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Journal articles on the topic 'Hot wire anemometers'

Author: Grafiati

Published: 4 June 2021

Last updated: 14 February 2022

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1

Pupyshev, I. D., A. A. Chepushtanov, and Yu V. Beketov. "Calibration Unit for Hot-Wire Anemometers." Measurement Techniques 47, no. 2 (February 2004): 168–71. http://dx.doi.org/10.1023/b:mete.0000026216.28905.d4.

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2

Al-Garni, Abdullah M. "Low speed calibration of hot-wire anemometers." Flow Measurement and Instrumentation 18, no. 2 (April 2007): 95–98. http://dx.doi.org/10.1016/j.flowmeasinst.2007.01.003.

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3

Ligęza, Paweł. "Modification of Hot-Wire Anemometers Frequency Bandwidth Measurement Method." Sensors 20, no. 6 (March 13, 2020): 1595. http://dx.doi.org/10.3390/s20061595.

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In measurements of fast-changing flows, one of the key issues is knowledge of the anemometer frequency bandwidth. In such measurements, the measurement technique often used is hot-wire anemometry. The determination and optimization of the measurement bandwidth of the hot-wire system is very important for the quality of the measurements carried out. One of the methods used is square-wave or sine-wave electrical testing. The article proposes modification of this method, which involves applying an electrical test signal wirelessly directly to the sensor, using transformer inductive coupling. This modification may in some cases be beneficial and find application in selected metrological problems. The article describes the modified method and its example application.

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4

Manshadi, Mojtaba Dehghan, and Mohamad Kazemi Esfeh. "A New Approach about Heat Transfer of Hot-Wire Anemometer." Applied Mechanics and Materials 232 (November 2012): 747–51. http://dx.doi.org/10.4028/www.scientific.net/amm.232.747.

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The hot-wire anemometer is a famous thermal transducer for turbulence measurements. The fundamental principle of hot-wire anemometer is based on the convective heat transfer, since the heat transfer is directly proportional to the temperature difference between the sensor and the fluid, hence ambient temperature variations are one of the most important error sources in the measurements with the hot-wire anemometers. Many methods have been proposed to compensate for the ambient temperature variations. In such methods the effect of temperature drift is only considered and the effect of Nusselt number is ignored. In the present research the effect of air flow temperature variations on the response of constant temperature anemometer has been studied experimentally. Furthermore, with the basis of air flow velocity and ambient temperature variations, the percentage errors in velocity measurements have been estimated. Finally, based on achieved results, an accurate method has been proposed to compensate the air flow temperature variations.

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5

Здоренко, В. Г., and К. В. Себко. "ДОСЛІДЖЕННЯ МЕТРОЛОГІЧНИХ ХАРАКТЕРИСТИК ТЕРМОАНЕМОМЕТРА НА ОСНОВІ ВИМІРЮВАЛЬНОГО КОНТРОЛЮ ПАРАМЕТРІВ ТЕПЛОВОГО ПОТОКУ МИКРОХВИЛЬОВОЇ КАМЕРИ." Bulletin of the Kyiv National University of Technologies and Design. Technical Science Series 146, no. 3 (January 11, 2021): 37–47. http://dx.doi.org/10.30857/1813-6796.2020.3.3.

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The purpose of the article is to study the rational operation of the hot-wire anemometer in accordance with the dynamic characteristics and measurement errors, when implementing the process of drying raw nuts in an industrial microwave chamber. The technique of studying the informative parameters of the heat flow was used to determine the rational mode of operation of the hot-wire anemometer and to reduce the time of heat treatment of nut raw materials. The characteristics of the thermal transient process of drying raw nut materials in a microwave chamber are investigated. Theoretical substantiation and an algorithm for determining the dynamic characteristics of the hot-wire anemometer under the external sinusoidal effect of the heat flow temperature are given, algorithms for determining the instantaneous values of the temperature increments of the hot-wire anemometer sensitive element in the process of drying nut raw materials are given. On the basis of the general theory of errors of indirect measurements in the investigated range of variation of the rate V of the heat flow, the values of the relative systematic errors of indirect measurements of the rate of heat flow in the range from 10 to 40 m / s were determined. It was found that in accordance with the dynamic characteristics and measurement errors when blowing a moving heat flow of nut raw materials, the most rational is the mode of constant resistance of the hot-wire anemometer. Solutions of the differential equation describing the dynamic heat process when the temperature of the moving heat flow changes according to the periodic law, i.e. stationary, non-stationary and complete. The results of calculating the constant times of the hot-wire anemometer thread τп and τтп of the moving heat flow, respectively, were τп = 0.59 s and τтп = 0.6 s, the time constant of the hot-wire anemometer is practically commensurate with the thermal time constant of the moving stream blowing over the nut raw material. It consists in the fact that the theoretical position of the hot-wire anemometer has been further developed in the direction of researching the characteristics of the thermal transient process of processing nut raw materials, all this makes it possible to determine the ranges of changes in the signals of the thermal device, which correspond to the ranges of change in the informative characteristics of the moving heat flow, and also allows the selection measuring equipment, establish rational operating modes of hot-wire anemometers and automated devices that use them in accordance with errors and sensitivities. The proposed algorithms for determining the informative parameters of the heat flow in the study of the transient process of heat transfer from the moving air flow to the sensitive element of the transducer, the results of the errors in measuring the velocity V of the moving heat flow, make it possible to calculate, design and create measuring automated devices that use hot-wire anemometers in food and processing industry, instrument making and chemical engineering.

