1、Designation: E3057 16Standard Test Method forMeasuring Heat Flux Using Directional Flame Thermometerswith Advanced Data Analysis Techniques1This standard is issued under the fixed designation E3057; the number immediately following the designation indicates the year oforiginal adoption or, in the ca
2、se of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.INTRODUCTIONThis test method describes a technique for measuring the net heat flux to one or both surf
3、aces ofa sensor called a Directional Flame Thermometer. The sensor covered by this standard usesmeasurements of the temperature response of two metal plates along with a thermal model of thesensor to determine the net heat flux. These measurements can be used to estimate the total heat flux(aka ther
4、mal 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 fluxoriginated because commercially available, water-cooled heat flux gauges (for example, Gardon andSchmidt-Boelter gauges) did not work
5、 as desired in large fire tests. Because the Gardon andSchmidt-Boelter (S-B) gauges are water cooled, condensation and soot deposition can occur duringfire testing or in furnaces. Both foul the sensing surface which in turn changes the sensitivity(calibration) of the gauge. This results in an error
6、during data reduction. Therefore, a different type ofsensor was needed; one such sensor is a DFT. DFTs are not cooled so condensation and soot depositionare minimized or eliminated.Additionally, a body of work has shown that for both Gardon and Schmidt-Boelter gauges thesensitivity coefficients dete
7、rmined 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 forcalibration Test Method E511-07; Keltner and Wildin, 1975 (1, 2); Borell, G. J., and Diller, T. E.,1987 (3); Gifford, A., et
8、 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.T., and Brown,A. L., 2011 (11).2As a result, one can incur significant bias errors when reducing datain tests where t
9、here may be a non-negligible convective component because the only sensitivitycoefficient available is for a radiation calibration. It was desired to reduce/eliminate these potentialsource of error by designing a gauge that does not depend on a radiation only calibration. DFTs havethis characteristi
10、c.A sensor, also called a Directional Flame Thermometer, was developed to help estimate flamethickness 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,DF
11、Ts were quasi-equilibrium sensors that used a thin metal plate with a single thermocouple attachedand backed by multiple radiation shields. To make a sensor suitable for continuous transient heat fluxmeasurements, this basic design was modified to use two instrumented plates, with a layer ofinsulati
12、on in between.For the Directional Flame Thermometers described in this standard, the net heat flux is calculatedusing transient temperature measurements of the two plates and temperature dependent materialproperties for the plates and the insulation. Three methods are described in this standard to c
13、alculatethe net heat flux. The most accurate method for calculating the net heat flux is believed to be the1-dimensional, nonlinear inverse heat conduction analysis, which uses the IHCP1D code. This is basedon uncertainty analyses and comparisons with measurements made with Schmidt-Boelter and Gardo
14、ngauges, which have NIST traceable calibrations. The second method uses a transient energy balanceson the DFT. As will be shown below, the energy balance method compares very well with the inversemethod, again based on uncertainty analyses. The third method uses sets of linearized, convolutiondigita
15、l filters based on IHCP1D. These allow a near real-time calculation of the net heat flux Keltner,N. R., 2007 (16); Keltner, N. R., et al., 2010 (17). See Section 1 for more detailed information on eachCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959.
