim of this study is to assess the likelihood for wake encounter on the payload below a rising balloon. Therefore, we present a tool for calculating this probability based on radiosonde wind data. This includes a retrieval of vertical winds from the radiosonde and an uncertainty analysis of the wake assessment. Our wake evaluation tool may be used for any balloon–gondola distance and provides a significant refinement compared to existing assessments. We have analysed wake effects for various balloon–gondola distances applying atmospheric background conditions from a set of 30 radiosondes. For a standard radiosonde we find an average probability for wake encounter of 28 %, pointing out the importance of estimating wake effects on sounding balloons. Furthermore, we find that even millimetre-sized objects in the payload can have significant effects on high-resolution turbulence measurements, if they are located upstream of the turbulence sensor.

Atmospheric turbulence measurements at Ali Observatory, Tibet

2012 ◽  
Author(s):  
Liyong Liu ◽  
Yongqiang Yao ◽  
Jean Vernin ◽  
Merieme Chadid ◽  
Yiping Wang ◽  
...  
Keyword(s):  
Atmospheric Turbulence ◽  
Turbulence Measurements
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