Recent developments in laser diagnostics at the stanford high temperature gasdynamics laboratory

Abstract

Recent development of planar laser-induced fluorescence (PLIF) at our laboratory has been directed toward improving both the qualitative and quantitative aspects of PLIF-based flow visualization of gases. Important goals have been increased spatial resolution, higher signal-to-noise ratio measurements, and demonstration of quantitative applications. In this context, we report on two applications of PLIF to turbulent jets. Mixture fraction measurements in non-reacting round jets of nitrogen seeded with biacetyl are extracted from a set of 83 PLIF images, recorded with a cooled CCD camera. For certain magnifications, the spatial fidelity of the images is sufficient to resolve all the turbulence scales in the jet. PLIF images of OH, detected with an intensified video format CCD camera, are used to study the spatial structure of a turbulent non-premixed hydrogen jet flame burning in air. Both detection systems are capable of acquiring high signal and spatial quality images. As a means of characterizing the jets, various image processing algorithms are applied to the data, including statistical analysis, calculation of spatial gradients and spatial correlation techniques. Results from both experiments substantiate a model of mixing which involves rapid mixing of entrained fluid and the importance of large scale structures.Recent development of planar laser-induced fluorescence (PLIF) at our laboratory has been directed toward improving both the qualitative and quantitative aspects of PLIF-based flow visualization of gases. Important goals have been increased spatial resolution, higher signal-to-noise ratio measurements, and demonstration of quantitative applications. In this context, we report on two applications of PLIF to turbulent jets. Mixture fraction measurements in non-reacting round jets of nitrogen seeded with biacetyl are extracted from a set of 83 PLIF images, recorded with a cooled CCD camera. For certain magnifications, the spatial fidelity of the images is sufficient to resolve all the turbulence scales in the jet. PLIF images of OH, detected with an intensified video format CCD camera, are used to study the spatial structure of a turbulent non-premixed hydrogen jet flame burning in air. Both detection systems are capable of acquiring high signal and spatial quality images. As a means of characterizing the je...