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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 289 records · Page 16
All sourcesNASA NTRSDOE OSTI
NASA NTRS2016

Active Flow Control (AFC) and Insect Accretion and Mitigation (IAM) System Design and Integration on the Boeing 757 ecoDemonstrator

This paper presents a systems overview of how the Boeing and NASA team designed, analyzed, fabricated, and integrated the Active Flow Control (AFC) technology and Insect Accretion Mitigation (IAM) systems on the Boeing 757 ecoDemonstrator. The NASA Environmentally Responsible Aviation (ERA) project partnered with Boeing to demonstrate these two technology systems on a specially outfitted Boeing 757 ecoDemonstrator during the spring of 2015. The AFC system demonstrated attenuation of flow separation on a highly deflected rudder and increased the side force generated. This AFC system may enable a smaller vertical tail to provide the control authority needed in the event of an engine failure during takeoff while still operating in a conventional manner over the rest of the flight envelope. The AFC system consisted of ducting to obtain air from the Auxiliary Power Unit (APU), a control valve to modulate the system mass flow, a heat exchanger to lower the APU air temperature, and additional ducting to deliver the air to the AFC actuators located on the vertical tail. The IAM system demonstrated how to mitigate insect residue adhesion on a wing's leading edge. Something as small as insect residue on a leading edge can cause turbulent wedges that interrupt laminar flow, resulting in an increase in drag and fuel use. The IAM system consisted of NASA developed Engineered Surfaces (ES) which were thin aluminum sheet substrate panels with coatings applied to the exterior. These ES were installed on slats 8 and 9 on the right wing of the 757 ecoDemonstrator. They were designed to support panel removal and installation in one crew shift. Each slat accommodated 4 panels. Both the AFC and IAM flight test were the culmination of several years of development and produced valuable data for the advancement of modern aircraft designs.

Alexander, Michael G.↗
NASA NTRS2019

Tribological Performance of PM400 Bushings in Oscillatory Sliding from 25 to 927 °C

Small bore (6.35 millimeter) bushings, made from NASA PM400 solid lubricant composite, were evaluated in oscillatory sliding contact against a nickel-based superalloy shaft. Tests were conducted in air from 25 to 900 degrees Centigrade for extended periods (1 million cycles, plus or minus 15 degrees, 1 hertz) to assess the suitability of PM400 in gas turbine and reciprocating engine exhaust gas path control valve applications. Operating torque and estimated friction was monitored throughout the test duration and wear was measured at the end of test. In general, friction, torque and wear was low. At temperatures above 600 degrees Centigrade, bushing dimensional stability was achieved via short duration pre-test furnace exposure heat treatments. Preliminary test results show that bushings made from NASA PM400 are feasible for aerospace and industrial applications.

high temperature solid lubricants↗
NASA NTRS2018

ISS Columbus Heat Exchanger Close Call Investigation Case Study

During International Space Station (ISS) Expedition 38, just days before Christmas 2013, the External Active Thermal Control System (EATCS) on the ISS Columbus Moderate Temperature Loop (MTL) Interface Heat Exchanger (IFHX) shut down due to low temperatures. Engineers on the ground scrambled for several days to troubleshoot a pump module Flow Control Valve (FCV) problem, however; no one recognized that the core temperature of the Columbus MTL IFHX was continuing to drop, to the point that water in the system could freeze. Freezing could rupture the core, resulting in high pressure ammonia entering the cabin of the ISS. With no way to clean up the ammonia, ISS crew would have to evacuate the U.S. segment of the station. Columbus MTL IFHX rupture is considered a catastrophic failure and could potentially result in a loss of crew/loss of vehicle. How did engineers miss this potentially catastrophic issue?

Joyce B Abbey↗
NASA NTRS2017

Design and Development of the Heat Redistribution System for the Mission to Europa Spacecraft:

This paper details the conceptual design of the Heat Redistribution System (HRS) used for thermal control of the Europa Clipper spacecraft. The solar powered spacecraft will launch in the early 2020s and will study Jupiter’s Icy moon, Europa, where previous investigations have indicated the possibility of a liquid water ocean underneath its ice-encrusted surface. The spacecraft will execute multiple flybys of Europa while relying on the HRS for thermal control of the spacecraft bus. The HRS utilizes a Mechanically Pumped Fluid Loop (MPFL) to reclaim waste heat from an avionics and payload electronics compartment and redistribute it to other parts of the spacecraft, such as the propulsion module structure and the louver-radiator assembly. A “replacement heater block” provides supplemental heat when needed to maintain the spacecraft hardware above its allowable flight temperatures. Additionally, a set of thermal control valves autonomously actuate to reduce the fluid flow through the radiator during cold environment cases. The HRS was used in previous flight projects at JPL such as Mars Science Laboratory, but the uniqueness of the Europa Clipper mission has mandated changes to previous HRS designs; the most significant design drivers and design changes for this iteration of the HRS are discussed.

Bertagne, Christopher↗
NASA NTRS2019

Thermal control technologies for Europa Clipper mission

The Europa Clipper Mission to Europa, a moon of Jupiter, is planned for a launch in 2023. Since Europa is at a large distance (5.6 A.U.) from the Sun, the solar flux is less than 4% of that at Earth. This requires very large solar arrays to meet the power demands of a typical new mission concept. Hence, conservation of power for use in thermal control is extremely important. To achieve this goal a mechanically pumped fluid loop heat rejection system (HRS) is utilized to harvest waste heat from the spacecraft components. In addition to this, several thermal control technologies are employed. They include a high performance dual Multi-Layer Insulation (MLI) blanket design to minimize the large majority of heat loss from the spacecraft; two passive thermal control valves in series to greatly reduce the heat loss from the HRS to its radiator; and a low temperature louver to further reduce the loss from the radiator. This paper will describe these technologies, schemes for their implementation, and results of development tests to validate their performance.

