Blowout and liftoff limits of a hydrogen jet flame in a supersonic, heated, coflowing air stream

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/76310/1/AIAA-1993-446-753.pd

Simultaneous CH planar laser-induced fluorescence and particle imaging velocimetry in turbulent flames

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/77055/1/AIAA-1998-151-822.pd

The study of the turbulent burning velocity by imaging the wrinkled flame surface

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/76129/1/AIAA-2002-482-348.pd

Parallel fuel injection from the base of an extended strut into supersonic flow

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/76778/1/AIAA-1994-711-873.pd

Measured supersonic flame properties - Heat-release patterns, pressure losses, thermal choking limits

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/76611/1/AIAA-24093-582.pd

Spatially resolved mass flux measurements with dual comb spectroscopy

Providing an accurate, representative sample of mass flux across large open areas for atmospheric studies or the extreme conditions of a hypersonic engine is challenging for traditional intrusive or point-based sensors. Here, we demonstrate that laser absorption spectroscopy with frequency combs can simultaneously measure all of the components of mass flux (velocity, temperature, pressure, and species concentration) with low uncertainty, spatial resolution corresponding to the span of the laser line of sight, and no supplemental sensor readings. The low uncertainty is provided by the broad spectral bandwidth, high resolution, and extremely well-known and controlled frequency axis of stabilized, mode-locked frequency combs. We demonstrate these capabilities in the isolator of a ground-test supersonic propulsion engine at Wright-Patterson Air Force Base. The mass flux measurements are consistent within 3.6% of the facility-level engine air supply values. A vertical scan of the laser beams in the isolator measures the spatially resolved mass flux, which is compared with computational fluid dynamics simulations. A rigorous uncertainty analysis demonstrates a DCS instrument uncertainty of ~0.4%, and total uncertainty (including non-instrument sources) of ~7% for mass flux measurements. These measurements demonstrate DCS as a low-uncertainty mass flux sensor for a variety of applications.Comment: Main Text: 15 pages, 7 figure; Supplement: 6 pages, 4 figures; Submitted to Optic

Reaction zone structure and velocity measurements in permanently blue nonpremixed jet flames.

The present work addresses the question of whether the chemical reaction zone within a turbulent, high-Reynolds-number jet flame is thin--and can be modeled using strained wrinkled laminar flamelet theory--or is thick--and must be modeled using distributed reaction zone theory. The region near the wrinkled instantaneous stoichiometric contour in soot-free permanently blue jet flames (mixture fraction between 0.5-0.7) is identified using CH Planar Laser-Induced Fluorescence (PLIF) imaging and the strain on this interface is measured using simultaneous Particle Imaging Velocimetry (PIV) diagnostics. With a separate set of simultaneous images, the relative position of the CH and OH radicals is observed using PLIF. It is found that the CH reaction zone remains thin and rarely exceeds 1 mm, even near the flame tip in a high-Reynolds-number (18,600) jet flame. The mean thickness of the CH reaction layer \rm (\delta \sb{\sc CH}) increases from 0.3 to 0.8 mm in the streamwise direction; this is expected because the scalar dissipation rate is known to decrease with downstream distance and should cause a corresponding increase in \rm \delta\sb{\sc CH}. However, \rm\delta\sb{\sc CH} also increases with jet velocity, which is not predicted by theory. Furthermore, the mean strain rates on the stoichiometric contour increase in the streamwise direction, which is contrary to previous predictions. Thus, strain rate does not, in general, scale with the local dissipation rate in a turbulent flame, and this aspect of the counterflow flow analogy is not valid. It is concluded that unsteady laminar flamelet concepts are consistent with most of the present observations, but a method independent of the local dissipation rate is needed to predict the local strain rate.Ph.D.Aerospace engineeringApplied SciencesUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/130941/2/9825204.pd

Simultaneous CH planar laser-induced fluorescence and particle imaging velocimetry in turbulent nonpremixed flames

=18600). Here, PLIF images reveal a CH layer of thickness typically <1 mm from flame base to tip. Furthermore, in these permanently blue flames, we observe instantaneous flamefront strain rates – derived from the PIV data – in excess of ±10 4  s -1 without flame extinction.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/42155/1/340-66-1-129_80660129.pd