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6

Здоренко, В. Г., and К. В. Себко. "ДОСЛІДЖЕННЯ МЕТРОЛОГІЧНИХ ХАРАКТЕРИСТИК ТЕРМОАНЕМОМЕТРА НА ОСНОВІ ВИМІРЮВАЛЬНОГО КОНТРОЛЮ ПАРАМЕТРІВ ТЕПЛОВОГО ПОТОКУ МИКРОХВИЛЬОВОЇ КАМЕРИ." Bulletin of the Kyiv National University of Technologies and Design. Technical Science Series 146, no. 3 (January 11, 2021): 37–47. http://dx.doi.org/10.30857/1813-6796.2020.3.3.

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The purpose of the article is to study the rational operation of the hot-wire anemometer in accordance with the dynamic characteristics and measurement errors, when implementing the process of drying raw nuts in an industrial microwave chamber. The technique of studying the informative parameters of the heat flow was used to determine the rational mode of operation of the hot-wire anemometer and to reduce the time of heat treatment of nut raw materials. The characteristics of the thermal transient process of drying raw nut materials in a microwave chamber are investigated. Theoretical substantiation and an algorithm for determining the dynamic characteristics of the hot-wire anemometer under the external sinusoidal effect of the heat flow temperature are given, algorithms for determining the instantaneous values of the temperature increments of the hot-wire anemometer sensitive element in the process of drying nut raw materials are given. On the basis of the general theory of errors of indirect measurements in the investigated range of variation of the rate V of the heat flow, the values of the relative systematic errors of indirect measurements of the rate of heat flow in the range from 10 to 40 m / s were determined. It was found that in accordance with the dynamic characteristics and measurement errors when blowing a moving heat flow of nut raw materials, the most rational is the mode of constant resistance of the hot-wire anemometer. Solutions of the differential equation describing the dynamic heat process when the temperature of the moving heat flow changes according to the periodic law, i.e. stationary, non-stationary and complete. The results of calculating the constant times of the hot-wire anemometer thread τп and τтп of the moving heat flow, respectively, were τп = 0.59 s and τтп = 0.6 s, the time constant of the hot-wire anemometer is practically commensurate with the thermal time constant of the moving stream blowing over the nut raw material. It consists in the fact that the theoretical position of the hot-wire anemometer has been further developed in the direction of researching the characteristics of the thermal transient process of processing nut raw materials, all this makes it possible to determine the ranges of changes in the signals of the thermal device, which correspond to the ranges of change in the informative characteristics of the moving heat flow, and also allows the selection measuring equipment, establish rational operating modes of hot-wire anemometers and automated devices that use them in accordance with errors and sensitivities. The proposed algorithms for determining the informative parameters of the heat flow in the study of the transient process of heat transfer from the moving air flow to the sensitive element of the transducer, the results of the errors in measuring the velocity V of the moving heat flow, make it possible to calculate, design and create measuring automated devices that use hot-wire anemometers in food and processing industry, instrument making and chemical engineering.

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7

Kit, E., A. Cherkassky, T. Sant, and H. J. S. Fernando. "In Situ Calibration of Hot-Film Probes Using a Collocated Sonic Anemometer: Implementation of a Neural Network." Journal of Atmospheric and Oceanic Technology 27, no. 1 (January 1, 2010): 23–41. http://dx.doi.org/10.1175/2009jtecha1320.1.

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Abstract Although the integral quantities of atmospheric turbulence are conveniently measured using sonic anemometers, obtaining relevant finescale variables such as the kinetic energy dissipation using conventional hot-film/wire techniques remains a challenge because of two main difficulties. The first difficulty is the mean wind variability, which causes violation of the requirement that mean winds have a specific alignment with the hot-film/wire probe. To circumvent this problem, a combination of collocated sonic and hot-film anemometers, with the former measuring mean winds and aligning the latter in the appropriate wind direction via an automated platform, is successfully designed and implemented. The second difficulty is the necessity of frequent and onerous calibrations akin to hot-film anemometry that lead to logistical difficulties during outdoor (field) measurements. This is addressed by employing sonic measurements to calibrate the hot films in the same combination, with the output (velocity) to input (voltage) transfer function for the hot film derived using a neural network (NN) model. The NN is trained using low-pass-filtered hot-film and sonic data taken in situ. This new hot-film calibration procedure is compared with the standard calibration method based on an external calibrator. It is inferred that the sonic-based NN method offers great potential as an alternative to laborious standard calibration techniques, particularly in the laboratory and in stable atmospheric boundary layer settings. The NN approximation technique is found to be superior to the conventionally used polynomial fitting methods when used in conjunction with unevenly spaced calibration velocity data generated by sonic anemometers.

