Calibration of Constant-Temperature Hot-Wire Anemometers at Low Velocities in Water with Variable Fluid Temperature

1972 ◽  
Vol 94 (1) ◽  
pp. 17-22 ◽  
Author(s):  
K. Hollasch ◽  
B. Gebhart
Keyword(s):  
Experimental Study ◽  
Natural Convection ◽  
Constant Temperature ◽  
Fluid Temperature ◽  
Hot Wire ◽  
Temperature Variations ◽  
Wire Probe ◽  
Temperature Mode

Calibration of hot-wire probes operated in a constant-temperature mode in water at low velocities is discussed. Operation under circumstances where natural convection effects are important is considered. A method of calibrating a constant-temperature hot-wire probe for variations in fluid temperature is presented. The method consists of varying wire overheat during calibration at a constant fluid temperature. A relation is derived analytically relating anemometer output with a variable overheat resistance to anemometer output with fluid temperature variations. An experimental study to verify the analysis is presented.

scholarly journals Simplified Calibration Method for Constant-Temperature Hot-Wire Anemometry

2020 ◽  
Vol 10 (24) ◽  
pp. 9058
Author(s):  
Hidemi Takahashi ◽  
Mitsuru Kurita ◽  
Hidetoshi Iijima ◽  
Seigo Koga
Keyword(s):  
Boundary Layer ◽  
Flow Velocity ◽  
Constant Temperature ◽  
Calibration Method ◽  
Large Temperature ◽  
Velocity Data ◽  
Hot Wire ◽  
Temperature Variations ◽  
Wire Temperature ◽  
Hot Wire Anemometry

This study proposes a unique approach to convert a voltage signal obtained from a hot-wire anemometry to flow velocity data by making a slight modification to existing temperature-correction methods. The approach was a simplified calibration method for the constant-temperature mode of hot-wire anemometry without knowing exact wire temperature. The necessary data are the freestream temperature and a set of known velocity data which gives reference velocities in addition to the hot-wire signal. The proposed method was applied to various boundary layer velocity profiles with large temperature variations while the wire temperature was unknown. The target flow velocity was ranged between 20 and 80 m/s. By using a best-fit approach between the velocities in the boundary layer obtained by hot-wire anemometry and by the pitot-tube measurement, which provides reference data, the unknown wire temperature was sought. Results showed that the proposed simplified calibration approach was applicable to a velocity range between 20 and 80 m/s and with temperature variations up to 15 °C with an uncertainty level of 2.6% at most for the current datasets.

Self-Aligning Hot-Wire Probe

1967 ◽  
Vol 71 (681) ◽  
pp. 657-658 ◽  
Author(s):  
A. D. Bond ◽  
A. M. Porter
Keyword(s):  
Constant Temperature ◽  
Two Dimensional ◽  
Servo Motor ◽  
Hot Wire ◽  
Turbulence Measurements ◽  
Wire Probe ◽  
Two Dimensional Flow ◽  
The Wire ◽  
Single Constant ◽  
Stream Direction

Summary:—This note describes how a single constant temperature hot wire may be used for measurements of direction, velocity and turbulence in a two-dimensional flow. The wire probe is rotated by a servo motor which automatically sets the wire with its axis either in the stream direction or normal to the flow. The accuracy of setting the wire in the direction of the stream is about , and across the stream is about 1°. If the higher accuracy is demanded the velocity and turbulence measurements require a second setting of the probe, at 90° to the previous one. When less precision is acceptable, the angle, velocity and turbulence measurements may be taken at the single setting, normal to the stream.

Dynamic and Static Characteristics Analysis Study of Hot-Wire Probe in Constant Temperature Model

2013 ◽  
Vol 278-280 ◽  
pp. 735-742
Author(s):  
Qing Yan Wei ◽  
Tian Hong Zhang
Keyword(s):  
Heat Conduction ◽  
Constant Temperature ◽  
Temperature Model ◽  
Static Characteristics ◽  
Hot Wire ◽  
Wire Probe ◽  
Balance Principle ◽  
Characteristics Analysis ◽  
Control Circuits ◽  
Improved Design

Lumped and distributed dynamic/static models of constant temperature hot-wire probe are established according to heat balance principle. Dynamic and static characteristics of hot-wire probe are analyzed in terms of hot-wire probe sizes, control circuit parameters and flow velocity.Simulation results show that reliability and stability of the hot-wire probe depend on bias voltage.The dynamic and static characteristics of hot-wire probe refly on the ratio of length to diameter ratio crucially.Once the ratio exceeds 300, heat conduction terminal loss can be ignored. When over-heating ratio of hot- wire or flow velocity increases, heat conduction terminal loss can be omitted as well .Besides frequency response of hot-wire probe can be improved simultaneously.The above conclusions can provide guidance in the improved design for hot-wire probe and its control-circuits.

