ASTM E3057-19
(Test Method)Standard Test Method for Measuring Heat Flux Using Directional Flame Thermometers with Advanced Data Analysis Techniques
Standard Test Method for Measuring Heat Flux Using Directional Flame Thermometers with Advanced Data Analysis Techniques
SIGNIFICANCE AND USE
5.1 Need for Heat Flux Measurements:
5.1.1 Independent measurements of temperature and heat flux support the development and validation of engineering models of fires and other high environments, such as furnaces. For tests of fire protection materials and structural assemblies, temperature and heat flux are necessary to fully specify the boundary conditions, also known as the thermal exposure. Temperature measurements alone cannot provide a complete set of boundary conditions.
5.1.2 Temperature is a scalar variable and a primary variable. Heat Flux is a vector quantity, and it is a derived variable. As a result, they should be measured separately just as current and voltage are in electrical systems. For steady-state or quasi-steady state conditions, analysis basically uses a thermal analog of Ohm's Law. The thermal circuit uses the temperature difference instead of voltage drop, the heat flux in place of the current and thermal resistance in place of electrical resistance. As with electrical systems, the thermal performance is not fully specified without knowing at least two of these three parameters (temperature drop, heat flux, or thermal resistance). For dynamic thermal experiments like fires or fire safety tests, the electrical capacitance is replaced by the volumetric heat capacity.
5.1.3 The net heat flux, which is measured by a DFT, is likely different than the heat flux into the test item of interest because of different surface temperatures. An alternative measurement is the total cold wall heat flux which is measured by water-cooled Gardon or S-B gauges. The incident radiative flux can be estimated from either measurement by use of an energy balance [Keltner, 2007 and 2008 (16, 17)]. The convective flux can be estimated from gas temperatures and the convective heat transfer coefficient, h [Janssens, 2007 (18)]. Assuming the sensor is physically close to the test item of interest; one can use the incident radiative and convective fluxes from the...
SCOPE
1.1 This test method describes the continuous measurement of the hemispherical heat flux to one or both surfaces of an uncooled sensor called a “Directional Flame Thermometer” (DFT).
1.2 DFTs consist of two heavily oxidized, Inconel 600 plates with mineral insulated, metal-sheathed (MIMS) thermocouples (TCs, type K) attached to the unexposed faces and a layer of ceramic fiber insulation placed between the plates.
1.3 Post-test calculations of the net heat flux can be made using several methods. The most accurate method uses an inverse heat conduction code. Nonlinear inverse heat conduction analysis uses a thermal model of the DFT with temperature dependent thermal properties along with the two plate temperature measurement histories. The code provides transient heat flux on both exposed faces, temperature histories within the DFT as well as statistical information on the quality of the analysis.
1.4 A second method uses a transient energy balance on the DFT sensing surface and insulation, which uses the same temperature measurements as in the inverse calculations to estimate the net heat flux.
1.5 A third method uses Inverse Filter Functions (IFFs) to provide a near real time estimate of the net flux. The heat flux history for the “front face” (either surface exposed to the heat source) of a DFT can be calculated in real-time using a convolution type of digital filter algorithm.
1.6 Although developed for use in fires and fire safety testing, this measurement method is quite broad in potential fields of application because of the size of the DFTs and their construction. It has been used to measure heat flux levels above 300 kW/m2 in high temperature environments, up to about 1250 °C, which is the generally accepted upper limit of Type K or N thermocouples.
1.7 The transient response of the DFTs is limited by the response of the MIMS TCs. The larger the thermocouple the slower the transient response. Res...
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This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: E3057 − 19
Standard Test Method for
Measuring Heat Flux Using Directional Flame Thermometers
1
with Advanced Data Analysis Techniques
This standard is issued under the fixed designation E3057; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
INTRODUCTION
This test method describes a technique for measuring the net heat flux to one or both surfaces of
a sensor called a Directional Flame Thermometer. The sensor covered by this standard uses
measurements of the temperature response of two metal plates along with a thermal model of the
sensor to determine the net heat flux. These measurements can be used to estimate the total heat flux
(also known as thermal exposure) and bi-directional heat fluxes for use in CFD thermal models.
The development of Directional Flame Thermometers (DFTs) as a device for measuring heat flux
originated because commercially available, water-cooled heat flux gauges (for example, Gardon and
Schmidt-Boelter gauges) did not work as desired in large fire tests. Because the Gardon and
Schmidt-Boelter (S-B) gauges are water cooled, condensation and soot deposition can occur during
fire testing or in furnaces. Both foul the sensing surface which in turn changes the sensitivity
(calibration) of the gauge. This results in an error during data reduction. Therefore, a different type of
sensorwasneeded;onesuchsensorisaDFT.DFTsarenotcooledsocondensationandsootdeposition
are minimized or eliminated.
Additionally, a body of work has shown that for both Gardon and Schmidt-Boelter gauges the
sensitivity coefficients determined through the calibration process, which uses a radiative heat source,
are not the same as the sensitivity coefficients determined if a purely convective source is used for
calibration [Test Method E511-07; Keltner and Wildin, 1975 (1, 2); Borell, G. J., and Diller, T. E.,
1987 (3); Gifford,A., et al., 2010 (4); Gritzo, L.A., et al., 1995 (5); Young, M. F., 1984 (6); Sobolik,
et al., 1987 (7); Kuo and Kulkarni, 1991 (8); Keltner, 1995 (9); Gifford, et al., 2010 (10); Nakos, J.