16、 United States1analysis technique. Additional information is given in the Annexes and Appendices.Various DFT designs have been used in a variety of applications including very large pool fires,LNG spill fires, marine fire safety testing, automobile fires, to study rocket launch accident fires, andin
17、 research of forest and wild-land fires. Appendix X1 provides a comprehensive list of applicationswhere DFTs have been successfully used.Advantages of DFTs are their relatively low cost, ease of construction, they require no calibration(see later), and require no cooling. They are robust and can sur
18、vive intense fire environments withoutfailure. Disadvantages include most are large compared with Gardon and S-B heat flux gauges andbecause they are not calibrated, one cannot reference the measurements to a NIST standard. Becauseno calibration is required, one must quantify the uncertainties prese
19、nt in the temperature measure-ments and the data reduction methods used to calculate the heat flux. Also, DFTs measure net heatflux; for a direct comparison with Gardon and S-B gauges, which are calibrated to incident (or “coldwall”) flux, one must use a thermal model to estimate the incident flux.T
20、he best applications for DFTs are where Gardon and S-B gauges cannot be used (for example, dueto high temperatures, lack of cooling, soot deposition, fouling, and so forth), or when long life andoverall costs are a consideration. Gardon and Schmidt-Boelter gauges are recommended in non-sootyenvironm
21、ents, when it is possible to mount the gauges and cooling lines, and in predominantlyradiative environments with a small convective contribution.1. Scope1.1 This test method describes the continuous measurementof the hemispherical heat flux to one or both surfaces of anuncooled sensor called a “Dire
22、ctional Flame Thermometer”(DFT).1.2 DFTs consist of two heavily oxidized, Inconel 600plates with mineral insulated, metal-sheathed (MIMS) thermo-couples (TCs, type K) attached to the unexposed faces and alayer of ceramic fiber insulation placed between the plates.1.3 Post-test calculations of the ne
23、t heat flux can be madeusing several methods The most accurate method uses aninverse heat conduction code. Nonlinear inverse heat conduc-tion analysis uses a thermal model of the DFT with temperaturedependent thermal properties along with the two plate tempera-ture measurement histories. The code pr
24、ovides transient heatflux on both exposed faces, temperature histories within theDFT as well as statistical information on the quality of theanalysis.1.4 A second method uses a transient energy balance on theDFT sensing surface and insulation, which uses the sametemperature measurements as in the in
25、verse calculations toestimate the net heat flux.1.5 A third method uses Inverse Filter Functions (IFFs) toprovide a near real time estimate of the net flux. The heat fluxhistory for the “front face” (either surface exposed to the heatsource) of a DFT can be calculated in real-time using aconvolution
26、 type of digital filter algorithm.1.6 Although developed for use in fires and fire safetytesting, this measurement method is quite broad in potentialfields of application because of the size of the DFTs and theirconstruction. It has been used to measure heat flux levels above300 kW/m2in high tempera
27、ture environments, up to about1250C, which is the generally accepted upper limit of Type Kor N thermocouples.1.7 The transient response of the DFTs is limited by theresponse of the MIMS TCs. The larger the thermocouple theslower the transient response. Response times of approxi-mately 1 to 2 s are t
28、ypical for 1.6 mm diameter MIMS TCsattached to 1.6 mm thick plates. The response time can beimproved by using a differential compensator.1.8 The values stated in SI units are used in this standard.The values stated in parentheses are provided for informationonly.1.9 This standard does not purport to
29、 address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:3C177 Test
30、 Method for Steady-State Heat Flux Measure-ments and Thermal Transmission Properties by Means ofthe Guarded-Hot-Plate ApparatusE119 Test Methods for Fire Tests of Building Constructionand MaterialsE176 Terminology of Fire StandardsE457 Test Method for Measuring Heat-Transfer Rate Usinga Thermal Capa
31、citance (Slug) Calorimeter1This test method was jointly developed by ASTM Committee E21 on Space Simulation and Applications of Space Technology and is the direct responsibility ofSubcommittee E21.08 on Thermal Protection.Current edition approved April 1, 2016. Published May 2016. DOI: 10.1520/E3057
32、-16,2The boldface numbers in parentheses refer to the list of references at the end of this standard.3For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards D
33、ocument Summary page onthe ASTM website.E3057 162E459 Test Method for Measuring Heat Transfer Rate Usinga Thin-Skin CalorimeterE511 Test Method for Measuring Heat Flux Using a Copper-Constantan Circular Foil, Heat-Flux TransducerE1529 Test Methods for Determining Effects of Large Hy-drocarbon Pool F
