Visualization of hydrogen injection in a scramjet engine by simultaneous PLIF imaging and laser holographic imaging

Flowfield characterization has been accomplished for several fuel injector configurations using simultaneous planar laser induced fluorescence (PLIF) and laser holographic imaging (LHI). The experiments were carried out in the GASL-NASA HYPULSE real gas expansion tube facility, a pulsed facility with steady test times of about 350 microsec. The tests were done at simulated Mach numbers 13.5 and 17. The focus of this paper is on the measurement technologies used and their application in a research facility. The HYPULSE facility, the models used for the experiments, and the setup for the LHI and PLIF measurements are described. Measurement challenges and solutions are discussed. Results are presented for experiments with several fuel injector configurations and several equivalence ratios

An improved long-wave radiometer

May also be cited as: WHOI-00-13This report describes the development of an improved long-wave radiometer (pyrgeometer) for deployment on ships and buoys. Standard pyrgeometers use a thermopile to measure the temperature gradient between the receiver surface and the instrument case, and thus infer the receiver temperature and incident radiation. The key design change employed in the new radiometer is to remove the thermopile and replace it with a small, glass-encapsulated thermistor to measure the receiver temperature directly. To prove the concept, a prototype radiometer was built and calibrated. It was then deployed outside for a period of a week on the roof of the Clark Laboratory (Quissett Campus, Woods Hole Oceanographic Institution) to demonstrate the feasability of the new concept. Data from the prototype were compared to those from a pair of standard radiometers. The intercomparison shows that the prototype performed surprisingly well. It was able to capture all the variability observed by the standards with only a small bias. The next step in the design process, which has been funded by the National Science Foundation, is to build a rugged version of the prototype that can be deployed in the field.Funding was provided by the Cecil H. and Ida M. Green Technology Innovations Awards Program and the National Science Foundation, Grant OCE98-18470

Decay of Intensity of Certain Hg Lines in an Hg-Ar Discharge

The afterglow of four mercury spectral lines was examined in a mercury-argon electric discharge. The 2537- Å line decays in a complex fashion with three definite modes of decay. The 4077-, 4358-, and 5461- Å lines exhibited an even more complicated decay. These lines exhibited an initial rapid decay followed by an increase in intensity. Finally the intensity of these lines went through two maxima before they decayed in intensity at a slow constant rate. The actual intensity behavior of the 2537- Å line was masked by the imprisonment of resonance radiation. It is postulated that the main processes governing the initial decay were spontaneous radiative decay coupled with electron and ion repopulation of the excited mercury states. The negative decay constant occurring around 100 μsec was probably controlled by the group action of the following processes: ionization of mercury by argon and the resultant recombination, thermalization of discharge electrons and their resultant recombination, and production of electrons by the -interaction of mercury metastable atoms and their recombination. The final slow rate of decay was probably controlled by mercury molecular dissociative recombination

Complications of intracranial pressure monitoring in children with head trauma

Journal ArticleObject. Intracranial pressure (ICP) monitoring has become routine in the management of patients with traumatic brain injury (TBI). Many surgeons prefer to use external ventricular drains (EVDs) over fiberoptic monitors to measure ICP because of the added benefit of cerebrospinal fluid drainage. The purpose of this study was to examine a consecutive series of children with TBI and compare the incidence of complications after placement of an EVD, a fiberoptic intraparencyhmal monitor, or both. Methods. A retrospective chart review was conducted to identify children with TBI who met the criteria for insertion of an ICP monitor. All patients underwent head CT scanning on admission and after placement of an ICP monitor. During a 5-year period 80 children met the criteria for inclusion in the study. Eighteen children (22.5%) underwent EVD placement only, 18 (22.5%) underwent placement of a fiberoptic device only, and 44 (55%) received both. A total of 62 fiberoptic devices (48%) were inserted, and 68 EVDs (52%) were placed. Overall, there was a fourfold increased risk of complications in children who received an EVD compared with those in whom a fiberoptic monitor was placed (p = 0.004). Hemorrhagic complications were detected in 12 (17.6%) of 62 patients who received an EVD compared with four (6.5%) of 62 patients who received a fiberoptic monitor (p = 0.025). Six (8.8%) of 68 EVDs were malpositioned and required replacement; in three (50%) of these cases a hemorrhagic complication occurred. Only one infection was noted in a patient with an EVD (1.5%). Conclusions. In this retrospective cohort of pediatric patients with TBI, complication rates were significantly higher in those receiving EVDs than in those in whom fiberoptic monitors were placed. Although the majority of these complications did not entail clinical sequelae, surgeons should be aware of the different complication rates when choosing the most appropriate device for each patient