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At least 109 records · Page 6

Comparison of thin-film resistance heat-transfer gages with thin-skin transient calorimeter gages in conventional hypersonic wind tunnels

Thin film gages deposited at the stagnation region of small (8.1-mm-diameter) hemispheres and gages mounted flush with the surface of a sharp-leading-edge flat plate were tested in the Langley continuous-flow hypersonic tunnel and in the Langley hypersonic CF4 tunnel. Two substrate materials were tested, quartz and a machinable glass-ceramic. Small hemispheres were also tested utilizing the thin-skin transient calorimeter technique usually employed in conventional tunnels. One transient calorimeter model was a thin shell of stainless steel, and the other was a thin-skin insert of stainless steel mounted into a hemisphere fabricated from a machinable-glass-ceramic. Measured heat-transfer rates from the various hemispheres were compared with one another and with predicted rates. The results demonstrate the feasibility and advantages of using-film resistance heat-transfer gages in conventional hypersonic wind tunnels over a wide range of conditions.

Miller, C. G., III↗

High-temperature containerless calorimeter

A high-temperature (greater than 1500 K) containerless calorimeter is described and its usefulness demonstrated. The calorimeter uses the technique of omnidirectional electron bombardment of pendant drops to achieve an isothermal test environment. The small heat input into the sample (i.e., 15-50 W) can be controlled and measured. The apparatus can be used to determine the total hemispherical emissivity, specific heat, heat of fusion, surface tension, and equilibrium melting temperature of small molten drops in the temperature range of 1500 to 3500 K. The total hemispherical emissivity and specific heat of pure niobium and two alloys of niobium-germanium have been measured in the temperature range of 1700 to 2400 K. As reported in the literature, the total hemispherical emissivity varied as a function of temperature. However, specific heat values for both the pure metal and alloys seem to be independent of temperature. Specific heat for the liquid alloy phase was also measured and compared to the solid phase.

Robinson, M. B.↗

High-pressure calorimeter chamber tests for liquid oxygen/kerosene (LOX/RP-1) rocket combustion

An experimental program was conducted to investigate the rocket combustion and heat transfer characteristics of liquid oxygen/kerosene (LOX/RP-1) mixtures at high chamber pressures. Two water-cooled calorimeter chambers of different combustion lengths were tested using 37- and 61-element oxidizer-fuel-oxidizer triplet injectors. The tests were conducted at nominal chamber pressures of 4.1, 8.3, and 13.8 MPa abs (600, 1200, and 2000 psia). Heat flux Q/A data were obtained for the entire calorimeter length for oxygen/fuel mixture ratios of 1.8 to 3.3. Test data at 4.1 MPa abs compared favorably with previous test data from another source. Using an injector with a fuel-rich outer zone reduced the throat heat flux by 47 percent with only a 4.5 percent reduction in the characteristic exhaust velocity efficiency C* sub eff. The throat heat transfer coefficient was reduced approximately 40 percent because of carbon deposits on the chamber wall.

Masters, Philip A.↗

Observations of cosmic-ray electrons and positrons using an imaging calorimeter

A ballon-borne magnet spectrometer system was flown for 5.5 hr at an altitude of more than 117,00 feet from Prince Albert, Saskatchewan (Canada), on 1989 September 5, when the Newark neutron monitor rate was 2952. The instrument was a modified version of the one used to observe antiprotons in 1979. The most significant modification was the addition of an imaging calorimeter, 7.33 radiation lengths thick. Inclusion of the calorimeter has significantly improved the ability to distinguish electrons and positrons from the other constituents of the cosmic rays. The absolute electron flux has been determined in the energy interval 1.3-26 GeV. The electron spectrum at the top of the atmosphere was found to be J(sub e-) = 177E(exp -(3.15+/-0.13)) electrons/ sq m/(sr s GeV) in the energy range 4.0-26 GeV. Below 4 GeV, the spectrum showed flattening, which is consistent with the effect of solar modulation. The e(+)/(e(+)+e(-)) ratio was found to be (0.11 +/- 0.03) in the energy range 5.2-13 GeV.

