Study of acetone vapor phosphorescence at varying temperatures for molecular tagging thermometry

Studying the gas flows at rarefied conditions is imperative in the fields of gas sensing, micro gas heat exchangers, reentry of space vehicles etc. The last couple of decades has witnessed a considerable progress in this domain on theoretical and numerical fronts. However, there is a clear lack of extensive experimental data, and the main underlying reason is the challenging nature of experimentation at rarefied conditions. In this regard, molecular tagging technique has the potential to become a significant experimental technique in the field of rarefied gas flows. In principle, molecular tagging approaches can be used for local measurements of velocity and temperature. The former is generally referred as molecular tagging velocimetry (MTV). The latter is the focus of this study, and is referred as molecular tagging thermometry (MTT). Due to the employment of molecules as tracers emitting light once excited by a light source, there is a minimal intrusion of these molecules with the overall flow behavior. Acetone and biacetyl are generally employed as tracers by researchers for MTV applications. However, works related to the temperature dependence of these tracers luminescent properties in rarefied conditions are scarce. Therefore, in this study, a preliminary investigation is carried on the behavior of these tracers molecules at different conditions of pressure and temperature. This study will be helpful in assessing the feasibility of these molecules as molecular tracers to map temperature profiles in gaseous rarefied flows.