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heaters providing the heat to be transferred. Start-up and heat transfer of over 300 W was demonstrated with both steady and variable condenser sink temperatures. Radiator sink temperatures ranged from a high of approximately 273 K, to a low of approximately 83 K, and the system was held at a constant operating temperature of 278 K throughout most of the testing. A novel LHP temperature control methodology using both temperature-controlled electrical resistance heaters and a small VCHP was demonstrated. This paper describes the system and the tests performed and includes a discussion of the test results. Author Temperature Control; Vacuum; Vacuum Chambers; Heat Pipes; Performance Tests; Test Stands 20030025282 NASA Goddard Space Flight Center, Greenbelt, MD, USA Investigation into the Micro-Gravity Effects on Two-Phase Spray Thermophysics Yerkes, Kirk; Michalak, Travis; Silk, Eric; Swanson, Ted; McQuillen, John; Golliher, Eric; [2002]; 23 pp.; In English; International Two-Phase Thermal Control Technology Workshop, 24-26 Sep. 2002; No Copyright; Avail: CASI; A03, Hardcopy This viewgraph presentation provides information on the effects of microgravity on a spray system being developed for thermal management in aerospace environments. The presentation addresses trends in thermal technology and NASA’s thermal technology needs, thermophysics experiments conducted in microgravity, and equipment for the experiments. Author Temperature Control; Thermodynamics; Sprayers; Microgravity 20030025342 NASA Glenn Research Center, Cleveland, OH, USA Time and Space Resolved Heat Transfer Measurements Under Nucleate Bubbles with Constant Heat Flux Boundary Conditions Myers, Jerry G.; Hussey, Sam W.; Yee, Glenda F.; Kim, Jungho; [2003]; 3 pp.; In English; 2003 ASME Summer Heat Transfer Conference, 21-23 Jul. 2003, Las Vegas, NV, USA; Original contains black and white illustrations Contract(s)/Grant(s): 22-400-32-30-06 Report No.(s): Paper HT2003-40591; E-13877; Copyright; Avail: CASI; A01, Hardcopy Investigations into single bubble pool boiling phenomena are often complicated by the difficulties in obtaining time and space resolved information in the bubble region. This usually occurs because the heaters and diagnostics used to measure heat transfer data are often on the order of, or larger than, the bubble characteristic length or region of influence. This has contributed to the development of many different and sometimes contradictory models of pool boiling phenomena and dominant heat transfer mechanisms. Recent investigations by Yaddanapyddi and Kim and Demiray and Kim have obtained time and space resolved heat transfer information at the bubble/heater interface under constant temperature conditions using a novel micro-heater array (10x10 array, each heater 100 microns on a side) that is semi-transparent and doubles as a measurement sensor. By using active feedback to maintain a state of constant temperature at the heater surface, they showed that the area of influence of bubbles generated in FC-72 was much smaller than predicted by standard models and that micro-conduction/micro-convection due to re-wetting dominated heat transfer effects. This study seeks to expand on the previous work by making time and space resolved measurements under bubbles nucleating on a micro-heater array operated under constant heat flux conditions. In the planned investigation, wall temperature measurements made under a single bubble nucleation site will be synchronized with high-speed video to allow analysis of the bubble energy removal from the wall. Author Heat Transfer; Temperature Measurement; Time Measurement; Nucleation; Bubbles; Heat Flux; Boundary Conditions 20030025361 NASA Goddard Space Flight Center, Greenbelt, MD, USA Low Frequency High Amplitude Temperature Oscillations in Loop Heat Pipe Operation Ku, Jentung; Rodriquez, Jose; Simpson, Alda D., Technical Monitor; July 2003; 26 pp.; In English; 33rd ICES Conference, 7-10 Jul. 2003, Vancouver, BC, Canada; No Copyright; Avail: CASI; A03, Hardcopy This paper presents a theory that explains low frequency, high amplitude temperature oscillations in loop heat pipe (LHP) operation. Oscillations of the CC temperature with amplitudes on the order of tens of degrees Kelvin and periods on the order of hours have been observed in some LHPs during ambient testing. There are presently no satisfactory explanations for such a phenomenon in the literature. It is well-known that the operating temperature of an LHP with a single evaporator is governed by the compensation chamber (CC) temperature, which in turn is a function of the evaporator heat load, sink temperature, and ambient temperature. As the operating condition changes, the CC temperature will change during the transient but eventually reach a new steady temperature. Under certain conditions, however, the LHP never really reaches a true steady state, but 49
instead displays an oscillatory behavior. The proposed new theory describes why low frequency, high amplitude oscillations may occur when the LHP has a low evaporator power, a low heat sink temperature (below ambient temperature), and a large thermal mass attached to the evaporator. When this condition prevails, there are some complex interactions between the CC, condenser, thermal mass and ambient. The temperature oscillation is a result of the large movement of the vapor front inside the condenser, which is caused by a change in the net evaporator power modulated by the large thermal mass through its interaction with the sink and CC. The theory agrees very well with previously published test data. Effects of various parameters on the amplitude and frequency of the temperature oscillation are also discussed. Author Low Frequencies; Amplitudes; Temperature Measurement; Operating Temperature; Loops; Heat Pipes; Display Devices 20030025712 Analytical Services and Materials, Inc., Hampton, VA, USA Source Term Model for an Array of Vortex Generator Vanes Buning, P. G., Technical Monitor; Waithe, Kenrick A.; January 03, 2003; 23 pp.; In English; Original contains color illustrations Contract(s)/Grant(s): NASA Order L-70750-D; RTOP 714-05-10-02 Report No.