Golden, R. L.↗

Metallized Gelled Propellants: Oxygen/RP-1/Aluminum Rocket Engine Calorimeter Heat Transfer Measurements and Analysis

A set of analyses was conducted to determine the heat transfer characteristics of metallized gelled liquid propellants in a rocket engine. The analyses used the data from experiments conducted with a small 30- to 40-lbf thrust engine composed of a modular injector, igniter, chamber and nozzle. The fuels used were traditional liquid RP-1 and gelled RP-1 with 0-wt %, 5-wt%, and 55-wt% loadings of aluminum with silicon dioxide gellant, and gaseous oxygen as the oxidizer. Heat transfer was computed based on measurements using calorimeter rocket chamber and nozzle hardware with a total of 31 cooling channels. A gelled fuel coating formed in the 0-, 5- and 55-wt% engines, and the coating was composed of unburned gelled fuel and partially combusted RP-1. The coating caused a large decrease in calorimeter engine heat flux in the last half of the chamber for the 0- and 5-wt% RP-1/Al. This heat flux reduction effect was analyzed by comparing engine runs and the changes in the heat flux during a run as well as from run to run. Heat transfer and time-dependent heat flux analyses and interpretations are provided. The 5- and 55-wt% RP-1/Al fueled engines had the highest chamber heat fluxes, with the 5-wt% fuel having the highest throat flux. This result is counter to the predicted result, where the 55 wt% fuel has the highest combustion and throat temperature, and therefore implies that it would deliver the highest throat heat flux. The 5-wt% RP-1/Al produced the most influence on the engine heat transfer and the heat flux reduction was caused by the formation of a gelled propellant layer in the chamber and nozzle.

Palaszewski, Bryan↗

The Scintillating Optical Fiber Calorimeter Instrument Performance (SOFCAL)

SOFCAL is a balloon-borne instrument designed to measure the P-He cosmic ray spectra from about 200 GeV/amu - 20 TeV/amu. SOFCAL uses a thin lead and scintillating-fiber ionization calorimeter to measure the cascades produced by cosmic rays interacting in the hybrid detector system. Above the fiber calorimeter is an emulsion chamber that provides the interaction target, primary particle identification and in-flight energy calibration for the scintillating fiber data. The energy measurement technique and its calibration are described, and the present results from the analysis of a 1 day balloon flight will be presented.

Christl, M. J.↗

Imaging Calorimeter for ACCESS Simulations with GEANT/FLUKA

Imaging Calorimeter for ACCESS (ICA) is a candidate of the calorimeter for the NASA's ACCESS program to be flown on the International Space Station. The ICA studies the origin and acceleration mechanism of cosmic rays by measuring the elemental composition of the cosmic rays in the energy up to 10(exp 16) eV. For the past year, Monte Carlo simulation study for the ICA has been conducted using GEANT/FLUKA to predict the detector performance and to design the system for match the scientific objectives. Simulation results will be shown for the detector response and the energy resolution for various configurations.

Watts, John↗

Charge Detector Study for a Thin Sampling Calorimeter for ACCESS

Advanced Cosmic ray Composition Experiment for Space Station (ACCESS) is a NASA's new mission concept that is now being studied. The scientific objective is to measure cosmic ray elemental energy spectra in the energy range from I TeV up to 1000 TeV. ACCESS will carry two instruments and measure the energy and charge of incoming particles. One of these will be a calorimeter with a charge detector. The charge detector will see not only signals from the incident cosmic rays but also signals from radiation backscattered from the calorimeter. In that case, bias information on particle identification is unavoidable. This study shows how much the charge detector will be affected by backscatter and how it can be designed with a minimized effect.

Lee, Jeongin↗

Imaging Calorimeter for ACCESS Simulations with GEANT/FLUKA

Imaging Calorimeter for ACCESS (ICA) is a candidate of the calorimeter for the NASA's ACCESS program. The ICA studies the origin and acceleration mechanism of cosmic rays by measuring the elemental composition of the cosmic rays in the energy up to 10(exp 16) eV. For the past year, Monte Carlo simulation study for the ICA has been conducted to predict the detector performance and to design the system for match the scientific objectives. Simulation results show that the detector response resembles a Gaussian distribution and the energy resolution with ICA can be achieved about 40%. In addition, simulations of the detector's response to an assumed bent power law spectra in the region where the knee occurs have been conducted and clearly show that this detector can provide sufficiently accurate estimates of the spectral parameters that are a science goal of ACCESS.