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8

Ligęza, Paweł. "Constant-Temperature Anemometer Bandwidth Shape Determination for Energy Spectrum Study of Turbulent Flows." Energies 14, no. 15 (July 25, 2021): 4495. http://dx.doi.org/10.3390/en14154495.

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Due to their common occurrence and fundamental role in human-realized processes and natural phenomena, turbulent flows are subject to constant research. One of the research tools used in these studies are hot-wire anemometers. These instruments allow for measurements in turbulent flows in a wide range of both velocities and frequencies of fluctuations. This article describes a new indirect method of determining the bandwidth shape of a constant-temperature anemometer. The knowledge of this bandwidth is an important factor in the study of the energy spectrum of turbulent flows.

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9

Crowell G. Bowers, Jr., Daniel H. Willits, and Henry D. Bowen. "Comparison of Temperature Correction Methods for Hot Wire Anemometers." Transactions of the ASAE 31, no. 5 (1988): 1552–55. http://dx.doi.org/10.13031/2013.30899.

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10

Uddin, Nezam, Guigen Liu, Qiwen Sheng, and Ming Han. "Constant temperature operation of fiber-optic hot-wire anemometers." Optics Letters 44, no. 10 (May 15, 2019): 2578. http://dx.doi.org/10.1364/ol.44.002578.

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11

Abdel-Rahman, A. A. "On the yaw-angle characteristics of hot-wire anemometers." Flow Measurement and Instrumentation 6, no. 4 (October 1995): 271–78. http://dx.doi.org/10.1016/0955-5986(95)00014-3.

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12

Proença, A. R., O. De almeida, and R. H. Self. "AERODYNAMICS AND AEROACOUSTICS SURVEY FOR A LOW SPEED SUBSONIC JET OPERATING AT MACH 0.25." Revista de Engenharia Térmica 13, no. 2 (December 31, 2014): 33. http://dx.doi.org/10.5380/reterm.v13i2.62092.

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The purpose of this work is to study and characterize, in laboratory, the aerodynamics of a free jet operating at subsonic regime and identify its acoustic signature. This study aims to analyze the fundamental role of turbulent flow structures in the total noise produced at different Mach numbers. This work is focused at low speed subsonic jets operating at Mach number 0.25. The research is done by analyzing the data obtained in experiments using Pitot tube, hot-wire anemometer and acoustic measurements. This work also describes the experimental procedures for each step of analysis, as well as the characteristics of jet noise facility. The data from measurements with Pitot tube is used to study the mean velocity profiles. The average properties are also analyzed with anemometry system, likewise used to study the turbulent intensity of eleven axial lines, ranging from the center line to the edge of the nozzle (lipline). These results are compared with the literature and is verified the accuracy of hot-wire anemometers for turbulent intensities lower than 15%. A database with the sound pressure level as a function of frequency is constructed from experiments serving as data for further numerical analysis to solve this problem.

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13

Freymuth, Peter. "On higher order dynamics of constant-temperature hot-wire anemometers." Measurement Science and Technology 9, no. 3 (March 1, 1998): 534–35. http://dx.doi.org/10.1088/0957-0233/9/3/031.

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14

Özahi, Emrah, Melda Özdinç Çarpınlıoǧlu, and Mehmet Yaşar Gündoǧdu. "Simple methods for low speed calibration of hot-wire anemometers." Flow Measurement and Instrumentation 21, no. 2 (June 2010): 166–70. http://dx.doi.org/10.1016/j.flowmeasinst.2010.02.004.

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15

Avallone, Elson, Paulo Mioralli, Pablo Natividade, Paulo Palota, Costa da, Jonas Antonio, and Verdério Aparecido. "An inexpensive anemometer using Arduino board." Facta universitatis - series: Electronics and Energetics 32, no. 3 (2019): 359–68. http://dx.doi.org/10.2298/fuee1903359a.

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In all studies involving wind speed, such as meteorology, wind turbines and agriculture accurate speed information for decision making is required. There are several types of anemometers, with medium and high costs, such as cup, hot wire and pitot tubes, the hot wire being more sensitive and expensive than others. The device developed in this work is the cup anemometer, that is easy to build. The great advantage of this device is the low cost, with an approximate value of US$ 50.00, using simple materials that are easy to find in commercial stores. The Reed Switch sensor is also another advantage as it does not require a sophisticated programming, as well as the open platform Arduino. The use of theoretical aerodynamic drag coefficients and the presented calculations resulted in values very close to a commercial anemometer. The coefficient of determination between the cup Anemometer and the standard sensor of Meteorological Research Institute IPMet/Brazil is R2=0.9999, indicating strong correlation between the instruments. As the reference anemometer (IPMet) has high embedded technology and the prototype is low cost, we conclude that the project has an attractive cost benefit for possible development and production, reaching the objective of this work.

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16

Hultmark, Marcus, and Alexander J. Smits. "Temperature corrections for constant temperature and constant current hot-wire anemometers." Measurement Science and Technology 21, no. 10 (August 13, 2010): 105404. http://dx.doi.org/10.1088/0957-0233/21/10/105404.