34、ires on Structural Members and Assem-bliesE2683 Test Method for Measuring Heat Flux Using Flush-Mounted Insert Temperature-Gradient Gages2.2 Other Standards:ISO 834-11:2014 Fire Resistance TestsElements of Build-ing ConstructionPart 11: Specific Requirements for theAssessment of Fire Protection to S
35、tructural Steel Ele-ments4MNL12-4th Manual on the Use of Thermocouples in Tem-perature Measurement, Fourth Edition, 1993, Sponsoredby ASTM Committee E20 on Temperature Measurement3. Terminology3.1 DefinitionsRefer to Terminology in ASTM StandardE176 for definitions of some terms used in these test m
36、ethods.3.2 Definitions of Terms Specific to This Standard:3.2.1 incident radiative heat flux (irradiance; qinc,r),nradiative heat flux impinging on the surface of the DFT orthe unit under test.3.2.2 net heat flux, nstorage in the DFT front plate +transmission (in other words, loss) to insulation lay
37、er. It isequal to the absorbed radiative heat flux + convective heatflux re-radiation from the exposed surface.3.2.3 total absorbed heat flux, nabsorbed radiative heatflux + convective flux.3.2.4 total cold wall heat flux, nthe heat flux that would betransferred by means of convection and radiation
38、to an objectwhose temperature is 21C (70F).3.2.5 total heat flux (thermal exposure), nincident radia-tive heat flux + convective heat flux.4. Summary of Test Method4.1 This test method provides techniques for measurementof the net heat flux to a surface. Because Directional FlameThermometers are un-
39、cooled devices, they are minimallyaffected by soot deposition or condensation. Calibration factorsor sensitivity coefficients are not required because alternatemethods of data reduction are used. DFTs are simple tofabricate and use, but are more complicated when reducing thedata. Gardon and Schmidt-
40、Boelter gauges have relativelylinear outputs with heat flux and only require a single sensi-tivity coefficient (for example, xx mv/unit of flux) to convertthe output to an incident heat flux. DFTs have two thermo-couple outputs as a function of time. Those outputs along withtemperature dependent the
41、rmal properties and advanced analy-sis techniques are used with a thermal model to calculate thenet heat flux. The net heat flux (with an energy balance) can beused to estimate the total cold wall heat flux, which is same asthe measurement made by Gardon or S-B gauges Janssens,2007 (18).5. Significa
42、nce and Use5.1 Need for Heat Flux Measurements:5.1.1 Independent measurements of temperature and heatflux support the development and validation of engineeringmodels of fires and other high environments, such as furnaces.For tests of fire protection materials and structural assemblies,temperature an
43、d heat flux are necessary to fully specify theboundary conditions, also known as the thermal exposure.Temperature measurements alone cannot provide a completeset of boundary conditions.5.1.2 Temperature is a scalar variable and a primary vari-able. Heat Flux is a vector quantity and it is a derived
44、variable.As a result, they should be measured separately just as currentand voltage are in electrical systems. For steady-state orquasi-steady state conditions, analysis basically uses a thermalanalog of Ohms Law. The thermal circuit uses the temperaturedifference instead of voltage drop, the heat f
45、lux in place of thecurrent and thermal resistance in place of electrical resistance.As with electrical systems, the thermal performance is not fullyspecified without knowing at least two of these three param-eters (temperature drop, heat flux, or thermal resistance). Fordynamic thermal experiments l
46、ike fires or fire safety tests, theelectrical capacitance is replaced by the volumetric heatcapacity.5.1.3 The net heat flux, which is measured by a DFT, islikely different than the heat flux into the test item of interestbecause of different surface temperatures. An alternative mea-surement is the
47、total cold wall heat flux which is measured bywater-cooled Gardon or S-B gauges. The incident radiative fluxcan be estimated from either measurement by use of an energybalance Keltner, 2007 and 2008 (16, 17). The convective fluxcan be estimated from gas temperatures and the convectiveheat transfer c
48、oefficient, h Janssens, 2007 (18). Assuming thesensor is physically close to the test item of interest; one canuse the incident radiative and convective fluxes from the sensoras boundary conditions into the test item of interest.5.1.4 In standardized fire resistance tests such as TestMethods E119 an
49、d E1529, or ISO 834 or IMO A754, thefurnace temperature is controlled to a standard time-temperature curve. In all but Test Methods E1529, implicitassumptions have been made that the thermal exposure can bedescribed solely by the measured furnace temperature historyand that it will be repeatable from time to time and place toplace. However, these tests provide very different thermalexposures due to the use of temperature sensors with verydifferent designs for furnace control.As a result, these differentthermal exposure histories produce different fire rat
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