Lee, Jeongin↗

Advanced Thin Ionization Calorimeter (ATIC) Balloon Experiment

During grant NAG5-5064, Louisiana State University (LSU) led the ATIC team in the development, construction, testing, accelerator validation, pre-deployment integration and flight operations of the Advanced Thin Ionization Calorimeter (ATIC) Balloon Experiment. This involved interfacing among the ATIC collaborators (UMD, NRL/MSFC, SU, MSU, WI, SNU) to develop a new balloon payload based upon a fully active calorimeter, a carbon target, a scintillator strip hodoscope and a pixilated silicon solid state detector for a detailed investigation of the very high energy cosmic rays to energies beyond 10(exp 14) eV/nucleus. It is in this very high energy region that theory predicts changes in composition and energy spectra related to the Supernova Remnant Acceleration model for cosmic rays below the "knee" in the all-particle spectrum. This report provides a documentation list, details the anticipated ATIC science return, describes the particle detection principles on which the experiment is based, summarizes the simulation results for the system, describes the validation work at the CERN SPS accelerator and details the balloon flight configuration. The ATIC experiment had a very successful LDB flight from McMurdo, Antarctica in 12/00 - 1/01. The instrument performed well for the entire 15 days. Preliminary data analysis shows acceptable charge resolution and an all-particle power law energy deposition distribution not inconsistent with previous measurements. Detailed analysis is underway and will result in new data on the cosmic ray charge and energy spectra in the GeV - TeV energy range. ATIC is currently being refurbished in anticipation of another LDB flight in the 2002-03 period.

Wefel, John P.↗

Accelerator Test of an Imaging Calorimeter

The Imaging Calorimeter for ACCESS (ICA) utilizes a thin sampling calorimeter concept for direct measurements of high-energy cosmic rays. The ICA design uses arrays of small scintillating fibers to measure the energy and trajectory of the produced cascades. A test instrument has been developed to study the performance of this concept at accelerator energies and for comparison with simulations. Two test exposures have been completed using a CERN test beam. Some results from the accelerator tests are presented.

Christl, Mark J.↗

The CNO Concentration in Cosmic Ray Spectrum as Measured From The Advanced Thin Ionization Calorimeter Experiment

We present preliminary results on the spectra of CNO nuclei in the cosmic radiation as measured in the first flight of the Advanced Thin Ionization Calorimeter Balloon Experiment (ATIC) which lasted for 16 days, starting in December, 2000 with a launch from McMurdo, Antarctica. ATIC is a multiple, long duration balloon flight, investigation for the study of cosmic ray spectra from below 50 GeV to near 100 TeV total energy, using a fully active Bismuth Germanate (BGO) calorimeter. It is equipped with the first large area mosaic of small fully depleted silicon detector pads capable of charge identification in cosmic rays from H to Fe. As a redundancy check for the charge identification and a coarse particle tracking system, three projective layers of x-y scintillator hodoscopes were employed, above, in the center and below a Carbon interaction "target".

Fazely, A. R.↗

Advanced Thin Ionization Calorimeter (ATIC) Update

The Advanced Thin Ionization Calorimeter (ATIC) experiment is designed to measure the composition and energy spectra of Z = 1 to 28 cosmic rays over the energy range of approximately 10 GeV - 100 TeV. ATIC is comprised of an eight-layer, 18 radiation length deep Bismuth Germanate (BGO) calorimeter, downstream of a 0.75 nuclear interaction length graphite target and an approximately 1 sq m finely segmented silicon charge detector. Interleaved with the graphite layers are three scintillator strip hodoscopes for pre-triggering and tracking. ATIC flew for the first time on a Long Duration Balloon (LDB) launched from McMurdo, Antarctica in January 2001. During its 16-day flight ATIC collected more than 30 million science events, along with housekeeping, calibration, and rate data. This presentation will describe the ATIC data processing, including calibration and efficiency corrections, and show results from analysis of this dataset. The next launch is planned for December 2002.

Ahn, H. S.↗

Detection of High Energy Cosmic Rays with Advanced Thin Ionization Calorimeter, ATIC

The author presents preliminary results of the first flight of the Advanced Thin Ionization Calorimeter (ATIC). ATIC is a multiple, long duration balloon flight, investigation for the study of cosmic ray spectra from below 50 GeV to near 100 TeV total energy, using a fully active Bismuth Germanate (BGO) calorimeter. It is equipped with the first large area mosaic of small fully depleted silicon detector pads capable of charge identification of cosmic rays from H to Fe. As a redundancy check for the charge identification and a coarse particle tracking system, three projective layers of x-y scintillator hodoscopes were employed, above, in the center and below a Carbon interaction 'target'.