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17

Povkh, I. L., P. I. Savostenko, and Yu D. Ukrainskii. "Measurement of moist air velocity by means of hot-wire anemometers." Journal of Engineering Physics 48, no. 3 (March 1985): 280–84. http://dx.doi.org/10.1007/bf00878191.

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18

Filippov, V. M., O. V. Veselkova, and V. I. Dmitrieva. "Thin-foil and filament sensors of stick-on hot-wire anemometers." Measurement Techniques 37, no. 3 (March 1994): 303–7. http://dx.doi.org/10.1007/bf02614269.

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19

Durst, Franz, Jun-Mei Shi, and Michael Breuer. "Numerical Prediction of Hot-Wire Corrections Near Walls." Journal of Fluids Engineering 124, no. 1 (September 13, 2001): 241–50. http://dx.doi.org/10.1115/1.1429636.

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A thorough numerical investigation was performed for the two-dimensional convective heat transfer of a circular cylinder in a Couette flow close to a wall in order to study the hot-wire near-wall correction. A finite-volume Navier-Stokes solver enhanced by local block refinement and multigrid acceleration guaranteed highly accurate and efficient computational results. Unlike all previous numerical simulations, a more realistic model was used in the present study by taking the heat transfer in the solid wall into account to bridge the discrepancy between the previous theoretical models and the real situation. The computed results from the present investigation show good agreement with experimental data in the literature. Reference correction curves for hot-wire anemometers with respect to different wall materials (e.g., aluminum, glass, Perspex, air, etc.) were obtained.

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20

Siebert, Holger, Katrin Lehmann, and Raymond A. Shaw. "On the Use of Hot-Wire Anemometers for Turbulence Measurements in Clouds." Journal of Atmospheric and Oceanic Technology 24, no. 6 (June 2007): 980–93. http://dx.doi.org/10.1175/jtech2018.1.

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The use of a hot-wire anemometer for high-resolution turbulence measurements in a two-phase flow (e.g., atmospheric clouds) is discussed. Experiments in a small wind tunnel (diameter of 0.2 and 2 m in length) with a mean flow velocity in the range between 5 and 16 m s−1 are performed. In the wind tunnel a spray with a liquid water content of 0.5 and 2.5 g m−3 is generated. After applying a simple despiking algorithm, power spectral analysis shows the same results as spectra observed without spray under similar flow conditions. The flattening of the spectrum at higher frequencies due to impacting droplets could be reduced significantly. The time of the signal response of the hot wire to impacting droplets is theoretically estimated and compared with observations. Estimating the fraction of time during which the velocity signal is influenced by droplet spikes, it turns out that the product of liquid water content and mean flow velocity should be minimized. This implies that for turbulence measurements in atmospheric clouds, a slowly flying platform such as a balloon or helicopter is the appropriate instrumental carrier. Examples of hot-wire anemometer measurements with the helicopter-borne Airborne Cloud Turbulence Observation System (ACTOS) are presented.

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21

Обух, Ірина Ярославівна, Юрій Васильович Яцук, and Тарас Михайлович Олеськів. "Ambient temperature-invariant hot-wire anemometers for the construction of gas meters." Eastern-European Journal of Enterprise Technologies 4, no. 9(70) (July 18, 2014): 10. http://dx.doi.org/10.15587/1729-4061.2014.26271.

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22

Freymuth, P. "Second or third order control theory for constant-temperature hot-wire anemometers?" Experiments in Fluids 23, no. 2 (June 13, 1997): 175–76. http://dx.doi.org/10.1007/s003480050099.

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23

Kegerise, M. A., and E. F. Spina. "A comparative study of constant-voltage and constant-temperature hot-wire anemometers." Experiments in Fluids 29, no. 2 (August 7, 2000): 154–64. http://dx.doi.org/10.1007/s003489900073.

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24

Kegerise, M. A., and E. F. Spina. "A comparative study of constant-voltage and constant-temperature hot-wire anemometers:." Experiments in Fluids 29, no. 2 (August 7, 2000): 165–77. http://dx.doi.org/10.1007/s003489900074.

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25

Fan, Dewei, Cheng Xiaoqi, Chi Wai Wong, and Jun-De Li. "Optimization and Determination of the Frequency Response of Constant-Temperature Hot-Wire Anemometers." AIAA Journal 55, no. 8 (June 2017): 2537–43. http://dx.doi.org/10.2514/1.j055801.

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26

Pappas, I., Th Laopoulos, S. Vlassis, and S. Siskos. "Current Mode Interfacing Circuit for Flow Sensing Based on Hot-Wire Anemometers Technique." Procedia Engineering 25 (2011): 1601–4. http://dx.doi.org/10.1016/j.proeng.2011.12.396.

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27

Tewari, S. S., and Y. Jaluria. "Calibration of constant‐temperature hot‐wire anemometers for very low velocities in air." Review of Scientific Instruments 61, no. 12 (December 1990): 3834–45. http://dx.doi.org/10.1063/1.1141510.

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28

Robinson, Allen L., and Richard G. Sextro. "A Novel Technique to Measure the Magnitude and Direction of Flow in a Tube." Journal of Fluids Engineering 122, no. 1 (November 30, 1999): 186–88. http://dx.doi.org/10.1115/1.483249.

