Stabilization zone structure in jet diffusion flames from liftoff toblowout

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/77310/1/AIAA-1989-153-230.pd

The strain exerted by a vortex on a flame - Determined from velocityfield images

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/77209/1/AIAA-1993-362-453.pd

Images of the quenching of a flame by a vortex--To quantify regimes of turbulent combustion

A laminar toroidal vortex is interacted with a laminar premixed flame in order to isolate and to visualize some of the fundamental physics of turbulent combustion. Localized quenching of the flame was observed using planar laser-induced fluorescence imaging of superequilibrium OH molecules in the counterflow flamefront region near the vortex leading edge. A quenching limit curve was measured as a function of vortex size and strength. In the second part of the study, the measurements are combined with concepts proposed by Poinsot, Veynante, and Candel in order to infer the thin flame limit, namely, the onset of distributed reactions, on a classical premixed turbulent combustion regime diagram. The measured thin flame limit indicates when laminar flamelet theories become invalid, since quenching allows hot products and reactants to coexist. Results are compared with the Klimov-Williams criterion. Vortex core diameters were as small as the flame thickness in some cases. The main conclusion is that small vortices are less effective at quenching a flame than was previously believed; therefore the inferred regime within which thin flame theories are valid extends to a turbulence intensity that is more than an order of magnitude larger than that which was previously predicted. Results also indicate that micromixing models, which assume that the smallest eddies exert the largest strain on a flame, are not realistic. Measured trends are in agreement with direct numerical simulations of Poinsot et al., but absolute values differ. The measured vortex Karlovitz number that is required to quench a flame is not constant but decreases by a factor of four as vortex size increases from one to five flame thicknesses. Thin-film pyrometry was used to quantify the radiative heat losses; quenching occurs when the products cool to approximately 1300 K, which is in agreement with stretched laminar flame calculations that include detailed chemistry. The quenching Karlovitz number for propane-air flames differs from that of methane-air flames, indicating the importance of detailed chemistry and transport properties. Flame curvature was observed to cause enhancement (or reduction) of the local reaction rate, depending on the Lewis number, in a manner that is consistent with stretched flame theory.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/30696/1/0000341.pd

Deployment of a Pressure Sensitive Paint System for Measuring Global Surface Pressures on Rotorcraft Blades in Simulated Forward Flight

This paper will present details of a Pressure Sensitive Paint (PSP) system for measuring global surface pressures on the tips of rotorcraft blades in simulated forward flight at the 14- x 22-Foot Subsonic Tunnel at the NASA Langley Research Center. The system was designed to use a pulsed laser as an excitation source and PSP data was collected using the lifetime-based approach. With the higher intensity of the laser, this allowed PSP images to be acquired during a single laser pulse, resulting in the collection of crisp images that can be used to determine blade pressure at a specific instant in time. This is extremely important in rotorcraft applications as the blades experience dramatically different flow fields depending on their position in the rotor disk. Testing of the system was performed using the U.S. Army General Rotor Model System equipped with four identical blades. Two of the blades were instrumented with pressure transducers to allow for comparison of the results obtained from the PSP. Preliminary results show that the PSP agrees both qualitatively and quantitatively with both the expected results as well as with the pressure taps. Several areas of improvement have been indentified and are currently being developed

Dynamic stabilization zone structure of jet diffusion flames from liftoff to blowout

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/76733/1/AIAA-23512-341.pd

Aptamer-based multiplexed proteomic technology for biomarker discovery

Interrogation of the human proteome in a highly multiplexed and efficient manner remains a coveted and challenging goal in biology. We present a new aptamer-based proteomic technology for biomarker discovery capable of simultaneously measuring thousands of proteins from small sample volumes (15 [mu]L of serum or plasma). Our current assay allows us to measure ~800 proteins with very low limits of detection (1 pM average), 7 logs of overall dynamic range, and 5% average coefficient of variation. This technology is enabled by a new generation of aptamers that contain chemically modified nucleotides, which greatly expand the physicochemical diversity of the large randomized nucleic acid libraries from which the aptamers are selected. Proteins in complex matrices such as plasma are measured with a process that transforms a signature of protein concentrations into a corresponding DNA aptamer concentration signature, which is then quantified with a DNA microarray. In essence, our assay takes advantage of the dual nature of aptamers as both folded binding entities with defined shapes and unique sequences recognizable by specific hybridization probes. To demonstrate the utility of our proteomics biomarker discovery technology, we applied it to a clinical study of chronic kidney disease (CKD). We identified two well known CKD biomarkers as well as an additional 58 potential CKD biomarkers. These results demonstrate the potential utility of our technology to discover unique protein signatures characteristic of various disease states. More generally, we describe a versatile and powerful tool that allows large-scale comparison of proteome profiles among discrete populations. This unbiased and highly multiplexed search engine will enable the discovery of novel biomarkers in a manner that is unencumbered by our incomplete knowledge of biology, thereby helping to advance the next generation of evidence-based medicine

THE APPLICATION OF PRESSURE-AND TEMPERATURE- SENSITIVE PAINTS TO AN ADVANCED COMPRESSOR

ABSTRACT An innovative pressure-measurement technique that employs the tools of molecular spectroscopy has been widely investigated by the aerospace community. Measurements are made via oxygen-sensitive molecules attached to the surface of interest as a coating, or paint. The pressure-sensitive-paint (PSP) technique is now commonly used in stationary wind-tunnel tests; this paper presents the use of this technique in advanced turbomachinery applications. New pressureand temperature-sensitive paints (P/TSPs) have been developed for application to a state-of-the-art transonic compressor where pressures up to 1.4 atm and surface temperatures to 90°C are expected for the suction surface of the first-stage rotor. PSP and TSP data images have been acquired from the suction surface of the first-stage rotor at 85% of the corrected design speed for the compressor near-stall condition. A comparison to over-the-rotor pressure transducer measurements will be presented