Fluid Properties Measurements Using Wavelength Modulation Spectroscopy with First Harmonic Detection

An apparatus and method for monitoring gas velocity, temperature, and pressure in combustion systems and flow devices, in particular at inlets and isolators of scramjet engines. The invention employs wavelength modulation spectroscopy with first harmonic detection and without the need to scan the full absorption spectra

Response of blade-row to upstream vortical disturbance in relative motion

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 1995.Includes bibliographical references (leaves 47-49).by Shin-Juh Chen.M.S

Coupling between fluid dynamics and combustion in a laminar vortex ring

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/76826/1/AIAA-2000-433-168.pd

Laser soot-Mie scattering in a reacting vortex ring

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/76846/1/AIAA-2001-786-760.pd

Combustion Species Sensor for Scramjet Flight Instrumentation

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/76361/1/AIAA-2005-3574-730.pd

Experimental and computational study of fluid dynamics-combustion coupling in a diffusion flame -vortex ring interaction.

Flame-vortex interaction is a canonical configuration that contains the fundamental element of flow, transport and combustion phenomena found in turbulent reacting flows, and provides a means for testing existing models and developing new models for diffusion flames. The configuration used in this study is the first to examine an exothermic reacting vortex ring under microgravity conditions, formed from the rollup of a diffusion flame during formation of a vortex ring composed of both fuel and entrained ambient oxidizer. Experiments and computational studies were conducted to shed light on the effects of chemistry and hydrodynamic parameters on the flame structure and ring dynamics. The dominant effect of combustion heat release was found to be volumetric expansion (dilatation) over enhanced diffusivities due to temperature. Dilatation had a dramatic effect on the ring trajectories which initially provided an increase in ring speed during the early phase and a large reduction in speed in the latter phase of the diffusion flame-vortex ring interaction. Fuel volume was also determined to play a key role in the amount of heat released during the initial phase of interaction. An increase in fuel volume beyond a critical limit set by stoichiometric requirements, while keeping the circulation unchanged, led to a decrease in heat released which resulted in a decrease in ring speed. The effect of nitrogen dilution of propane was mainly a reduction in flame luminosity with little change in the flame structure. In addition, comparisons between propane and ethane cases reveal that radiative heat loss can significantly affect the flame structure and dynamics of reacting vortex rings. Numerical simulations of methane-air chemistry with flamelet chemistry revealed that the OH layer was thicker than the CH and HCO layers. Increasing the ring circulation while keeping the fuel volume constant resulted in an increase of these minor species along the forward stagnation point of the reacting vortex rings. These results should provide the basis for future laser diagnostic studies of certain key aspects of this flame-vortex configuration.Ph.D.Aerospace engineeringApplied SciencesUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/132545/2/9977133.pd

Experiments on Diffusion Flame Structure of a Laminar Vortex Ring

The study of flame-vortex interactions provides one of the means to better understand turbulent combustion, and allows for canonical configurations that contain the fundamental elements found in turbulent flames, These include concentrated vorticity, entrainment and mixing, strain and nonequilibrium phenomena, diffusion and differential diffusion, partial premixing and diluent effects, and heat release effects. In flame- vortex configurations, these fundamental elements can be studied under more controlled conditions than is possible in direct investigations of turbulent flames. Since the paper of Marble, the problem of the flame-vortex interaction has received considerable attention theoretically, numerically and experimentally. Several configurations exist for study of the premixed flame/vortex ring interaction but more limited results have been obtained to date for the diffusion flame/vortex ring case. The setup of Chen and Dahm, which is conceptually similar to that of Karagozian and Manda and Karagozian, Suganuma and Strom where the ring is composed of fuel and air and combustion begins during the ring formation process, is used in the current study. However, it is essential to conduct the experiments in microgravity to remove the asymmetries caused by buoyancy and thus obtain highly symmetric and repeatable interactions. In previous studies it was found that the flame structure of the vortex ring was similar to that obtained analytically by Karagozian and Manda. Dilution of propane with nitrogen led mainly to a reduction in flame luminosities, flame burnout times were affected by both fuel volumes and amount of dilution, and a simple model of the burnout times was developed. In this paper, a discussion on reacting ring displacement and flame burnout time will be given, and the flame structures of vortex rings containing ethane and air will be compared to those of propane reacting in air

Quantitative Species Measurements In Microgravity Combustion Flames

The capability of models and theories to accurately predict and describe the behavior of low gravity flames can only be verified by quantitative measurements. Although video imaging, simple temperature measurements, and velocimetry methods have provided useful information in many cases, there is still a need for quantitative species measurements. Over the past decade, we have been developing high sensitivity optical absorption techniques to permit in situ, non-intrusive, absolute concentration measurements for both major and minor flames species using diode lasers. This work has helped to establish wavelength modulation spectroscopy (WMS) as an important method for species detection within the restrictions of microgravity-based measurements. More recently, in collaboration with Prof. Dahm at the University of Michigan, a new methodology combining computed flame libraries with a single experimental measurement has allowed us to determine the concentration profiles for all species in a flame. This method, termed ITAC (Iterative Temperature with Assumed Chemistry) was demonstrated for a simple laminar nonpremixed methane-air flame at both 1-g and at 0-g in a vortex ring flame. In this paper, we report additional normal and microgravity experiments which further confirm the usefulness of this approach. We also present the development of a new type of laser. This is an external cavity diode laser (ECDL) which has the unique capability of high frequency modulation as well as a very wide tuning range. This will permit the detection of multiple species with one laser while using WMS detection