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  • Research and Support Facilities (Air)  (4)
  • Aircraft Propulsion and Power  (3)
  • Aircraft Design, Testing and Performance  (1)
  • Fluid Mechanics and Thermodynamics  (1)
  • 1
    Publication Date: 2018-06-05
    Description: NASA Lewis Research Center is a leader in the application of temperature- and pressuresensitive paints (TSP and PSP) in rotating environments. Tests were recently completed on several scale model, high-bypass-ratio turbofans in Lewis' 9- by 15-Foot Low-Speed Wind Tunnel. Two of the test objectives were to determine the aerodynamic and acoustic performance of the fan designs. Using TSP and PSP, researchers successfully achieved fullfield aerodynamic loading profiles. The visualized loading profiles may help researchers identify factors contributing to the fans' performance and to the acoustic characteristics associated with the flow physics on the surface of the blades.
    Keywords: Research and Support Facilities (Air)
    Type: Research and Technology 1997; NASA/TM-20050019500
    Format: application/pdf
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  • 2
    Publication Date: 2018-06-05
    Description: Aircraft icing occurs when a plane flies through a cloud of supercooled water droplets. When the droplets impinge on aircraft components, ice starts to form and accumulate. This accumulation of ice severely increases the drag and lift of the aircraft, and can ultimately lead to catastrophic failures and even loss of life. Knowledge of the air pressures on the surfaces of ice and models in wind tunnels allows researchers to better predict the effects that different icing conditions will have on the performance of real aircraft. The use of pressure-sensitive paint (PSP) has provided valuable information on similar problems in conventional wind tunnel testing. In NASA Lewis Research Center Icing Research Tunnel, Lewis researchers recently demonstrated the world s first application of PSP on actual ice formed on a wind tunnel model. This proof-of-concept test showed that a new paint formulation developed under a grant by the University of Washington adheres to both the ice shapes and cold aluminum models, provides a uniform coating that preserves the detailed ice shape structure, and responds to simulated pressure changes.
    Keywords: Aircraft Design, Testing and Performance
    Type: Research and Technology 1998; NASA/TM-1999-208815
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  • 3
    Publication Date: 2019-07-13
    Description: A prototype light extinction tomography system has been developed for acquiring real-time in-situ icing cloud uniformity and density measurements in the NASA Glenn Research Center's Icing Research Tunnel (IRT). These measurements are currently obtained through periodic manual calibrations of the IRT. These calibrations are time consuming and assume that cloud uniformity and density does not greatly vary between the periodic calibrations. It is envisioned that the new light extinction tomography system will provide the means to make these measurements in-situ in real-time and minimize the need for these manual calibrations. This new system uses the principle of light extinction tomography to measure the spray density and distribution in the test section. The prototype system was installed and successfully demonstrated in the Icing Research Tunnel in early 2018. Data sets were acquired for several standard spray and simulated fault conditions to assess system capability and sensitivity. This paper will describe the prototype light extinction system, the theory behind it, and the results of the demonstration test that was conducted in the IRT.
    Keywords: Research and Support Facilities (Air)
    Type: GRC-E-DAA-TN68961 , AIAA Aviation 2019; Jun 17, 2019 - Jun 20, 2019; Dallas, TX; United States
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  • 4
    Publication Date: 2019-07-13
    Description: NASA Glenn's Propulsion Systems Lab, an altitude engine test facility, generates icing clouds with a spray system. While the spray system is used mostly to create ice crystal clouds (Appendix D/P), the 2017 cloud characterization effort added the requirement to produce exactly supercooled liquid clouds in Appendix C and Appendix O. Success was demonstrated to supercool the largest drops at the warmest conditions, but not freeze out the smallest drops at the coldest conditions. This paper documents primarily the total water content characterization methodology and results from an Iso-Kinetic Probe in ice crystals and Multi-Wire sensor in supercooled liquid, along with the cloud uniformity provided by light extinction tomography. Particle size distribution results from High Speed Imaging probes and a Phase Doppler Interferometer are discussed. Also, a new numerical model for tracking the thermodynamics of the air-drop interactions in PSL from the plenum toward the cloud characterization plane are noted. Both of these latter topic are more fully documented in companion papers.
    Keywords: Research and Support Facilities (Air)
    Type: GRC-E-DAA-TN57012 , AIAA AVIATION Forum; Jun 25, 2018 - Jun 29, 2018; Atlanta, GA; United States
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  • 5
    Publication Date: 2019-07-13
    Description: Pressure-sensitive paint (PSP) has been successfully used to measure global surface pressures on an ice-accreted model in an icing wind tunnel at NASA Glenn Research Center. Until now, the PSP technique has been limited to use in normal wind tunnels and clear flight environments. This is the first known application of PSP directly to ice in subfreezing conditions. Several major objectives were achieved in these tests. The procedure for applying the coating in the subfreezing tunnel environment was verified. Inspection of the painted ice surface revealed that the paint did not alter the original ice shape and adhered well over the entire coated area. Several procedures were used to show that the paint responded to changes in air pressure and that a repeatable pressure-dependent calibration could be achieved on the PSP-coated surfaces. Differences in pressure measurements made simultaneously on the ice and the metal test model are not yet fully understood, and techniques to minimize or correct them are being investigated.
