Novel Approaches to Improve the Sensitivity of Aerosol Phosphor Thermometry Measurements
Abstract
Temperature is a critically important parameter in combustion systems. Due to its significance, a great deal of effort has been focused on developing methods to measure gas and surface temperatures in combustion systems. Even so, accurate spatially and temporally resolved measurements of temperature over the entire range of interest remain elusive. The proposed work will improve the accuracy and extend the range of gas temperature measurements using aerosol phosphor thermometry (APT) by studying novel methods to improve the temperature sensitivity of the technique. APT utilizes seeding of micron-sized phosphor particles into gases to enable simultaneous spatially-resolved measurements of velocity and temperature. To date, accurate single-shot measurements of gas temperature using APT have been limited to temperatures < 800 K. This is the result of two factors that occur with increasing temperature: decreasing fractional sensitivity and reduction in signal-to-noise ratio. The diagnostic precision is inversely proportional to the product of fractional sensitivity and the signal-to-noise ratio, such that the decrease of both with increasing temperature results in worse measurement accuracy. Recent work by the PI s group has identified phosphors with fast emission and high signal-to-noise ratios at higher temperatures than previously achieved. However, the fractional sensitivity of these phosphors remains poor and decreases with temperature resulting in large single-shot temperature uncertainties using current methods. The proposed work will study two novel methods for significantly increasing the fractional sensitivity and accuracy of APT at temperatures > 800 K. The first of the two methods utilizes the ratio of fluorescence emission from two co-doped ions to obtain increased sensitivity. The second proposed method, utilizes the temperature dependent emission from a singly-doped phosphor relative to the particle Mie scattering signal. The primary objectives for the proposed work are: 1. Determine the feasibility of the co-doped ratio method to be used to obtain improved fractional sensitivity for APT., 2. Determine the feasibility of the Mie ratio method to provide improved accuracy for APT measurements. 3. Demonstrate improvements using the two methods in a heated air jet. The work will result in improved measurements of gas temperature in combustion systems of interest to the Army and will provide the foundation for future efforts focused on further expanding the temperature measurement range and accuracy of aerosol phosphor thermometry.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Sep 11, 2018
- Source ID
- W911NF1810147
Entities
People
- David A Rothamer
Organizations
- Army Contracting Command
- United States Army
- University of Wisconsin–Madison