(s): NASA/CR-2003-212157; NAS 1.26:212157; No Copyright; Avail: CASI; A03, Hardcopy A source term model was developed for numerical simulations of an array of vortex generators. The source term models the side force created by a vortex generator being modeled. The model is obtained by introducing a side force to the momentum and energy equations that can adjust its strength automatically based on a local flow. The model was tested and calibrated by comparing data from numerical simulations and experiments of a single low-pro<strong>file</strong> vortex generator vane, which is only a fraction of the boundary layer thickness, over a flat plate. The source term model allowed a grid reduction of about seventy percent when compared with the numerical simulations performed on a fully gridded vortex generator without adversely affecting the development and capture of the vortex created. The source term model was able to predict the shape and size of the stream wise vorticity and velocity contours very well when compared with both numerical simulations and experimental data. Author Vortex Generators; Computational Fluid Dynamics; Flow Velocity; Numerical Flow Visualization; Direct Numerical Simulation; Mathematical Models; Fluid Flow 20030025722 NASA Glenn Research Center, Cleveland, OH, USA Demonstration of Separation Control Using Glow-Discharge Plasma Actuators Hultgren, Lennart S.; Ashpis, David E.; January 2003; 16 pp.; In English; Copyright; Avail: CASI; A03, Hardcopy Active flow control of boundary-layer separation using glow-discharge plasma actuators is studied experimentally. Separation is induced on a flat plate installed in a closed-circuit wind tunnel by a shaped insert on the opposite wall. The flow conditions represent flow over the suction surface of a modem low-pressure-turbine airfoil. The Reynolds number, based on wetted plate length and nominal exit velocity, is varied from 50,000 to 300,000, covering cruise to takeoff conditions. Low (0.2\%) and high (2.5\%) free-stream turbulence intensities are set using passive grids. A spanwise-oriented phased-plasmaarray actuator, fabricated on a printed circuit board, is surface-flush-mounted upstream of the separation point and can provide forcing in a wide frequency range. Static surface pressure measurements and hot-wire anemometry of the base and controlled flows are performed and indicate that the glow-discharge plasma actuator is an effective device for separation control. Author Actuators; Glow Discharges; Plasmas (Physics); Active Control; Wind Tunnel Tests; Separated Flow; Fabrication 20030027075 NASA Glenn Research Center, Cleveland, OH, USA Glow Discharge Plasma Active Control of Separation at Low Pressure Turbine Conditions Hultgren, Lennart S.; Ashpis, David E.; [2002]; 15 pp.; In English; American Physical Society Division of Fluid Dynamics 55th Annual Meeting, 24-26 Nov. 2002, Dallas, TX, USA; Original contains black and white illustrations; No Copyright; Avail: CASI; A03, Hardcopy Active flow control of boundary-layer separation using glow-discharge plasma actuators is studied experimentally. Separation is induced on a flat plate installed in a closed-circuit wind tunnel by a shaped insert on the opposite wall. The flow conditions represent flow over the suction surface of a modern low-pressure-turbine airfoil. The Reynolds number, based on wetted plate length and nominal exit velocity, is varied from 50,000 to 300,000, covering cruise to takeoff conditions. Low (0.2\%) and high (2.5\%) free-stream turbulence intensities are set using passive grids. The base flow includes closed 50
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NASA STI Program ... in Profile Sin
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NASA STI Availability Information N
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as CIAO/SDP software developers, we
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Exploration Rover (MER) expeditions
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62 COMPUTER SYSTEMS Includes comput
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data in guard cells leads to the pr
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71 ACOUSTICS Includes sound generat
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20030025751 NASA Langley Research C
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analyzed using quantum kinetic theo
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Science Through ARts (STAR) is an e
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20030022798 California Inst. of Tec
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mostly at intermediate velocities.
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close to the spacecraft. We then us
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This source had been a bright persi
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the X-ray properties of the cluster
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We revise the physics of primary el
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size of the gullies in relation to
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92 SOLAR PHYSICS Includes solar act
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society, GISS is part of the Earth
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Initial Operation and Checkout of S
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ATMOSPHERIC EFFECTS The Sun’s Imp
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Effect of a BN Interphase that Debo
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Scalability of a Low-Cost Multi-Ter
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DATA TRANSMISSION Reliable Transpor
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Atomic Data for the K-Vacancy State
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FORMATION FLYING A Nonlinear, Six-D
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HIGH TEMPERATURE Alumina Volatility
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Atomic Data for the K-Vacancy State
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MATRICES (MATHEMATICS) A Time Integ
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NASA’s Sentinels Monitoring Weath
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PACIFIC OCEAN Tropospheric Ozone Ov
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PROVING Experimental Verification o
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SACCHAROMYCES Redundancies in Large
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SOLAR CORONA Are CME ‘interaction
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STANDARDS NASA GSFC Mechanical Engi
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TENSILE STRESS Temperature Dependen
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TYPE 3 BURSTS Energetic Particle Pr
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Rayleigh-Taylor Gravity Waves and Q
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Balagadde, Frederick The Electrical
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Casey, Carolyn A. Systems Engineeri
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Donnelly, Michael Performance of th
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Gliebe, Philip Recent Progress in E
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Hughes, S. P. Primer Vector Optimiz
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Kirk, C. Laurence Effective Frequen
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Luckring, J. M. Transonic Reynolds
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Naasz, Bo J. Integrated Orbit and A
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Raffaelle, Ryne Future Photovoltaic
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Shirron, Peter J. A Cryogenic, Insu
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Urban and Rural Ozone Collect over
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Xu, Yun-Jun Coupled Attitude and Or
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