Investigation of heat transfer from thin wires in air and a new method for temperature correction of hot-wire anemometers

Heat transfer coefficients have often been experimentally measured, taking into account Nusselt number as a function of Reynolds and Prandtl number. Most experimenters spend their effort to control turbulence level, set it to different values, or keep it unchanged during the tests, as it’s not easy to predict how its initial level may change final results. The aim of this work is to add some comprehension on how different turbulence incoming levels may affect heat transfer measurements, and when it’s possible or not to neglect such effects. Experimental setup features different duct geometries, and thermocromic liquid crystals coupled with hot-wire anemometers are used as main measurement techniques. Tests were performed for Reynolds number from 10000 to 50000 and turbulence level from 3% to 12%. Several turbulence manipulators were adopted, including aluminum foams and multi-perforated plates, and results show some interesting dependences of heat transfer from both turbulence level and grid features.

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Coriolis Effect on Heat Transfer Experiment using Hot-Wire Technique on Centrifuge

Materials Processing in High Gravity ◽

10.1007/978-1-4615-2520-2_17 ◽

1994 ◽

pp. 171-179 ◽

Cited By ~ 1

Author(s):

Taketoshi Hibiya ◽

Shin Nakamura ◽

Kyung-Woo Yi ◽

Koichi Kakimoto

Keyword(s):

Heat Transfer ◽

Coriolis Effect ◽

Hot Wire ◽

Transfer Experiment

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Heat Transfer from Thin Wires to Superfluid Helium under Reduced Gravity

Advances in Cryogenic Engineering ◽

10.1007/978-1-4613-2213-9_57 ◽

1986 ◽

pp. 499-504 ◽

Cited By ~ 12

Author(s):

Th. Gradt ◽

Z. Szücs ◽

H.-D. Denner ◽

G. Klipping

Keyword(s):

Heat Transfer ◽

Superfluid Helium ◽

Reduced Gravity ◽

Thin Wires

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HOT WIRE METHOD FOR THE THERMAL CHARACTERIZATION OF MATERIALS: INVERSE PROBLEM APPLICATION

Revista de Engenharia Térmica ◽

10.5380/ret.v2i2.3470 ◽

2003 ◽

Vol 2 (2) ◽

Cited By ~ 2

Author(s):

S. André ◽

B. Rémy ◽

F. R. Pereira ◽

N. Cella ◽

A. J. Silva Neto

Keyword(s):

Heat Transfer ◽

Thermal Characterization ◽

Hot Wire ◽

Confidence Bounds ◽

Linear Temperature ◽

Direct Model ◽

Electrical Analogy ◽

Wire Method ◽

Characterization Of Materials ◽

Set Up

An experimental set-up of the hot wire method is presented. The present design allows the measurement of the temperatures at two different points on the heating wire with an acquisition system that performs measurements at a frequency of 1kHz with a 12 bit numerical converter. An analytical solution for the direct model for the time dependent problem of heat transfer is employed. It is based on the quadrupole method which basically consists in a transfer matrix approach which is possible through the use of Laplace transforms. It extends the electrical analogy of heat transfer problems using the notion of impedance, and allows to take into account the thermal behavior of the wire, as well as contact resistance and heat loss effects in a very simple straightforward way. In the identification process carried on the temperature experimental data relies on a sampling of the data that is logarithmically spaced in time. The initial guesses for the thermal conductivity values are obtained applying the well known and ideal model of the linear temperature evolution versus the logarithm of the time. These values are used to start up the algorithms that are applied in the minimization of the cost functional of the squared residues between measured and calculated temperatures. The precision of the estimates is assessed with the calculated confidence bounds obtained by the variance-covariance matrix at the converged solution.

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Hot-Wire Measurements in Non-Calibrated Conditions

10.1115/gt2021-59259 ◽

2021 ◽

Author(s):

Yuexin Wang ◽

Tao Guo ◽

Huiren Zhu

Keyword(s):