Adams, J. H.↗

Relative Abundances and Energy Spectra of C, N, and 0 as Measured by the Advanced Thin Ionization Calorimeter Balloon Experiment

We present results on the spectra and the relative abundances of C, N, and 0 nuclei in the cosmic radiation as measured from the Advanced Thin Ionization Calorimeter Balloon Experiment (ATIC) . The ATIC detector has completed two successful balloon flights from McMurdo, Antarctica lasting a total of more than 35 days. ATIC is designed as a multiple, long duration balloon flight, investigation of the cosmic ray spectra from below 50 GeV to near 100 TeV total energy, using a fully active Bismuth Germanate calorimeter. It is equipped with a large area mosaic of silicon detector pixels capable of charge identification from H to Fe. As a redundancy check for the charge identification and a particle tracking system, three projective layers of x-y scintillator hodoscopes were employed, above, in the middle and below a 0.75 nuclear interaction length graphite target.

Fazely, A. R.↗

Metallized Gelled Propellants: Heat Transfer of a Rocket Engine Fueled by Oxygen/RP-1/Aluminum Was Measured by a Calorimeter

A set of analyses was conducted to determine the heat transfer characteristics of metallized gelled liquid propellants in a rocket engine. These analyses used data from experiments conducted with a small 30- to 40-lbf thrust engine composed of a modular injector, igniter, chamber, and nozzle. The fuels used were traditional liquid RP-1 and gelled RP-1 with 0-, 5-, and 55-wt % loadings of aluminum (Al) with gaseous oxygen as the oxidizer. Heat transfer measurements were made with a calorimeter chamber and nozzle setup that had a total of 31 cooling channels. A gelled fuel coating, composed of unburned gelled fuel and partially combusted RP-1, formed in the 0-, 5- and 55-wt % engines. For the 0- and 5-wt % RP-1/Al, the coating caused a large decrease in calorimeter engine heat flux in the last half of the chamber. This heat flux reduction was analyzed by comparing engine firings and the changes in the heat flux during a firing at NASA Lewis Research Center's Rocket Laboratories. This work is part of an ongoing series of analyses of metallized gelled propellants.

Palaszewski, Bryan A.↗

Thermal Capacitance (Slug) Calorimeter Theory Including Heat Losses and Other Decaying Processes

A mathematical model, termed the Slug Loss Model, has been developed for describing thermal capacitance (slug) calorimeter behavior when heat losses and other decaying processes are not negligible. This model results in the temperature time slope taking the mathematical form of exponential decay. When data is found to fit well to this model, it allows a heat flux value to be calculated that corrects for the losses and may be a better estimate of the cold wall fully catalytic heat flux, as is desired in arc jet testing. The model was applied to the data from a copper slug calorimeter inserted during a particularly severe high heating rate arc jet run to illustrate its use. The Slug Loss Model gave a cold wall heat flux 15% higher than the value of 2,250 W/sq cm obtained from the conventional approach to processing the data (where no correction is made for losses). For comparison, a Finite Element Analysis (FEA) model was created and applied to the same data, where conduction heat losses from the slug were simulated. The heat flux determined by the FEA model was found to be in close agreement with the heat flux determined by the Slug Loss Model.

Hightower, T. Mark↗

Design of Refractory Metal Life Test Heat Pipe and Calorimeter

Heat pipe life tests have seldom been conducted on a systematic basis. Typically, one or more heat pipes are built and tested for an extended period at a single temperature with simple condenser loading. Results are often reported describing the wall material, working fluid, test temperature, test duration, and occasionally the nature of any failure. Important information such as design details, processing procedures, material assay, power throughput, and radial power density are usually not mentioned. We propose to develop methods to generate carefully controlled data that conclusively establish heat pipe operating life with material-fluid combinations capable of extended operation. The test approach detailed in this Technical Publication will use 16 Mo-44.5%Re alloy/sodium heat pipe units that have an approximate12-in length and 5/8-in diameter. Two specific test series have been identified: (1) Long-term corrosion rates based on ASTM-G-68-80 (G-series) and (2) corrosion trends in a cross-correlation sequence at various temperatures and mass fluences based on a Fisher multifactor design (F-series). Evaluation of the heat pipe hardware will be performed in test chambers purged with an inert purified gas (helium or helium/argon mixture) at low pressure (10-100 torr) to provide thermal coupling between the heat pipe condenser and calorimeter. The final pressure will be selected to minimize the potential for voltage breakdown between the heat pipe and radio frequency (RF) induction coil (RF heating is currently the planned method of powering the heat pipes). The proposed calorimeter is constructed from a copper alloy and relies on a laminar flow water-coolant channel design to absorb and transport energy

Martin, J. J.↗