IMAGING FOURIER-TRANSFORM SPECTROMETRY FOR PLUME DIAGNOSTICS AND CODE VALIDATION

Abstract

Laminar and turbulent flow fields found in smokestacks, flames, jet engine exhaust, and rocket plumes are of practical and academic interest and could greatly benefit from spatially resolved spectral measurements. Key physical flow field parameters such as temperature and species concentrations can be extracted from spectral observations. Spectral images of flow fields produce rich information for plume diagnostics and could be used to validate next-generation plume codes. Laser-based diagnostics are typically used to measure temperatures, concentrations, and flow velocities. Unfortunately, these laser-based techniques are largely confined to a laboratory environment, and tracking multiple species concentrations is complicated due to the limited bandwidth of tunable laser sources. The advantage of a passive sensor with high resolution across a broad bandwidth would make an imaging Fourier-transform spectrometer (IFTS) an attractive instrument for flow diagnostics, particularly when the flow field of interest cannot be studied in a laboratory. In this paper, we present an overview of IFTS and its uses for flow visualization and combustion diagnostics in various plumes. Examples from recent measurements of laminar flames and jet engine exhaust will be presented.