As part of the continued emphasis on fuel tank safety, the Federal Aviation Administration (FAA) has developed a demonstration fuel tank inerting system and has tested it on a NASA-operated Boeing 747 aircraft.To support this, the FAA developed two models to predict both fuel tank oxygen concentration and flammability in an inerted ullage, based on previously developed models and calculations.Laboratory and aircraft test results indicated that the models duplicated measured data trends well and gave predicted peak values with a reasonable degree of accuracy.This allowed the FAA to develop a representative Boeing 747 aircraft flight cycle and give predictions of flammability exposure for the given ullage.The results indicated that the aircraft fuel tank would not be exposed to flammable conditions during the developed flight profile with the represented inerting system even though part of the tank ullage did achieve oxygen concentration levels of approximately 18%.

An approximate method for estimating Jet A fuel vapor composition within a simulated aircraft fuel tank was used for comparisons with previous experimental data. The results were used to convert the data so that it could be used for comparisons with a lower fuel flammability limit. The effect of fuel loading on the predicted vapor species and on the total measured fuel vapor concentrations was discussed. The computed results can be of use in the analysis of the effect of fuel mass loading on work related to the minimum ignition energy.

Existing data from thermocouple probes inserted into fused silica glass rods within an optical fiber draw tower furnace were used for comparisons with modeling predictions. Radiative transport model through the glass was based on the zonal method and a four band model with two absorbing and two non-absorbing bands. The glass rod and thermocouple probe temperature distributions were computed as a coupled conduction-radiation problem within the furnace enclosure. Predicted and measured results were in good agreement in spite to limitations imposed by incomplete knowledge of relevant glass properties and the assumption disuse glass surfaces.

This work summarizes an experimental investigation of the low-temperature (-15 degrees C to 24 degrees C), ambient pressure vaporization of suspended single and multicomponent liquid droplets in an air stream moving at relative velocities between 1 and 3 m/s. The work was motivated by the consideration of droplet vaporization during fuel jettisoning from aircraft, and the majority of data was collected using JP-4 and JP-8 fuels. The results showed preferential vaporization of the lighter components. A simple semiempirical predictive approach based on spherical symmetric vaporization and rapid mixing within the droplets was in good agreement with the experimental data.

The present work is motivated by the current need of increasing the yield of optical fiber drawing by using high draw speeds. For such conditions the preform feed rate through the draw tower furnace can affect the heat transfer to the preform rod and as a consequence the formation of the neckdown. In the present work temperature distributions along the axis of stationary as well as moving graphite and fused silica rods inserted in a fiber optic draw tower furnace was found experimentally. Experimental data clearly showed that the thermal lag increased at higher draw speeds. Implications of this to high speed fiber drawing are highlighted. Measured temperatures were compared with numerically computed temperature distributions in moving rods. Excellent agreement was found between the temperature recorded in moving graphite rod experiments and the computed temperatures which validated the furnace temperature profile found in the previous work. However, for glass rods the computed temperature lag was greater than the measured temperature lag. The difference between computed glass temperatures and those measured using a thermocouple was explained using a simplified modeling taking into account spectrally selective radiation properties of glass.

Study of the thermal transport and material flow processes associated with the drawing of optical fiber in a graphite draw furnace require modeling of the radiative heat transfer from the furnace wall. Previous work has shown that accurate knowledge of the furnace heater element axial temperature distribution is essential for proper modeling of the radiative transfer process. The present work is aimed at providing this information, as well as generating a set of data for the study of radiation exchange in the furnace cavity. The experimental procedure involved mounting rods of different materials and diameters and feeding them axially within the furnace cavity. Each rod was instrumented with a C type thermocouple inserted through an axial hole along the centerline. The temperature measurements were used along with a numerical model for radiative-convective heat transfer in the furnace in order to obtain the furnace temperature profile. This is an inverse problem since the centerline temperature in the rod is known whereas the furnace thermal conditions are not known. The results obtained using the graphite rods suggest that the furnace temperature is not affected by rod size. A correlation equation was developed for future modeling use.