2
T., and Brown,A. L., 2011 (11)]. As a result, one can incur significant bias errors when reducing data
in tests where there may be a non-negligible convective component because the only sensitivity
coefficient available is for a radiation calibration. It was desired to reduce/eliminate these potential
sources of error by designing a gauge that does not depend on a radiation only calibration. DFTs have
this characteristic.
A sensor, also called a Directional Flame Thermometer, was developed to help estimate flame
thickness in pool fire tests of hazardous material shipping containers [Burgess, M. H., 1986 (12); Fry,
C. J., 1989 (13); Burgess, M. H., et al., 1990 (14); and Fry, C. J., 1992 (15)].As originally designed,
DFTs were quasi-equilibrium sensors that used a thin metal plate with a single thermocouple attached
and backed by multiple radiation shields. To make a sensor suitable for continuous transient heat flux
measurements, this basic design was modified to use two instrumented plates, with a layer of
insulation in between.
For the Directional Flame Thermometers described in this standard, the net heat flux is calculated
using transient temperature measurements of the two plates and temperature dependent material
properties for the plates and the insulation. Three methods are described in this standard to calculate
the net heat flux. The most accurate method for calculating the net heat flux is believed to be the
1-dimensional,nonlinearinverseheatconductionanalysis,whichusestheIHCP1Dcode.Thisisbased
on uncertainty analyses and comparisons with measurements made with Schmidt-Boelter and Gardon
gauges,whichhaveNISTtraceablecalibrations.Thesecondmethodusestransientenergybalanceson
the DFT. As will be shown below, the energy balance method compares very well with the inverse
method, again based on uncertainty analyses. The third method uses sets of linearized, convolution
digital filters based on IHCP1D.These allow a near real-time calculation of the net heat flux [Keltner,
N.R.,2007 (16);Keltner,N.R.,etal.,2010 (17)].SeeSection1formoredetailedinformationoneach
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
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E3057 − 19
analysis technique. Additional information is given in the Annexes and Appendices.
Various DFT designs h
...
This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: E3057 − 16 E3057 − 19
Standard Test Method for
Measuring Heat Flux Using Directional Flame Thermometers
1
with Advanced Data Analysis Techniques
This standard is issued under the fixed designation E3057; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
INTRODUCTION
This test method describes a technique for measuring the net heat flux to one or both surfaces of
a sensor called a Directional Flame Thermometer. The sensor covered by this standard uses
measurements of the temperature response of two metal plates along with a thermal model of the
sensor to determine the net heat flux. These measurements can be used to estimate the total heat flux
(aka (also known as thermal exposure) and bi-directional heat fluxes for use in CFD thermal models.
The development of Directional Flame Thermometers (DFTs) as a device for measuring heat flux
originated because commercially available, water-cooled heat flux gauges (for example, Gardon and
Schmidt-Boelter gauges) did not work as desired in large fire tests. Because the Gardon and
Schmidt-Boelter (S-B) gauges are water cooled, condensation and soot deposition can occur during
fire testing or in furnaces. Both foul the sensing surface which in turn changes the sensitivity
(calibration) of the gauge. This results in an error during data reduction. Therefore, a different type of
sensor was needed; one such sensor is a DFT. DFTs are not cooled so condensation and soot deposition
are minimized or eliminated.
Additionally, a body of work has shown that for both Gardon and Schmidt-Boelter gauges the
sensitivity coefficients determined through the calibration process, which uses a radiative heat source,
are not the same as the sensitivity coefficients determined if a purely convective source is used for
calibration [Test Method E511-07; Keltner and Wildin, 1975 (1, 2); Borell, G. J., and Diller, T. E.,
1987 (3); Gifford, A., et al., 2010 (4); Gritzo, L. A., et al., 1995 (5); Young, M. F., 1984 (6); Sobolik,
et al., 1987 (7); Kuo and Kulkarni, 1991 (8); Keltner, 1995 (9); Gifford, et al., 2010 (10); Nakos, J.
2
T., and Brown, A. L., 2011 (11)]. As a result, one can incur significant bias errors when reducing data
in tests where there may be a non-negligible convective component because the only sensitivity
coefficient available is for a radiation calibration. It was desired to reduce/eliminate these potential
sourcesources of error by designing a gauge that does not depend on a radiation only calibration. DFTs
have this characteristic.
A sensor, also called a Directional Flame Thermometer, was developed to help estimate flame
thickness in pool fire tests of hazardous material shipping containers [Burgess, M. H., 1986 (12); Fry,
C. J., 1989 (13); Burgess, M. H., et al., 1990 (14); and Fry, C. J., 1992 (15)]. As originally designed,
DFTs were quasi-equilibrium sensors that used a thin metal plate with a single thermocouple attached
and backed by multiple radiation shields. To make a sensor suitable for continuous transient heat flux
measurements, this basic design was modified to use two instrumented plates, with a layer of
insulation in between.
For the Directional Flame Thermometers described in this standard, the net heat flux is calculated
using transient temperature measurements of the two plates and temperature dependent material
properties for the plates and the insulation. Three methods are described in this standard to calculate
the net heat flux. The most accurate method for calculating the net heat flux is believed to be the
1-dimensional, nonlinear inverse heat conduction analysis, which uses the IHCP1D code. This is based
1
This test method was jointly developed by ASTM Committee E21 on Space Simulation and Applications of Space Technology and is the direct responsibility of
Subcommittee E21.08 on Thermal Protection.
Current edition approved April 1, 2016June 1, 2019. Published May 2016July 2019. Originally approved in 2016. Last previous edition approved in 2016 as E3057 – 16.
DOI: 10.1520/E3057-16,10.1520/E3057-19.
2
The boldface numbers in parentheses refer to the list of references at the end of this standard.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
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