An Experimental and Numerical Study of a Supersonic Burner for CFD Model Development

A laboratory scale supersonic burner has been developed for validation of computational fluid dynamics models. Detailed numerical simulations were performed for the flow inside the combustor, and coupled with finite element thermal analysis to obtain more accurate outflow conditions. A database of nozzle exit profiles for a wide range of conditions of interest was generated to be used as boundary conditions for simulation of the external jet, or for validation of non-intrusive measurement techniques. A set of experiments was performed to validate the numerical results. In particular, temperature measurements obtained by using an infrared camera show that the computed heat transfer was larger than the measured value. Relaminarization in the convergent part of the nozzle was found to be responsible for this discrepancy, and further numerical simulations sustained this conclusion

Temperature and water measurements in flames using 1064 nm Laser-Induced Grating Spectroscopy (LIGS)

Laser-Induced Grating Spectroscopy (LIGS) is applied to premixed CH4/ air laminar flat flames under operating pressures of 1 to 6 bar. For the first time, temperature and water concentration have been acquired simultaneously in a reacting flow environment using LIGS. A 1064 nm pulsed laser is used as pump to generate a temporary stationary intensity grating in the probe volume. Water molecules in the flame products absorb the laser energy and generate a thermal grating if sufficiently high energies are delivered by the laser pulses, here more than 100 mJ per pulse. Such energies allow the electric field to polarize the dielectric medium, resulting in a detectable electrostrictive grating as well. This creates LIGS signals containing both the electrostrictive and the thermal contributions. The local speed of sound is derived from the oscillation frequency of LIGS signals, which can be accurately measured from the single shot power spectrum. Data show that the ratio between the electrostrictive and the thermal peak intensities is an indicator of the local water concentration. The measured values of speed of sound, temperature, and water concentration in the flames examined compare favorably with flame simulations with Chemkin, showing an estimated accuracy of 0.5 to 2.5% and a precision of 1.4-2%. These results confirm the potential for 1064-nm LIGS-based thermometry for high-precision temperature measurements of combustion processes.Qualcomm, EPSRC, KAUS

CARS Temperature Measurements in a Combustion-Heated Supersonic Jet

Measurements were made in a combustion-heated supersonic axi-symmetric free jet from a nozzle with a diameter of 6.35 cm using dual-pump Coherent Anti-Stokes Raman Spectroscopy (CARS). The resulting mean and standard deviation temperature maps are presented. The temperature results show that the gas temperature on the centerline remains constant for approximately 5 nozzle diameters. As the heated gas mixes with the ambient air further downstream the mean temperature decreases. The standard deviation map shows evidence of the increase of turbulence in the shear layer as the jet proceeds downstream and mixes with the ambient air. The challenges of collecting data in a harsh environment are discussed along with influences to the data. The yield of the data collected is presented and possible improvements to the yield is presented are discussed

Simultaneous Temperature and Velocity Measurements in a Large-Scale, Supersonic, Heated Jet

Two laser-based measurement techniques have been used to characterize an axisymmetric, combustion-heated supersonic jet issuing into static room air. The dual-pump coherent anti-Stokes Raman spectroscopy (CARS) measurement technique measured temperature and concentration while the interferometric Rayleigh scattering (IRS) method simultaneously measured two components of velocity. This paper reports a preliminary analysis of CARS-IRS temperature and velocity measurements from selected measurement locations. The temperature measurements show that the temperature along the jet axis remains constant while dropping off radially. The velocity measurements show that the nozzle exit velocity fluctuations are about 3% of the maximum velocity in the flow

Resolution of Clinical Signs in Trauma Intensive Care Unit Patients Following Diagnosis of Ventilator-Associated Pneumonia

PURPOSE: The ATS/IDSA Ventilator-Associated Pneumonia (VAP) guidelines suggest that clinical improvement of VAP should be apparent within 3-6 days. Anecdotally, such improvement has not been noted in trauma patients at our institution. The current study was conducted to evaluate resolution of clinical signs of VAP following diagnosis. METHODS: Critically injured adults admitted to the trauma intensive care unit (TICU) from 6/1/06-12/31/07 and subsequently diagnosed with VAP were retrospectively reviewed. Clinical signs, including derangements of maximum temperature (Tmax), white blood cell (WBC) count and Pa02/FiO2, were evaluated on days 1-16 following VAP diagnosis. Data are presented as mean ± SD unless otherwise stated. Clinical parameters following VAP were compared using repeated measures ANOVA with the Tukey test for multiple comparisons. RESULTS: A total of 82 patients were identified. Data for the 34 patients without concurrent infections are presented. Demographic data include: Age 46 ± 17 years; 71% males; 94% blunt trauma; median (IQR) Injury Severity Score 29.5 (24 to 38); duration of mechanical ventilation 33 ± 27 days; ICU length of stay (LOS) 39 ± 25 days; hospital LOS 53 ± 33 days. Clinical signs following VAP diagnosis (Figure): Tmax (°F): Day 1=101.8 ± 1.3, Day 3=101.1 ± 1.1, Day 6=101.1 ± 1.4, Day 16=100.1 ± 3. Compared to Day 1, there was a significant reduction in Tmax at Days 10, 11, 12, 13, 14 and 16 (p \u3c 0.05 for all). WBC count (cells/μL): Day 1=12.9 ± 5, Day 3=13.7 ± 5, Day 6=14.4 ± 5, Day 16=13.8 ± 6. There was no significant difference in WBC count on Days 1-16 (p=0.42). PaO2/FiO2: Day 1=232 ± 108, Day 3=200 ± 87, Day 6=218 ± 104, Day 16=246 ± 126. Differences in PaO2/FiO2 on Days 1-16 did not reach statistical significance (p=0.06). CONCLUSIONS: In trauma patients, improvement of clinical parameters following diagnosis of VAP is delayed beyond the 3-6 day timeframe suggested in the ATS/IDSA guidelines. Alternative methods for determining resolution of VAP in trauma patients should be investigated. METHODS INTRODUCTIO