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This paper describes a novel in-line sensor that measures the magnitude and direction of gas flow in a tube. The sensor possesses a unique set of performance characteristics: low detection limit, little resistance to flow, and directional sensitivity. The sensor consists of two hot wire anemometers mounted in a U-shaped tube. Differences in the signals between the two hot wires under low velocity conditions are used to determine the direction of the flow. Calibration curves of flow rate versus measured velocity are used to determine the magnitude of the flow. The sensor has applications in systems that are characterized by naturally driven oscillating flows. [S0098-2202(00)02701-2]

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29

Ardekani, M. A., and F. Farhani. "Experimental study on response of hot wire and cylindrical hot film anemometers operating under varying fluid temperatures." Flow Measurement and Instrumentation 20, no. 4-5 (August 2009): 174–79. http://dx.doi.org/10.1016/j.flowmeasinst.2009.06.001.

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30

Graham, L. J. W., and K. Bremhorst. "A linear compensation technique for inclined hot-wire anemometers subjected to fluid temperature changes." Measurement Science and Technology 1, no. 12 (December 1, 1990): 1322–25. http://dx.doi.org/10.1088/0957-0233/1/12/011.

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31

Marius Alexandru, PANAIT. "Investigation on Characterizing Heated Pulsating Flows with Hot Wire Anemometers - A Hands-On Approach." INCAS BULLETIN 6, no. 2 (June 13, 2014): 95–101. http://dx.doi.org/10.13111/2066-8201.2014.6.2.9.

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32

Tsakanian, Oleh S., and Serhii V. Koshel. "Integral Thermo-Anemometers for Average Temperature and Airflow Measurement in Ducts, at Anemostat Outlets and in Ventilation Grilles." Journal of Mechanical Engineering 23, no. 4 (December 30, 2020): 14–21. http://dx.doi.org/10.15407/pmach2020.04.014.

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When creating ventilation systems, it is important to correctly calculate the volumes of air inflow and outflow. If an error is made in the calculation or a redistribution of air flows is required, measurements are indispensable. The existing methods for determining the air flow rate by using point measurements in the cross-section are laborious and time-consuming, and taking readings at different time points introduces a significant error into the result. A. M. Pidhornyi Institute of Mechanical Engineering Problems of the National Academy of Sciences of Ukraine has developed a new hot-wire anemometer whose use greatly simplifies the measuring process. This device allows one to measure the average values of temperature and air velocity (flow rate) in the cross-section of air ducts or at the inlets and outlets of grilles and anemostats, and can be used in real time to monitor and control air flow rate and temperature in ventilation systems. The probe of the hot-wire anemometer is a metal shell with guides on which a sensitive element is laid. Its principle of operation is to change the heat transfer coefficient at different air leakage velocities. The anemometer is preliminarily calibrated in laboratory conditions at various velocities. There has been obtained a calibration dependence that can be used to measure the air flow rate at the inlets and outlets of air distribution devices and directly in the air ducts. To improve the measurement accuracy, it is necessary to provide the 90° angle of airflow leakage on the hot-wire anemometer probe. For this, special air collectors and air flow rectifiers are used.

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33

Sherif, S. A., and R. H. Pletcher. "An analytical procedure for predicting the response of constant-temperature hot-wire and film anemometers." Measurement 25, no. 3 (April 1999): 193–201. http://dx.doi.org/10.1016/s0263-2241(99)00003-2.

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34

Guellouz, M. S., and S. Tavoularis. "A simple pendulum technique for the calibration of hot-wire anemometers over low-velocity ranges." Experiments in Fluids 18, no. 3 (January 1995): 199–203. http://dx.doi.org/10.1007/bf00230265.

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35

Maruca, Bennett A., Raffaele Marino, David Sundkvist, Niharika H. Godbole, Stephane Constantin, Vincenzo Carbone, and Herb Zimmerman. "Overview of and first observations from the TILDAE High-Altitude Balloon Mission." Atmospheric Measurement Techniques 10, no. 4 (April 26, 2017): 1595–607. http://dx.doi.org/10.5194/amt-10-1595-2017.

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Abstract. Though the presence of intermittent turbulence in the stratosphere has been well established, much remains unknown about it. In situ observations of this phenomenon, which have provided the greatest details of it, have mostly been achieved via sounding balloons (i.e., small balloons which burst at peak altitude) carrying constant-temperature hot-wire anemometers (CTAs). The Turbulence and Intermittency Long-Duration Atmospheric Experiment (TILDAE) was developed to test a new paradigm for stratospheric observations. Rather than flying on a sounding balloon, TILDAE was incorporated as an add-on experiment to the payload of a NASA long-duration balloon mission that launched in January 2016 from McMurdo Station, Antarctica. Furthermore, TILDAE's key instrument was a sonic anemometer, which (relative to a CTA) provides better-calibrated measurements of wind velocity and a more robust separation of velocity components. During the balloon's ascent, TILDAE's sonic anemometer provided atmospheric measurements up to an altitude of about 18 km, beyond which the ambient air pressure was too low for the instrument to function properly. Efforts are currently underway to scientifically analyze these observations of small-scale fluctuations in the troposphere, tropopause, and stratosphere and to develop strategies for increasing the maximum operating altitude of the sonic anemometer.