Study of the thermal transport and material flow processes associated with the drawing of optical fiber in a graphite draw furnace requires modeling of the heat transfer from the furnace wall. Previous work has shown that accurate knowledge of the furnace heater element axial temperature distribution is essential for proper modeling of the radiative transfer process. The present work is aimed at providing this information, as well as generating a set of data for the study of radiation exchange in the furnace cavity. The experimental procedure involved measuring the centerline temperature distribution in graphite and fused silica rods inserted into an optical fiber draw tower furnace. The temperature measurements were then used along with a model for radiative-convective heat transfer in the furnace in order to obtain the furnace temperature profile. This is an inverse problem since the centerline temperature in the rod is known whereas the furnace thermal conditions are not. The results obtained showed that the furnace temperature distribution was independent of rod material and size. The shape of the computed temperature distributions suggest that they can be well represented by a Gaussian function.

The work is a laboratory investigation of the effect of different liquids and liquid flow rates on the metal temperature of a gas turbine T vaporizer. Most of the experimentation was carried out using JP5. A limited number of runs using Diesel Fuel Marine and calibration runs using water provided additional data for different fluids. Conditions that approach local liquid depletion inside the vaporizer were identified by monitoring local overheating of the vaporizer metal. Because of apparatus limitations, testing was carried out only at vaporizer pressure and liquid flow rates approaching idle engine operation. An experimental correlation was developed allowing estimation of the mean vaporizer temperature as a function of input conditions and fluid properties.

Technical Briefs Forced Convective Cooling of Optical Fiber During Drawing Process S. Roy Choudhury, S. Roy Choudhury Department of Mechanical and Aerospace Engineering, Rutgers University, New Brunswick, NJ 08903 Search for other works by this author on: This Site PubMed Google Scholar Y. Jaluria, Y. Jaluria Department of Mechanical and Aerospace Engineering, Rutgers University, New Brunswick, NJ 08903 Search for other works by this author on: This Site PubMed Google Scholar T. Vaskopoulos, T. Vaskopoulos Department of Mechanical and Aerospace Engineering, Rutgers University, New Brunswick, NJ 08903 Search for other works by this author on: This Site PubMed Google Scholar C. E. Polymeropoulos C. E. Polymeropoulos Department of Mechanical and Aerospace Engineering, Rutgers University, New Brunswick, NJ 08903 Search for other works by this author on: This Site PubMed Google Scholar Author and Article Information S. Roy Choudhury Department of Mechanical and Aerospace Engineering, Rutgers University, New Brunswick, NJ 08903 Y. Jaluria Department of Mechanical and Aerospace Engineering, Rutgers University, New Brunswick, NJ 08903 T. Vaskopoulos Department of Mechanical and Aerospace Engineering, Rutgers University, New Brunswick, NJ 08903 C. E. Polymeropoulos Department of Mechanical and Aerospace Engineering, Rutgers University, New Brunswick, NJ 08903 J. Heat Transfer. Aug 1994, 116(3): 790-794 (5 pages) https://doi.org/10.1115/1.2910944 Published Online: August 1, 1994 Article history Received: June 1, 1993 Revised: November 1, 1993 Online: May 23, 2008

The present effort addresses the technical issues associated with hydrocarbon fuel jettisoning from aircraft, including the adaptation of an existing aerial application model for pesticide deposition. The analysis produces qualitatively and quantitatively reasonable results both in mutlicomponent evaporation calculations for isolated droplets, as well as fully coupled calculationx of airborne fuel jettisoning. Both classes of computations confirm earlier conclusions that the likely groundfall of JP-8 jet fuel is substantially higher than the more volatile JP-4 jet fuel, and reiterate the need for a careful assessment of the environmental impact of fuel jettisoning events involving JP-8. The preliminary model appears to be a suitable starting point for full-scale development of a flexible, practical fuel jettisoning simulations code.

Liquid particles from the breakup of liquid jets produced by a gas chromatographic syringe autoinjection system were observed and measured experimentally. The particle size depended on the motion of the syringe plunger. Very large, fast-moving particles were observed during accelerating periods of the liquid jet. The injection test chamber temperature affected the downstream particle size by heating the liquid before it left the needle and by evaporation into the hot gas. The particles produced by the water and heptane samples used were large and did not lend themselves to rapid vaporization within the gas stream of the gas chromatographic inlet port. Under such conditions, total sample vaporization must be considered either on the hot inlet port wall or on inserts within the inlet port.

