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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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At least 253 records · Page 14
All sourcesNASA NTRSDOE OSTI
NASA NTRS2017

Quantifying Pilot Contribution to Flight Safety during Hydraulic Systems Failure

Accident statistics cite the flight crew as a causal factor in over 60% of large transport aircraft fatal accidents. Yet, a well-trained and well-qualified pilot is acknowledged as the critical center point of aircraft systems safety and an integral safety component of the entire commercial aviation system. The latter statement, while generally accepted, cannot be verified because little or no quantitative data exists on how and how many accidents/incidents are averted by crew actions. A joint NASA/FAA high-fidelity motion-base human-in-the-loop test was conducted using a Level D certified Boeing 737-800 simulator to evaluate the pilot's contribution to safety-of-flight during routine air carrier flight operations and in response to aircraft system failures. To quantify the human's contribution, crew complement (two-crew, reduced crew, single pilot) was used as the independent variable in a between-subjects design. This paper details the crew's actions, including decision-making, and responses while dealing with a hydraulic systems leak - one of 6 total non-normal events that were simulated in this experiment.

Kramer, Lynda J.↗
NASA NTRS2018

Two-Speed Rotorcraft Research Transmission Power-Loss Associated with the Lubrication and Hydraulic Rotating Feed-Through Design Feature

An investigation was completed into the power loss associated with a rotating feed-through (RFT) design feature used to transfer lubrication and a hydraulic control signal from the static reference frame to a rotating reference frame in the NASA GRC two-speed transmission tests conducted in the Variable-Speed Drive Test Rig. The RFT feature, not commercially available, was created specifically for this research project and is integral to all two-speed transmission configurations tested, as well as a variant concept design for a geared variable-speed transmission presented at AHS Forum 71 in 2015. The experimental set-up and results from measurements in the isolated rotating-feed-through (RFT) experiments are presented. Results were used in an overall power loss assessment for a scaled conceptual 1,000 horsepower inline concentric two-speed transmission to support a NASA Revolutionary Vertical Lift Technologies (RVLT) Technical Challenge, demonstrating 50% speed change with less than 2% power loss while maintaining current power-to-weight ratios.

Rotorcraft↗
NASA NTRS2018

Two-Speed Rotorcraft Research Transmission Power-Loss Associated with the Lubrication and Hydraulic Rotating Feed-Through Design Feature

An investigation was completed into the power loss associated with a rotating feed-through (RFT) design feature used to transfer lubrication and a hydraulic control signal from the static reference frame to a rotating reference frame in the NASA GRC two-speed transmission tests conducted in the Variable-Speed Drive Test Rig. The RFT feature, not commercially available, was created specifically for this research project and is integral to all two-speed transmission configurations tested, as well as a variant concept design for a geared variable-speed transmission presented at AHS Forum 71 in 2015. The experimental set-up and results from measurements in the isolated rotating-feed-through (RFT) experiments are presented. Results were used in an overall power loss assessment for a scaled conceptual 1,000 horsepower inline concentric two-speed transmission to support a NASA Revolutionary Vertical Lift Technologies (RVLT) Technical Challenge, demonstrating 50% speed change with less than 2% power loss while maintaining current power-to-weight ratios.

Rotorcraft↗
NASA NTRS2018

Two-Speed Rotorcraft Research Transmission Power-Loss Associated with the Lubrication and Hydraulic Rotating Feed-Through Design Feature

An investigation was completed into the power loss associated with a rotating feed-through (RFT) design feature used to transfer lubrication and a hydraulic control signal from the static reference frame to a rotating reference frame in the NASA GRC two-speed transmission tests conducted in the Variable-Speed Drive Test Rig. The RFT feature, not commercially available, was created specifically for this research project and is integral to all two-speed transmission configurations tested, as well as a variant concept design for a geared variable-speed transmission presented at AHS Forum 71 in 2015. The experimental set-up and results from measurements in the isolated rotating-feed-through (RFT) experiments are presented. Results were used in an overall power loss assessment for a scaled conceptual 1,000 horsepower inline concentric two-speed transmission to support a NASA Revolutionary Vertical Lift Technologies (RVLT) Technical Challenge, demonstrating 50% speed change with less than 2% power loss while maintaining current power-to-weight ratios.

Rotorcraft↗
NASA NTRS2018

Prediction of Thermal Protection System Material Permeability and Hydraulic Tortuosity Factor Using Direct Simulation Monte Carlo

Carbon preforms used in Thermal Protection System (TPS) materials are 80 to 90% porous, allowing for boundary layer and pyrolysis gases to flow through the porous regions. The bulk material properties such as permeability and hydraulic tortuosity factor affect the transport of the boundary layer gases. The use of Direct Simulation Monte Carlo along with the Klinkenberg permeability formulation allows us to compute the continuum permeability and Knudsen correction factor for flow in the transition regime. In this work, we have computed the permeability for two types of carbon preforms, namely, Morgan Felt and FiberForm, and assessed the effect of orientation on the permeability. Since both the materials are anisotropic, the permeability was found to depend on orientation, wherein, the materials are more permeable in the in-plane orientation than the through-thickness orientation. The through-thickness orientation was also more tortuous compared to the in-plane material orientation. Compared to Morgan Felt, FiberForm is less permeable, in both, through thickness and in-plane directions.

Jambunathan, Revathi↗
NASA NTRS2021

Hydraulic Jump Dynamics Above Supercell Thunderstorms

The strongest supercell thunderstorms typically feature an above-anvil cirrus plume (AACP), which is a plume of ice and water vapor in the lower stratosphere that occurs downwind of the ambient stratospheric flow in the lee of overshooting deep convection. AACP-origin hydration of the stratosphere has a poorly constrained role in ozone destruction and surface warming. In this study, we use large eddy simulations corroborated by radar observations to understand the physics of AACP generation. We show that the overshooting top of a simulated supercell can act as a topographic obstacle and drive a hydraulic jump downstream at the tropopause, similar to a windstorm moving down the slope of a mountain but without solid topography. Once the jump is established, water vapor injection deep into the stratosphere may exceed 7 tonnes per second.

Gerald M Heymsfield↗