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36

Weiss, Julien. "Effect of bridge imbalance on the estimation of sensitivity coefficients for constant-temperature hot-wire anemometers." Measurement Science and Technology 14, no. 8 (July 16, 2003): 1373–80. http://dx.doi.org/10.1088/0957-0233/14/8/324.

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37

Yang, Yingchen, Douglas L. Jones, and Chang Liu. "Recovery of rectified signals from hot-wire/film anemometers due to flow reversal in oscillating flows." Review of Scientific Instruments 81, no. 1 (January 2010): 015104. http://dx.doi.org/10.1063/1.3277109.

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38

Lundström, Hans. "Investigation of heat transfer from thin wires in air and a new method for temperature correction of hot-wire anemometers." Experimental Thermal and Fluid Science 128 (October 2021): 110403. http://dx.doi.org/10.1016/j.expthermflusci.2021.110403.

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39

Weiss, J., H. Knauss, and S. Wagner. "Method for the determination of frequency response and signal to noise ratio for constant-temperature hot-wire anemometers." Review of Scientific Instruments 72, no. 3 (2001): 1904. http://dx.doi.org/10.1063/1.1347970.

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40

Bodini, Nicola, Julie K. Lundquist, and Rob K. Newsom. "Estimation of turbulence dissipation rate and its variability from sonic anemometer and wind Doppler lidar during the XPIA field campaign." Atmospheric Measurement Techniques 11, no. 7 (July 20, 2018): 4291–308. http://dx.doi.org/10.5194/amt-11-4291-2018.

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Abstract. Despite turbulence being a fundamental transport process in the boundary layer, the capability of current numerical models to represent it is undermined by the limits of the adopted assumptions, notably that of local equilibrium. Here we leverage the potential of extensive observations in determining the variability in turbulence dissipation rate (ϵ). These observations can provide insights towards the understanding of the scales at which the major assumption of local equilibrium between generation and dissipation of turbulence is invalid. Typically, observations of ϵ require time- and labor-intensive measurements from sonic and/or hot-wire anemometers. We explore the capability of wind Doppler lidars to provide measurements of ϵ. We refine and extend an existing method to accommodate different atmospheric stability conditions. To validate our approach, we estimate ϵ from four wind Doppler lidars during the 3-month XPIA campaign at the Boulder Atmospheric Observatory (Colorado), and we assess the uncertainty of the proposed method by data intercomparison with sonic anemometer measurements of ϵ. Our analysis of this extensive dataset provides understanding of the climatology of turbulence dissipation over the course of the campaign. Further, the variability in ϵ with atmospheric stability, height, and wind speed is also assessed. Finally, we present how ϵ increases as nocturnal turbulence is generated during low-level jet events.

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Addison, J. S., and H. P. Hodson. "Modeling of Unsteady Transitional Boundary Layers." Journal of Turbomachinery 114, no. 3 (July 1, 1992): 580–89. http://dx.doi.org/10.1115/1.2929182.

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In turbomachinery, a considerable proportion of the blade surface area can be covered by transitional boundary layers. This means that accurate prediction of the profile loss and boundary layer behavior in general depends on the accurate modeling of the transitional boundary layers, especially at low Reynolds numbers. This paper presents a model for determining the intermittency resulting from the unsteady transition caused by the passage of wakes over a blade surface. The model is founded on work by Emmons (1951) who showed that the intermittency could be calculated from a knowledge of the behavior of randomly formed turbulent spots. The model Is used to calculate the development of the boundary layer on the rotor of a low Reynolds number single-stage turbine. The predictions are compared with experimental results obtained using surface-mounted hot-film anemometers and hot-wire traverses of the rotor midspan boundary layer at two different rotor-stator gaps. The validity and limitations of the model are discussed.

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Bechert, D. W., and B. Stahl. "Excitation of instability waves in free shear layers Part 2. Experiments." Journal of Fluid Mechanics 186 (January 1988): 63–84. http://dx.doi.org/10.1017/s0022112088000047.

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The acoustical excitation of shear layers is investigated experimentally. Acoustical excitation causes, for example, the so-called ‘orderly structures’ in shear layers and jets. Also, the deviations in the spreading rate between different turbulent-shear-layer experiments are due to the same excitation mechanism. The present investigations focus on measurements in the linear interaction region close to the edge from which the shear layer is shed. We report on two sets of experiments (Houston 1981 and Berlin 1983/84). The measurements have been carried out with laminar shear layers in air using hot-wire anemometers and microphones. The agreement between these measurements and the theory is good. Even details of the fluctuating flow field correspond to theoretical predictions, such as the local occurrence of negative phase speeds.

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Zhang, Binglong, He Liu, Yangyang Li, Hui Liu, and Jinzhong Dong. "Experimental Study of Coaxial Jets Mixing Enhancement Using Synthetic Jets." Applied Sciences 11, no. 2 (January 15, 2021): 803. http://dx.doi.org/10.3390/app11020803.