ABSTRACT Commercial multimode optical fibers, coated with aluminum, gold, or polyimide were used in apressure sensor that squeezed the fiber between a serrated disk and a compliant material. The sensor wastested up to 400F, and was found to perform well only in a uniform temperature environment. Differentialthennal expansion within the sensor made the sensor unusable in temperature transients. Preliminary testsshow that mode stripping before the photo-detector can improve the transient temperature response. 1.INTRODUCTION This study is a continuation of the work begun by Ferina et al who were developing a fast response pressure sensor for high temperature environments. They found that it is very difficult to designa microbend sensor for small pressure changes (0 - 5 psi), and that vibrational noise can be quite high for amicrobend sensor. In this study, the operating pressure range was raised to 100 psi so that the microbendforce could be increased, and the classical microbending arrangement of two rows of teeth squeezing ona fiber was replaced by a single row of serrations that squeezed the fiber against a compliant material. Thisarrangement was thought to be less vibration sensitive. The test facility was changed from the shock tubeused by Ferina, to the hydraulic oil facility described in this paper. This facility was not only easier to usebut also more repeatable than the shock tube.

Two versions of a fast-response microbend pressure sensor have been developed for deployment in high temperature environments. Aluminum-coated fiber is used in a drum configuration in the sensors which employ a unique "fingered" flexural diaphragm technique to induce microbend attenuation. A dedicated test facility consisting of a shock tube and customized furnace has been established for high-temperature pressure sensor evaluation. The shock tube delivers reproducible, fast rise-time pressure pulses. Sensor response has been obtained using single mode fiber. The furnace, which has been built around the shock tube, and which maintains a heated environment to 750°C, has not yet been used with the fiber sensors.

A laboratory test apparatus was constructed for assessing the metal temperature and the state of different air-fuel mixtures at the outlet of a gas turbine vaporizer fuel injector. The performance of the apparatus was according to the imposed requirements for idle engine operation. Fuels tested were JP5, JP7, and Diesel Fuel Marine. Data consisted of vaporizer metal temperatures, inlet and exit mixture temperatures, as well as power input to the vaporizer. Photographic observations of the exit mixture showed that the liquid phase consisted of droplets, ligaments, as well as irregularly shaped particles originating as pendant droplets around the vaporizer exit. There was no observable difference between the results for JP5 and JP7. The liquid exit temperature, however, for these two fuels appeared to be lower than that for the diesel fuel. The computed extent of vaporization was in qualitative agreement with the experimental observations.

A novel apparatus for accelerated cooling of optical fiber has been used at different fiber speeds using Nitrogen and Helium as the cooling gases. The gas flow was counter to the direction of the fiber motion inside a small diameter tube. The experimental results show significant improvement over natural cooling, as well as over available transverse cooling.

The minimum spark ignition energy in methaneair mixtures was measured for pressures between 0.1 and 0.4 atm and methane concentrations near the lean ignition limits. Spark gap sizes between 2 and 10 mm and spark durations between 70 and 120 μs and a maximum spark energy of 600 mJ were used to identify lowest ignited methane concentrations. These concentrations were found in good agreement with previous measured lower limits of flammability using similar apparatus.

Pressure and temperature variations which occur during an injection in a gas chromatograph split injection port were measured for different sample sizes, injection port temperatures, solvents, injection port inserts, and split flow-rates. A control volume analysis of the injection process was developed to predict the pressure, temperature and split ratio variations during and after the injection. Comparison of the predicted pressure and temperature results with the experimental measurements was satisfactory. An example is presented demonstrating how the model can be used to predict the quantitative error in a split injection port.

A holographic technique was employed to measure in situ the droplet size distribution and the fuel-air mass ratio in a flowing stream of kerosene spray. The holographic measurement of the fuel-to-air ratio was in good agreement with that obtained by direct fuel and air flow rate measurements. The Upper Limit Log-Probability distribution function provided a satisfactory correlation of the droplet size data.

The droplet size distribution in various experimental air-fuel sprays was measured using a holographic method. There was good agreement between upper-limit log-normal velocity distribution functions and the droplet size data. The Sauter mean diameter, maximum droplet diameter, and air-fuel ratio were also well represented by the data. Measurements of burning velocities in the sprays tested were compared with calculated predictions, and the results were satisfactory. Approximate burning velocities in modified fuel sprays produced under wind shear conditions were also calculated. (auth)