Appraisal of a hot-wire temperature compensation technique for velocity measurements in non-isothermal flows

Ball, S J; Ashforth-Frost, S.; Jambunathan, K.; Whitney, C.F.

doi:10.1016/s0017-9310(98)00371-8

Cited by 12 publications

(8 citation statements)

References 12 publications

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“…which is a nonnegligible compensation of velocity signal E v through ambient flow temperature T a during the measurement of nonisothermal turbulent flow. 29,30 To further discuss the effect of temperature compensation on velocity signal under a certain change in temperatures, we present the error of output velocity of measurement without monitoring the real-time temperature change (case A) and with monitoring the real-time temperature change (case B) under a jet with given velocities (120, 140, 150 m/s) in Figure 2. It can be seen that the errors of case A and case B are approximately 2 and 0.095% per 1 °C change in ambient air temperature, respectively, which is in agreement with the estimation in previous reports.…”

Section: Measurementmentioning

confidence: 99%

“…An HWA probe with two wires is used to obtain the velocity signal and the real-time temperature at the same acquisition frequency, where both of the wires are with the same offsets from both the nozzle exit and the centerline, thus providing temporal and spatial consistency of the fluctuating velocity and temperature during the measurement. Upon simultaneous data acquisitions, the fluctuating velocity of each measuring point can be determined on the basis of the dependence of sensor velocity calibration on ambient temperature variation through the correlation which is a nonnegligible compensation of velocity signal E v through ambient flow temperature T a during the measurement of nonisothermal turbulent flow. , …”

Section: Experimental Setup and Hwa Measurementmentioning

confidence: 99%

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Simultaneous Measurement in Nonisothermal Melt-Blowing Airflow Field: Time-Averaged and Turbulent Characteristics

Yang

Zeng

2020

Ind. Eng. Chem. Res.

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Melt-blowing airflow, which involves converging jets of high-temperature and high-speed, is a nonisothermal turbulent flow. In this work, simultaneous velocity−temperature measurement has been accomplished for the first time to study the airflow under the nozzle of a melt-blowing slot die systematically. The timeaveraged characteristics and turbulence characteristics are presented. The evolution of velocity, temperature, and turbulence intensity reveals the features during the merging and combing process of the nonisothermal air jets. By analyzing the turbulence and the bending of fiber under nonisothermal and isothermal conditions, we find that the turbulence distribution pattern in nonisothermal conditions helps intensify the bending instability of fiber under the nozzle.

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Section: Measurementmentioning

confidence: 99%

Section: Experimental Setup and Hwa Measurementmentioning

confidence: 99%

Simultaneous Measurement in Nonisothermal Melt-Blowing Airflow Field: Time-Averaged and Turbulent Characteristics

Yang

Zeng

2020

Ind. Eng. Chem. Res.

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“…In non-isothermal flows, the responses of a hotwire to changes in velocity and temperature are indistinguishable. As a result, temperature contamination of the sensor leads to large errors in the measured velocity [16]. Even in isothermal flow conditions in which a hot-wire anemometer is used to measure air velocity, the fluid temperature may still be different from the calibration temperature, this temperature discrepancy also brings errors in velocity measurement [10].…”

Section: Introductionmentioning

confidence: 99%

A Calibration Facility for Hot-Wire Anemometers in Extremely Low Speed with Air Temperature and Humidity Variable and Controllable

Zhou,

Zhang,

Tian

et al. 2024

Applied Sciences

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Aimed at addressing the difficult problems existing in extremely low speed calibration facilities for hot-wire anemometers, where calibration accuracy is often insufficient and vulnerable to the contamination from temperature and humidity discrepancies between the calibration environment and the application environment, a calibration rig with a velocity range from 0.10 m/s to 1.0 m/s, an air temperature range from ambient temperature to 60 °C, and a humidity range from 20%RH to 80%RH was designed, developed, and constructed. The overall layout arrangement and the mechanical structure of the facility are illustrated. The master control system, the motion control system, the temperature and humidity control system are designed, tested and adjusted. The adjustment results are demonstrated and discussed. The analysis of the results reveals that the maximum velocity control error is 0.000989 m/s, satisfying the design target of 0.003 m/s; the corresponding maximum relative error is 0.241%, which is less than the design target of 0.4%; the maximum temperature control error is 0.9 °C, meeting the design target accuracy of 1 °C; the maximum humidity control error is 2.9%RH, which is below the design target of 4%RH. When the facility is applied to the calibration of a hot-wire anemometer, the maximum error of the fitting curves in modified King’s law is 0.02236 m/s, while that in Van der Hegge Zijnen’s formula is 0.023217 m/s, both of which satisfy the design target accuracy of 0.03 m/s. The maximum relative errors of fitting curves using the two formulas are 5.214% and 8.527%, respectively. Analysis of calibration data reveals that the discrepancy in temperature and humidity between application site and calibration site may bring errors that can reach up to 1.2676% per unit relative humidity discrepancy, and 5.672% per degree Celsius of temperature deviation, respectively.

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“…A lot of papers, among them [13][14][15][16][17], and even a special review [18] are devoted to the problem of compensating the velocity reading of a hot wire for varying fluid temperature. Broadly speaking, three variants of solving the problem are known: (1) manual adjustment of the hot resistance R w to compensate for changes in T a (obsolete), ( 2) automatic compensation using an additional temperature sensor incorporated into the Wheatstone bridge (a separate measurement of T a is not necessary), and (3) analytical correction using a hot-wire heat-transfer relationship (a separate measurement of T a is necessary, the hot-wire probe is operated at a fixed hot resistance R w ) [19][20][21].…”

Section: Introductionmentioning

confidence: 99%

Hot-wire measurements with automatic compensation of ambient temperature changes

Miheev¹,

Molochnikov²,

Kratirov³

et al. 2015

THERM SCI

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Appraisal of a hot-wire temperature compensation technique for velocity measurements in non-isothermal flows

Cited by 12 publications

References 12 publications

Simultaneous Measurement in Nonisothermal Melt-Blowing Airflow Field: Time-Averaged and Turbulent Characteristics

Simultaneous Measurement in Nonisothermal Melt-Blowing Airflow Field: Time-Averaged and Turbulent Characteristics

A Calibration Facility for Hot-Wire Anemometers in Extremely Low Speed with Air Temperature and Humidity Variable and Controllable

Hot-wire measurements with automatic compensation of ambient temperature changes

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