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Synthetic jets perpendicular to the mainstream have been used to experimentally study the coaxial jets mixing enhancement in this paper. The parameters of coaxial jets such as vorticity, streamwise velocity, radial velocity, Reynolds shear stress, and turbulence intensity are measured using the particle image velocimetry (PIV) and hot wire anemometers. The distribution characteristics of these parameters with and without synthetic jets were obtained. The mechanism of coaxial jets mixing enhancement using synthetic jets was summarized by analyzing these experimental results, and it was also found that the momentum coefficient was the most critical factor for jets mixing enhancement. The comparative experiments fully verified the mechanism, showing that with an appropriate momentum coefficient, the synthetic jets significantly enhanced coaxial jets mixing.

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Yen, S. C., and S. F. Wu. "Square-Cylinder Flow Characteristics Modulated Using Upstream Control Rod." Journal of Mechanics 28, no. 2 (May 8, 2012): 279–89. http://dx.doi.org/10.1017/jmech.2012.31.

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AbstractThe flow patterns, vortex-shedding frequency and aerodynamic performance of the square-cylinder flow were modulated using an upstream control rod. Additionally, the flow behaviors were examined using various Reynolds numbers, rotation angles, and spacing ratios. The flow patterns were visualized using the smoke-wire scheme. The global velocity fields and streamline patterns were analyzed using the particle image velocimetry (PIV). Additionally, the flow modes were characterized based on the kinematics theory. Moreover, the vortex-shedding frequencies behind upstream control rod and the square cylinder were detected using two hot-wire anemometers. The surface pressure on square cylinder was determined using a linear pressure scanner. Then, the aerodynamic parameters were calculated using the surface-pressure profiles. Three characteristic flow modes — single, attached, and bi-vortex-street — were categorized by varying the Reynolds number and spacing ratio. In the attached mode, the position of upstream control rod determined the flow characteristics. Furthermore, in the attached mode, the mean drag force of the square cylinder is about 57% lower than of single-square cylinder.

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Mauderly, Joe L. "Measurement of Respiration and Respiratory Responses During Inhalation Exposures." Journal of the American College of Toxicology 9, no. 4 (July 1990): 397–405. http://dx.doi.org/10.3109/10915819009078750.

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This report reviews approaches for making measurements of the respiration of subjects during inhalation exposures. Respiration is measured to quantitate the volume of exposure material inhaled, to evaluate the normalcy and steadiness of respiration during exposure, to relate breathing pattern to deposition or uptake of inhaled materials, to detect physiological responses to inhaled materials, and to monitor respiration during controlled breathing. A small number of basic devices are commonly used during exposures, including nonrebreathing valves, pneumotachographs, spirometers, and plethysmographs. Less frequently used devices adaptable for use during exposures include hot wire anemometers, respiratory-inductive plethysmographs, and impedance pneumographs. These devices, some of their potential uses, and their advantages and disadvantages are described and useful references are given. Several useful combinations of respiratory measurement devices are suggested for low-volume, bag-to-bag, and immersion exposure systems.

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Ainsworth, R. W., J. L. Allen, and J. J. M. Batt. "The Development of Fast Response Aerodynamic Probes for Flow Measurements in Turbomachinery." Journal of Turbomachinery 117, no. 4 (October 1, 1995): 625–34. http://dx.doi.org/10.1115/1.2836581.

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The advent of a new generation of transient rotating turbine simulation facilities, where engine values of Reynolds and Mach number are matched simultaneously together with the relevant rotational parameters for dimensional similitude (Dunn et al., 1988; Epstein and Guenette, 1984; Ainsworth et al., 1988), has provided the stimulus for developing improved instrumentation for investigating the aerodynamic flows in these stages. Much useful work has been conducted in the past using hot-wire and laser anemometers. However, hot-wire anemometers are prone to breakage in the high-pressure flows required for correct Reynolds numbers. Furthermore, some laser techniques require a longer run-time than these transient facilities permit, and generally yield velocity information only, giving no data on loss production. Advances in semiconductor aerodynamic probes are beginning to fulfill this perceived need. This paper describes advances made in the design, construction, and testing of two and three-dimensional fast response aerodynamic probes, where semiconductor pressure sensors are mounted directly on the surface of the probes, using techniques that have previously been successfully used on the surface of rotor blades (Ainsworth et al., 1991). These are to be used to measure Mach number and flow direction in compressible unsteady flow regimes. In the first section, a brief review is made of the sensor and associated technology that has been developed to permit a flexible design of fast response aerodynamic probe. Following this, an extensive program of testing large-scale aerodynamic models of candidate geometries for suitable semiconductor scale probes is described, and the results of these discussed. The conclusions of these experiments, conducted for turbine representative mean and unsteady flows, yielded new information for optimizing the design of the small-scale semiconductor probes, in terms of probe geometry, sensor placement, and aerodynamic performance. Details are given of a range of wedge and pyramid semiconductor probes constructed, and the procedures used in calibrating and making measurements with them. Differences in performance are discussed, allowing the experimenter to choose an appropriate probe for the particular measurement required. Finally, the application of prototype semiconductor probes in a transient rotor experiment at HP turbine representative conditions is described, and the data so obtained are compared with CFD solutions of the unsteady viscous flow-field.