    Keywords: Research and Support Facilities (Air)
    Type: NASA/TM-2000-209942 , E-12190 , NAS 1.15:209942 , Aerospace Sciences; Jan 10, 2000 - Jan 14, 2000; Reno, NV; United States
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  • 6
    Publication Date: 2019-07-13
    Description: The technology of pressure sensitive paint (PSP) is well established in external aerodynamics. In internal flows in narrow channels and in turbomachinery cascades, however, there are still unresolved problems. In particular, the internal flows with complex shock structures inside highly curved channels present a challenge. It is not always easy and straightforward to distinguish between true signals and "ghost" images due to multiple internal reflections in narrow channels. To address some of the problems, investigations were first carried out in a narrow supersonic channel of Mach number 2.5. A single wedge or a combination of two wedges were used to generate a complex shock wave structure in the flow. The experience gained in a small supersonic channel was used for surface pressure measurements on the stator vane of a supersonic throughflow fan. The experimental results for several fan operating conditions are shown in a concise form, including performance map points, midspan static tap pressure distributions, and vane suction side pressure fields. Finally, the PSP technique was used in the NASA transonic flutter cascade to compliment flow visualization data and to acquire backwall pressure fields to assess the cascade flow periodicity. A summary of shortcomings of the pressure sensitive paint technology for internal flow application and lessons learned are presented in the conclusion of the paper.
    Keywords: Aircraft Propulsion and Power
    Type: NASA/TM-2001-211111 , NAS 1.15:211111 , E-12958 , ISABE-2001-1142 , 15th International Symposium on Airbreathing Engines; Sep 02, 2001 - Sep 07, 2001; Bangalore; India
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  • 7
    Publication Date: 2019-07-10
    Description: Thermographic phosphors have been previously demonstrated to provide effective non-contact, emissivity-independent surface temperature measurements. Because of the translucent nature of thermal barrier coatings (TBCs), thermographic-phosphor-based temperature measurements can be extended beyond the surface to provide depth-selective temperature measurements by incorporating the thermographic phosphor layer at the depth where the temperature measurement is desired. In this paper, thermographic phosphor (Y2O3:Eu) fluorescence decay time measurements are demonstrated for the first time to provide through-the-coating-thickness temperature readings up to 1000 C with the phosphor layer residing beneath a 100-Fm-thick TBC (plasma-sprayed 8wt% yttria-stabilized zirconia). With an appropriately chosen excitation wavelength and detection configuration, it is shown that sufficient phosphor emission is generated to provide effective temperature measurements, despite the attenuation of both the excitation and emission intensities by the overlying TBC. This depth-selective temperature measurement capability should prove particularly useful for TBC diagnostics, where a large thermal gradient is typically present across the TBC thickness.
    Keywords: Fluid Mechanics and Thermodynamics
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  • 8
    Publication Date: 2019-07-13
    Description: No abstract available
    Keywords: Aircraft Propulsion and Power
    Type: GRC-E-DAA-TN13236 , International Conference on Advanced Ceramics and Composites (ICACC''14); Jan 25, 2014 - Jan 30, 2014; Daytona Beach, FL; United States
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  • 9
    Publication Date: 2019-07-13
    Description: The development of new active tip clearance control and structural health monitoring schemes in turbine engines and other types of rotating machinery requires sensors that are highly accurate and can operate in a high temperature environment. The use of a microwave sensor to acquire blade tip clearance and tip timing measurements is being explored at the NASA Glenn Research Center. The microwave blade tip clearance sensor works on principles that are very similar to a short range radar system. The sensor sends a continuous microwave signal towards a target and measures the reflected signal. The phase difference of the reflected signal is directly proportional to the distance between the sensor and the target being measured. This type of sensor is beneficial in that it has the ability to operate at extremely high temperatures and is unaffected by contaminants that may be present in turbine engines. The use of microwave sensors for this application is a new concept. Techniques on calibrating the sensors along with installation effects are not well quantified as they are for other sensor technologies. Developing calibration techniques and evaluating installation effects are essential in using these sensors to make tip clearance and tip timing measurements. As a means of better understanding these issues, the microwave sensors were used on a bench top calibration rig, a large axial vane fan, and a turbofan. Background on the microwave tip clearance sensor, an overview of their calibration, and the results from their use on the axial vane fan and the turbofan will be presented in this paper.
    Keywords: Aircraft Propulsion and Power
    Type: E-16826 , 47th AIAA Aerosciences Conference; Jan 05, 2009 - Jan 08, 2009; Orlando, FL; United States
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