Heat Transfer ◽

Forced Convection ◽

Convection Heat Transfer ◽

Calibration Method ◽

Heat Radiation ◽

Average Error ◽

Convection Heat ◽

Hot Wire ◽

Forced Convection Heat Transfer ◽

Temperature And Pressure

Abstract The hot-wire anemometer is a widely used instrumentation to determine flow velocity and to investigate flow quality. The main objective of this paper is to expand the application range of the hot wire by improving the measurement accuracy under non-calibrated temperature and pressure. According to the four kinds of heat transfer derivations, a new calibration method was carried out. Considering natural convection, heat radiation and heat conduction, and forced convection heat transfer, it can be found that the forced convection heat transfer plays a dominant role, and the main factor causing the change is the temperature. Forced convection heat transfer also changes with pressure, which affects heat transfer by affecting kinematic viscosity. Based on this, a new calibration method and formula of velocity were put forward, which can be used over a range of temperature and pressure, considering the changes of physical property of the calibration scheme were verified by numerical simulation. The numerical calculated results were compared, the average error was 0.69%, the maximum error was 2.9%. The results show that the calibration method has high accuracy in a certain range. This paper provides a new solution for the calibration of hot-wire anemometer, and expands the adaptability of hot-wire anemometer in the measurement of severe external conditions.

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A HEAT TRANSFER MODEL STUDY OF THE HOT WIRE INITIATOR

10.21236/ad0602664 ◽

1964 ◽

Cited By ~ 1

Author(s):

Jr Massey ◽

J. M.

Keyword(s):

Heat Transfer ◽

Heat Transfer Model ◽

Transfer Model ◽

Hot Wire ◽

Model Study

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The Uncertainties of Continuum-Based CFD Solvers to Perform Microscale Hot-Wire Anemometer Simulations in Flow Fields Close to Transitional Regime

Volume 2: Micro/Nano-Thermal Manufacturing and Materials Processing; Boiling, Quenching and Condensation Heat Transfer on Engineered Surfaces; Computational Methods in Micro/Nanoscale Transport; Heat and Mass Transfer in Small Scale; Micro/Miniature Multi-Phase Devices; Biomedical Applications of Micro/Nanoscale Transport; Measurement Techniques and Thermophysical Properties in Micro/Nanoscale; Posters ◽

10.1115/mnhmt2016-6697 ◽

2016 ◽

Author(s):

Masoud Darbandi ◽

Mohammad Reza Ghorbani ◽

Hamed Darbandi

Keyword(s):

Heat Transfer ◽

Numerical Solutions ◽

Stokes Equations ◽

Slip Flow ◽

Convection Heat Transfer ◽

Flow Fields ◽

Transitional Flow ◽

Hot Wire ◽

Fixed Temperature ◽

Cfd Method

In this study, we simulate the flow and heat transfer during hot-wire anemometry and investigate its thermal behavior and physics using the Computational Fluid Dynamics (CFD) tool. In this regard, we use the finite-volume method and solve the compressible Navier-Stokes equations numerically in slightly non-continuum flow fields. We do not use any slip flow model to include the transitional flow physics in our simulations. Using the CFD method, we simulate the flow over hot–wire and evaluate the uncertainty of CFD in thermal simulation of hot-wire in low transitional flow regimes. The domain sizes and the mesh distributions are carefully chosen to avoid boundary condition error appearances. Following the past researches, we do not take into account the conduction heat transfer passing through hot-wire mounting arms in our simulations. Imposing a fixed temperature condition at the face of hot-wire, we simulate the flow over and the heat transfer from hot-wire and calculate the convection heat transfer coefficient and the local Nusselt number values. To be sure of the accuracy of our CFD code, we simulate a number of similar test cases and compare our numerical solutions with the available numerical solutions and/or experimental data.

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Hot-Wire Measurements of Turbulence Correlations in a Triangular Duct

Journal of Applied Mechanics ◽

10.1115/1.3640643 ◽

1962 ◽

Vol 29 (4) ◽

pp. 609-614 ◽

Cited By ~ 11

Author(s):

C. J. Cremers ◽

E. R. G. Eckert

Keyword(s):

Heat Transfer ◽

Laminar Flow ◽

Cross Section ◽

Circular Tube ◽

Turbulent Transport ◽

Circular Cross Section ◽

Hot Wire ◽

Round Tube ◽

Flow Through ◽

Hot Wires

Previous studies by flow visualization have indicated that the flow through a duct of triangular cross section is in its characteristics quite different from flow through a duct with circular cross section. They revealed among others that purely laminar flow exists in the corners of the duct even though the bulk of the fluid moves in turbulent motion. Heat-transfer measurements in such a duct appear to indicate that the turbulent transport in the direction of the height of the duct is considerably smaller than expected from circular tube measurements. The present paper reports the measurements of turbulent correlations for turbulent flow through such a duct. These measurements have been made with hot wires of very small dimensions. They again reveal the existence of a laminar corner region. In the bulk of the fluid, the differences of the correlations to those in a round tube turned out to be smaller than originally suspected.

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