Resolution of Clinical and Laboratory Abnormalities after Diagnosis of Ventilator-Associated Pneumonia in Trauma Patients

Background: Guidelines advise that patients with ventilator-associated pneumonia (VAP) should respond clinically by Day 3 of antibiotics. White blood cell (WBC) count, maximum temperature (Tmax), and PaO2:FIO2 ratio are all said to respond significantly by Day 6. Resolution of abnormalities has not been evaluated in trauma patients. Methods: Retrospective review of trauma patients with VAP. The WBC count, Tmax, and PaO2:FIO2 were evaluated for 16 days after diagnosis. Patients were grouped into uncomplicated VAP, complicated VAP (those with inadequate empirical therapy [IEAT], VAP relapse/superinfection, or acute respiratory distress syndrome), and concurrent infection +VAP (those also infected at another site). Results: There were 126 patients (uncomplicated VAP= 29, complicated VAP = 69, and concurrent infection + VAP = 28). The mean Tmax in patients with uncomplicated VAP decreased significantly from diagnosis to Day 4 (Day 1: 39 – 0.5°C vs. Day 4: 38.6 – 0.7°C; p = 0.028) but never normalized. Their WBC counts and PaO2:FIO2 did not change significantly over the 16-day follow-up and never normalized.When comparing the three groups, the probability of resolving all three abnormalities was not different (p = 0.5). Conclusions: Clinical and laboratory abnormalities in critically injured patients with VAP do not resolve as quickly as suggested in the guidelines. Future studies should evaluate new methods to determine the response to antibiotic therapy in critically injured patients with VAP

Mobile CARS - IRS Instrument for Simultaneous Spectroscopic Measurement of Multiple Properties in Gaseous Flows

This paper describes a measurement system based on the dual-pump coherent anti-Stokes Raman spectroscopy (CARS) and interferometric Rayleigh scattering (IRS) methods. The IRS measurement is performed simultaneously with the CARS measurement using a common green laser beam as a narrow-band light source. The mobile CARS-IRS instrument is designed for the use both in laboratories as well as in ground-based combustion test facilities. Furthermore, it is designed to be easily transported between laboratory and test facility. It performs single-point spatially and temporally resolved simultaneous measurements of temperature, species mole fraction of N2, O2, and H2, and two-components of velocity. A mobile laser system can be placed inside or outside the test facility, while a beam receiving and monitoring system is placed near the measurement location. Measurements in a laboratory small-scale Mach 1.6 H2-air combustion-heated supersonic jet were performed to test the capability of the system. Final setup and pretests of a larger scale reacting jet are ongoing at NASA Langley Research Center s Direct Connect Supersonic Combustor Test Facility (DCSCTF)

Cryopreservation and vitrification of fish semen: a review with special emphasis on marine species

Semen conservation methods have been extensively studied for fish species over the last 60years. Cryopreservation techniques can be divided into two types: one with slow cooling rates like traditional freezing and the other with ultrarapid rates as used in vitrification. These protocols increase the time over which semen samples can be used for reproduction or sperm quality analysis. Marine fish possess greater resistance than freshwater species to variations in osmolality. This favours the application of these methods, which produce better results after thawing and offer high biotechnological potential for aquaculture. In the last 15years, sperm cryopreservation studies have been carried out in 32 marine species, but there are few analyses of the effects of freezing on the morphology and physiology of sperm cells. The object of this review was to provide recent data on semen cryopreservation in marine fish species and to suggest variables which may be applied in future research

Childhood versus adulthood-onset autoinflammatory disorders: myths and truths intertwined

Autoinflammatory disorders are characterized by spontaneous episodes of systemic inflammation deriving from inherited defects of the innate immune system. Childhood is usually the lifetime involved in most inherited autoinflammatory disorders, but a moderate number of patients may experience disease onset during adulthood. Herein we report our experience in the clinical and genetic approach to the diagnosis of autoinflammatory disorders in regard of the first 500 pediatric and adult patients evaluated during the period 2007-2012 in our Center, due to histories of periodically-recurring inflammatory attacks, giving emphasis to the differences observed according to patients'age and to the most relevant data differentiating child and adult-onset autoinflammatory disorders in the medical literature