- Author
- Filipczak, R. | Lyon, R. E.
- Title
- Heat Flux Measurements in the Ohio State University Rate of Heat Release Apparatus. Technical Note.
- Coporate
- Federal Aviation Administration, Atlantic City International Airport, NJ
- Sponsor
- Department of Transportation, Washington, DC
- Report
- DOT/FAA/AR-TN00/38, August 2000, 15 p.
- Distribution
- AVAILABLE FROM National Technical Information Service (NTIS), Technology Administration, U.S. Department of Commerce, Springfield, VA 22161. Telephone: 1-800-553-6847 or 703-605-6000; Fax: 703-605-6900; Rush Service (Telephone Orders Only) 800-553-6847; Website: http://www.ntis.gov
- Keywords
- heat flux | heat release rate | heat transfer | pilot flame | calorimeters | convective heat transfer
- Abstract
- The Ohio State University (OSU) fire calorimeter is the mandated test apparatus for aircraft interior materials as described in Federal Aviation Regulation (FAR) 25.853. Initial round-robin testing by the Federal Aviation Administration (FAA) and three members of the Aerospace Industries Association (AIA) of five types of composite panels and three thermoplastic materials showed a 25.2% Relative Standard Deviation (RSD) for the 2 minute integrated heat release when tests were conducted in accordance with the American Society of Testing (ASTM) E 906, "Heat and Visible Smoke Release Rates for Materials and Products". Although other equipment modifications were made to the OSU, standardization of the various test apparatus with a single heat flux transducer was thought to be the most important factor in reducing the interlaboratory disparity to the more manageable 14.1% RSD that was seen for the second round robin. A third round robin involving 15 laboratories in the United States, Europe, and Canada and 13 aircraft materials demonstrated 7.7% RSD for the 2 minute integrated heat release and 7.8% RSD for the peak heat release value. Variation in the specified 35 kW/m2 incident heat flux at the sample surface remains a potential source of error and significant effort has been expended in addressing this problem. This paper addresses the measurement of incident heat flux in the OSU apparatus at both the overall sample surface and at the spot of pilot flame impingement. The slug calorimeter represents a potential corroborating method for Gardon Heat Flux Sensor measurements of cold-wall heat flux in applications where measurement of constant, uniform heat flux is required. Unlike the Gardon Heat Flux Sensor, the slug calorimeter is a primary standard. This means calibration is not required, since the temperature change, weight, and surface area of the slug are measured and used to calculate the heat flux for a mass of known heat capacity. The weight of the copper slug is measured on a calibrated balance, accurate to the milligram. The heat capacity of copper at 18 deg C (65 deg F) is 384.9 J/(Kg-K). The surface area of the slug is measured using a ruler. The slug temperature is recorded using a data acquisition system and a thermocouple. The rate of temperature change of the copper slug is then defined as the change of energy applied to the slug. The only variable remaining for the system is the absorptivity of the blackened coating that is applied. If all incident radiation is assumed to be completely absorbed,. The actual absorptivity of 3M ECP-2200 Solar Absorber Coating has been determined by reflectance Fourier transform infrared spectroscopy (FTIR). Since energy can only be lost through conduction, convection, or reradiation, the resulting energy balance is compared to the Gardon gauge test standard, which was used to calibrate the radiant source immediately prior to insertion of the slug.