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Raupach, MR, and JF Leys. "Aerodynamics of a portable wind erosion tunnel for measuring soil erodibility by wind." Soil Research 28, no. 2 (1990): 177. http://dx.doi.org/10.1071/sr9900177.

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Portable wind erosion tunnels must satisfy several aerodynamic criteria to ensure that the flow within them acceptably reproduces the atmospheric flow causing natural wind erosion. We define these criteria and use them to assess the flow and turbulence in two alternative designs of portable wind erosion tunnel: the first has a working section with an approximately triangular, 'tent-shaped' cross section, while the second has a conventional, rectangular working section. The measurements were made with Pitot-static tubes and X-configuration hot-wire anemometers, over stable (non-eroding) rough surfaces, mainly mowed grass of height 1 cm. We found that, with careful attention to flow conditioning elements such as honeycombs and tripping fences, an acceptable flow can be achieved in the rectangular tunnel. The flow in the tent-shaped tunnel is less satisfactory, exhibiting departures from the logarithmic wind profile law which depend on the surface roughness.

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Wildmann, Norman, Nicola Bodini, Julie K. Lundquist, Ludovic Bariteau, and Johannes Wagner. "Estimation of turbulence dissipation rate from Doppler wind lidars and in situ instrumentation for the Perdigão 2017 campaign." Atmospheric Measurement Techniques 12, no. 12 (December 5, 2019): 6401–23. http://dx.doi.org/10.5194/amt-12-6401-2019.

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Abstract. The understanding of the sources, spatial distribution and temporal variability of turbulence in the atmospheric boundary layer, and improved simulation of its forcing processes require observations in a broad range of terrain types and atmospheric conditions. In this study, we estimate turbulence kinetic energy dissipation rate ε using multiple techniques, including in situ measurements of sonic anemometers on meteorological towers, a hot-wire anemometer on a tethered lifting system and remote-sensing retrievals from a vertically staring lidar and two lidars performing range–height indicator (RHI) scans. For the retrieval of ε from the lidar RHI scans, we introduce a modification of the Doppler spectral width method. This method uses spatiotemporal averages of the variance in the line-of-sight velocity and the turbulent broadening of the Doppler backscatter spectrum. We validate this method against the observations from the other instruments, also including uncertainty estimations for each method. The synthesis of the results from all instruments enables a detailed analysis of the spatial and temporal variability in ε across a valley between two parallel ridges at the Perdigão 2017 campaign. We analyze in detail how ε varies in the night from 13 to 14 June 2017. We find that the shear zones above and below a nighttime low-level jet experience turbulence enhancements. We also show that turbulence in the valley, approximately 11 rotor diameters downstream of an operating wind turbine, is still significantly enhanced by the wind turbine wake.

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Kiełbasa, Jan. "The Hot-Wire Anemometer/Anemometr Z Grzanym Włóknem." Archives of Mining Sciences 59, no. 2 (June 1, 2014): 467–75. http://dx.doi.org/10.2478/amsc-2014-0033.

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Abstract This study analyses the behaviour of a hot-wire anemometer incorporated into a bridge circuit in the function of the voltage Uz supplying the bridge circuit and hence the current Iw flowing through the hot wire. The dependence of differential voltage ΔU on Iw and the value of derivative d(ΔU)/dIw as a function of the current supplying the hot-wire element were determined. These data enable the determination of working conditions of the constant-resistance (i.e. the constant-temperature) hot-wire anemometer.

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Goto, Takahisa, Hayato Saito, Yoshinori Nakata, Shoichi Uezono, Fumito Ichinose, Masanori Uchiyama, and Shigeho Morita. "Effects of Xenon on the Performance of Various Respiratory Flowmeters." Anesthesiology 90, no. 2 (February 1, 1999): 555–63. http://dx.doi.org/10.1097/00000542-199902000-00032.

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Background The anesthetic gas xenon has distinctly different physical properties compared with air, nitrous oxide, or oxygen. This led us to predict that xenon would affect the performance of commercially available flowmeters. Methods Flow was generated by an anesthesia ventilator connected to a lung simulator via a semiclosed breathing circuit. With the system filled with air or with various concentrations of xenon or nitrous oxide in a balance of oxygen, the tidal volume was measured with two rotating vanes, a Pitot tube, a variable-orifice flowmeter, and two constant-temperature hot-wire flowmeters. Results Although xenon minimally affected both rotating vane flowmeters, it caused the Pitot tube and the variable-orifice flowmeters to overread in proportion to the square root of the density of the gas mixture used (xenon is 4.6 times more dense than air). In contrast, the hot-wire anemometers underread with xenon; for example, their readings in the presence of 45% and 70% xenon were less than 10% of those displayed when air was used. Nitrous oxide minimally affected all the flowmeters except the variable-orifice device. The Pitot flowmeter was also affected, but only when its gas analyzer port was open to the ambient air so that it no longer corrected its readings for changes in gas composition. In these cases, nitrous oxide produced overreadings in the same manner as did xenon. Conclusion Among the four types of flowmeters studied, only the rotating-vane type is sufficiently accurate for use during anesthesia with xenon.

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