Some Corrections to the Linearized Response of a Constant-Temperature Hot-Wire Anemometer Operated in a Low-Speed Flow

1962 ◽  
Vol 29 (3) ◽  
pp. 554-558 ◽  
Author(s):  
W. G. Rose
Keyword(s):  
Shear Stress ◽  
Constant Temperature ◽  
Flow Direction ◽  
Turbulent Intensity ◽  
Order Effects ◽  
Fluid Temperature ◽  
Hot Wire ◽  
Mean Velocity ◽  
Low Speed ◽  
Speed Flow

An equation is obtained for the instantaneous response of a constant-temperature hot-wire anemometer having a linearized output. The result includes the second-order effects of variations in fluid temperature and in flow direction. Corrected equations for outputs in terms of mean velocity, turbulent-intensity components, and shear stress are derived from the instantaneous response.

Natural Convection From Horizontal Cylinders at Near-Critical Pressures—Part I: Experimental Study

2012 ◽  
Vol 135 (2) ◽  
Author(s):  
Yohann Rousselet ◽  
Gopinath R. Warrier ◽  
Vijay K. Dhir
Keyword(s):  
Heat Transfer ◽  
Experimental Study ◽  
Heat Transfer Coefficient ◽  
Natural Convection ◽  
Transfer Coefficient ◽  
Convection Heat Transfer ◽  
Bulk Temperature ◽  
Natural Convection Heat Transfer ◽  
Fluid Temperature ◽  
Convection Heat

An experimental study of free convection heat transfer from horizontal wires to carbon dioxide at near-critical pressures has been performed. In the experiments, platinum wires ranging in size from 25.4 μm to 100 μm and a nichrome 60/20 wire of 101.6 μm diameter were used. The pressure (P) and bulk temperature (Tb) of the fluid were varied in the range: 6.34 MPa ≤ P ≤ 9.60 MPa and 10 °C ≤ Tb ≤ 33.3 °C, respectively. The wall temperature (Tw) was systematically increased from Tb + 0.1 °C to 250 °C. Visual observations of the fluid flow were made using a high speed camera. The similarity between natural convection heat transfer at Tw < Tsat (for P < Pc) and Tw < Tpc (for P > Pc), as well as the similarity between film boiling at Tw > Tsat (for P < Pc) and natural convection heat transfer at Tw > Tpc (for P > Pc), was demonstrated. The dependence of the heat transfer coefficient on the wire diameter was found to be h ∝ D−0.5, for both P < Pc and P > Pc. The bulk fluid temperature is introduced as a new reference temperature for the calculation of fluid properties. Correlations have been developed to predict the natural convection heat transfer coefficient at both subcritical and supercritical pressures. The developed correlations predict almost all the experimental data from the current study and those reported in the literature to within ±15%.

Axisymmetrical Turbulent Swirling Natural-Convection Plume: Part 2—Experimental Investigation

1966 ◽  
Vol 33 (3) ◽  
pp. 656-661 ◽  
Author(s):  
Shao-Lin Lee
Keyword(s):  
Experimental Investigation ◽  
Natural Convection ◽  
Velocity Fields ◽  
Hot Wire ◽  
Ambient Fluid ◽  
Wire Probe ◽  
Characteristic Radius ◽  
Burner Flame ◽  
Theoretical Predictions ◽  
Temperature And Velocity Fields

An experimental investigation is made of the behavior of an axisymmetrical turbulent swirling natural-convection plume in an otherwise motionless ambient fluid. The swirling plume is issued from the exit of a swirling-plume generator which couples the hot gases from a Bunsen burner flame and the swirling mass of air from a ring of distributed tangential jets. Temperature and velocity fields of the swirling plume are measured by the use of a temperature-calibrated, V-shaped hot-wire probe. Measured results of the vertical and swirling velocities, the temperature, and the characteristic radius of the swirling plume are found to agree closely with the theoretical predictions of Part 1.

EXPERIMENTAL STUDY OF NATURAL CONVECTION IN A CAVITY: PRECISE VISUALIZATION METHOD OF TEMPERATURE FIELD

2018 ◽  
Author(s):  
Menghua Duan ◽  
Lin Chen ◽  
Yongchang Feng ◽  
Junnosuke Okajima ◽  
Atsuki Komiya
Keyword(s):  
Experimental Study ◽  
Temperature Field ◽  
Natural Convection ◽  
Visualization Method
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