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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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116 records · Page 7
All sourcesNASA NTRSDOE OSTI
NASA NTRS1995

STRV-1B Cryocooler Vibration Suppression

The STRV-1B cryocooler vibration suppression experiment is a satellite flight demonstration of piezo vibration-suppression technology. A very small, tactical stirling-cooler was flown primarily as a vibration source. Two types of piezo actuators were demonstrated. Low-voltage piezo translators were used to move the entire cryocooler so that the tip of the coldfinger stood still. Also, high-voltage ceramic applique was bonded to the base of the coldfinger providing a second actuation method to compare with the translators. three eddy current transducers were used to measure the coldfinger tip motion relative to the experiment case. The eddy current signal drove two types of control systems. A digital adaptive-feed- forward control system was used to cancel the tip motion of the cryocooler in three dimensions. An analog-comb filter controller was also developed to contrast the two techniques. Motion suppression does nothing to suppress the unbalanced forces in the cryocooler, so a triaxial accelerometer measured the vibration of the satellite in response to the cryocooler. Satellite/ground test results from each of the experiment systems are shown and the systems are compared.

STRV-1B↗
NASA NTRS2021

Single-Event Effect Test Report Texas Instruments DS25BR100 LVDS Buffer

This study was to determine the destructive single-event effect (SEE) susceptibility of the DS25BR100 series Low-Voltage Differential Signaling (LVDS) Buffers with Pre-emphasis and Equalization (DS25BR100, 110, and 120). The device was monitored primarily for destructive events while exposing it to a heavy ion beam at the Texas A&M University’s (TAMU) K500 Cyclotron.

Ted Wilcox↗
NASA NTRS2022

Novel Processing, Testing and Characterization of Copper/Carbon Nanotube (Cu/CNT) Yarn Composite Conductor

Sustainable electrified aircraft propulsion (EAP) is likely to lead to an increase in the electrical wiring contained within a single aircraft. Since the electrical resistance and mass of copper (Cu) conductors are associated with power losses, it is desirable to design high-conductivity lightweight conductor materials, thus reducing the mass of components like motor windings, low-voltage signal cables, and transmission cables for data and power to improve the overall energy efficiency. This paper describes a unique framework for manufacturing metalized carbon nanotube (CNT) composite conductors, measuring their electrical conductivity and strength, and modeling the overall conductivity and current sharing within such composites. Tensile testing was conducted on the processed composite conductor cables with the use of acoustic emission and electrical resistivity to determine stress-dependent-failure mechanisms while monitoring the electrical conductivity. The average of measured electrical conductivities of annealed Cu/CNT samples from batch 5 was greater than theoretical predictions by 9.8 percent and was also greater than the conductivity of pure annealed Cu by 4.8 percent and had comparable ultimate tensile strengths. Additionally, those Cu/CNT samples provide a 13.5% weight saving over current state of the art copper wires. Theories explaining improved intrinsic conductivity are discussed.

Metalized CNT↗
NASA NTRSDate not supplied

Evaluation of Silicon Carbide Pressure Sensor in Turbofan Engine Core Exhaust Nozzle

We report the results of the evaluation of single crystal 4H-silicon carbide piezoresistive pressure sensors that were directly inserted at the compressor and core exhaust nozzle exits, in shear contact with the engine-internal flow streams of the NASA DGEN Aeropropulsion Research Turbofan, where the operating temperatures at maximum power were ~230 oC, and ~460 oC, respectively. In addition to demonstrating sensor survivability during this maiden test, the frequency responses of the silicon-carbide sensors at the core-nozzle exit were compared against industry-standard silicon-based piezoresistive pressure transducers that externally placed, using an infinite-tube-probe arrangement. The low-voltage output of these early-development SiC sensors limited the frequency range with an acceptable signal-to-noise-ratio for the current application to less than about 2,500 Hz. The low output of the SiC sensors were due to a conservative burst-pressure diaphragm design that can be optimized to increase the frequency range. The results from this initial campaign offered insights to aspects of the sensor that would require further improvement, with the goal of achieving full-bandwidth capture of engine unsteady pressure fluctuations by direct interrogation of the flow field in hostile-environment engine-core components.

Silicon Carbide↗
NASA NTRSDate not supplied

Evaluation of SiC Pressure Sensors in Turbofan Engine Core Exhaust Nozzle

We report the results of the evaluation of single crystal 4H-silicon carbide piezoresistive pressure sensors that were directly inserted at the compressor and core exhaust nozzle exits, in shear contact with the engine-internal flow streams of the NASA DGEN Aeropropulsion Research Turbofan, where the operating temperatures at maximum power were ~230°C, and ~460°C, respectively. In addition to demonstrating sensor survivability during this maiden test, the frequency responses of the silicon-carbide sensors at the core-nozzle exit were compared against industry-standard silicon-based piezoresistive pressure transducers that externally placed, using an infinite-tube-probe arrangement. The low-voltage output of these early-development SiC sensors limited the frequency range with an acceptable signal-to-noise-ratio for the current application to less than about 2,500 Hz. The low output of the SiC sensors were due to a conservative burst-pressure diaphragm design that can be optimized to increase the frequency range. The results from this initial campaign offered insights to aspects of the sensor that would require further improvement, with the goal of achieving full-bandwidth capture of engine unsteady pressure fluctuations by direct interrogation of the flow field in hostile-environment engine-core components.

Silicon Carbide↗
NASA NTRSDate not supplied

Cruise Propulsion System Thermal Analysis for NASA’s X-57 “Maxwell” Mod II Configuration

The X-57 “Maxwell” is NASA’s flight demonstrator for distributed electric propulsion technologies. The X-57 Mod II configuration is designed to test the electric cruise propulsion system for X-57 and features an electric cruise motor mounted in an integral nacelle on each wing. The electric motors and associated control equipment for X-57 Mod II are air-cooled; therefore, they require adequate cooling airflow to stay within temperature limits in all relevant flight conditions within the operational ambient temperature limits set by the X-57 project. A computational flow analysis was conducted to estimate the internal flow properties of the X-57 Mod II cruise nacelles in three critical flight conditions. These flow properties were then used to determine the boundary conditions for individual component thermal models, which were used to estimate individual component operating temperatures. The results indicated that the low-speed, low-altitude initial takeoff climb during hot day conditions was the sizing condition from a cooling perspective. The analysis found that the cooling flowpaths in the X-57 Mod II cruise nacelles are adequate to provide cooling to all components with the appropriate amount of thermal margin except two of the low-voltage control boards in the cruise motor controller. These components would violate required thermal margins by less than two degrees Celsius in the Project Hot Day reference atmosphere.

Nicholas K Borer↗