Problems Encountered in Fluctuating Flame Temperature Measurements by Thermocouple

Journal Article · Wed Dec 03 23:00:00 EST 2008 · Sensors

DOI:https://doi.org/10.3390/s8127882· OSTI ID:1628567

Yilmaz, Nadir ^[1]; Gill, Walt ^[2]; Donaldson, A. Burl ^[2]; Lucero, Ralph ^[3]

---

1. New Mexico Inst. of Mining and Technology, Socorro, NM (United States). Dept. of Mechanical Engineering; DOE/OSTI
2. Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
3. New Mexico State Univ., Las Cruces, NM (United States). Dept. of Mechanical Engineering

Some thermocouple experiments were carried out in order to obtain sensitivity of thermocouple readings to fluctuations in flames and to determine if the average thermocouple reading was representative of the local volume temperature for fluctuating flames. The thermocouples considered were an exposed junction thermocouple and a fully sheathed thermocouple with comparable time constants. Either the voltage signal or indicated temperature for each test was recorded at sampling rates between 300-4,096 Hz. The trace was then plotted with respect to time or sample number so that time variation in voltage or temperature could be visualized and the average indicated temperature could be determined. For experiments where high sampling rates were used, the signal was analyzed using Fast Fourier Transforms (FFT) to determine the frequencies present in the thermocouple signal. This provided a basic observable as to whether or not the probe was able to follow flame oscillations. To enhance oscillations, for some experiments, the flame was forced. An analysis based on thermocouple time constant, coupled with the transfer function for a sinusoidal input was tested against the experimental results.

• Research Organization: Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Basic Energy Sciences (BES). Materials Sciences & Engineering Division
• Grant/Contract Number: NA0003525
• OSTI ID: 1628567
• Journal Information: Sensors, Journal Name: Sensors Journal Issue: 12 Vol. 8; ISSN SENSC9; ISSN 1424-8220
• Publisher: MDPI AG
• Country of Publication: United States
• Language: English

Related Subjects

Thermocouple transfer function
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
42 ENGINEERING
47 OTHER INSTRUMENTATION
Chemistry
Diffusion flames
Engineering
Flame thermocouple measurement
Fluctuating flames
Instruments & Instrumentation