Duran, Mark↗
NASA NTRSDate not supplied

Extravehicular Mobility Unit System-Level Model (SINDA EMU) Usage for Operational Mitigations in Support of US EVA 80

During United States Extravehicular Activity 80 (US EVA 80), water was observed in the helmet of an Extravehicular Mobility Unit (EMU) during cabin repressurization. Through a comparative analysis and Test, Teardown, and Evaluation (TT&E) of this EMU, the most likely cause of the US EVA 80 water failure was determined to be sublimator carryover caused by a comparatively high latent load (water vapor production by the crewmember). High latent load can be reduced by the crewmember adjusting the thermal control valve (TCV) setting on the EMU to prevent the onset of significant sweating. To reduce the risk of high latent load leading to water in the helmet, a potential warning system was developed using the Systems Improved Numerical Differencing Analyzer EMU model (SINDA EMU). The goal of this warning system is to alert the crewmember when they are producing a high latent load and recommend adjustment of the TCV to increase cooling. This warning system was designed to ensure high risk conditions are avoided while simultaneously preventing a system that warns the crewmember too frequently. Theoretical tests of the warning system through modeling calculated that if the warning system were used during US EVA 80, the total latent load could have been reduced by up to 33% which would have significantly reduced the risk of water in the helmet. This analysis also investigated the effectiveness of the warning system on EVAs that occurred after US EVA 80.

Noah Andersen↗
NASA NTRS1984

Motorized Cyrogenic Valve

Remotely-controlled cryogenic valve operates over temperature range from room temperature to 2 K. Valve used in helium dilution refrigerators, cryostats and adiabatic-demagnetization refrigerators.

Salerno, L.↗
NASA NTRS1971

Liquid-fuel valve with precise throttling control

Prototype liquid-fuel valve performs on-off and throttling functions in vacuum without component cold-welding or excessive leakage. Valve design enables simple and rapid disassembly and parts replacement and operates with short working stroke, providing maximum throttling sensitivity commensurate with good control.

Mcdougal, A. R.↗
NASA NTRS2016

Dual Check Valve and Method of Controlling Flow Through the Same

A dual check valve includes, a housing having a cavity fluidically connecting three ports, a movable member movably engaged within the cavity from at least a first position occluding a first port of the three ports, a second position occluding a second port of the three ports, and a third position allowing flow between both the first port, the second port and a third port of the three ports.

Corallo, Roger↗
NASA NTRS1987

Redundant Control for Air-Circulation Valves

Four computers that control airflow to "X-wing" helicopter rotor arranged in redundant configuration. Ensures circulation control of rotor continues to function even if two of computers fail. Rotor uses 48 valve actuators regulating distribution and quantity of air flowing from leading and trailing edges.

Johnson, R., Jr.↗
NASA NTRS1991

Memory Metals (MEMRYSAFE, FIRECHEK, ULTRAVALVE)

A NASA contract led Memry Corporation to the development of commercial products based upon Shape Memory Effect, or the ability of certain metal alloys to change from one shape to another with temperature changes. MEMRYSAFE instantly restricts water flow in shower or sinks before scalding. ULTRAVALVE allows a user to preselect a bathing temperature. FIRECHEK is a fire control safety valve that detects unsafe temperatures and shuts off pneumatic pressure that operates control valves in industrial process lines containing hazardous gases or fluids.

Source record↗
NASA NTRS2003

Shuttle Primary Reaction Control Subsystem Thruster Fuel Valve Pilot Seal Extrusion: A Failure Correlation

Pilot operated valves (POVs) are used to control the flow of hypergolic propellants monomethylhydrazine (fuel) and nitrogen tetroxide (oxidizer) to the Shuttle orbiter Primary Reaction Control Subsystem (PRCS) thrusters. The POV incorporates a two-stage design: a solenoid-actuated pilot stage, which in turn controls a pressure-actuated main stage. Isolation of propellant supply from the thruster chamber is accomplished in part by a captive polytetrafluoroethylene (PTFE) pilot seal retained inside a Custom 455.1 stainless steel cavity. Extrusion of the pilot seal restricts the flow of fuel around the pilot poppet, thus impeding or preventing the main valve stage from opening. It can also prevent the main stage from staying open with adequate force margin, particularly if there is gas in the main stage actuation cavity. During thruster operation on-orbit, fuel valve pilot seal extrusion is commonly indicated by low or erratic chamber pressure or failure of the thruster to fire upon command (Fail-Off). During ground turnaround, pilot seal extrusion is commonly indicated by slow gaseous nitrogen (GN2) main valve opening times (greater than 38 ms) or slow water main valve opening response times (greater than 33 ms). Poppet lift tests and visual inspection can also detect pilot seal extrusion during ground servicing; however, direct metrology on the pilot seat assembly provides the most quantitative and accurate means of identifying extrusion. Minimizing PRCS fuel valve pilot seal extrusion has become an important issue in the effort to improve PRCS reliability and reduce associated life cycle costs.

Waller, Jess↗
NASA NTRS1983

Fuel control for gas turbine with continuous pilot flame

An improved fuel control for a gas turbine engine having a continuous pilot flame and a fuel distribution system including a pump drawing fuel from a source and supplying a line to the main fuel nozzle of the engine, the improvement being a control loop between the pump outlet and the pump inlet to bypass fuel, an electronically controlled throttle valve to restrict flow in the control loop when main nozzle demand exists and to permit substantially unrestricted flow without main nozzle demand, a minimum flow valve in the control loop downstream of the throttle valve to maintain a minimum pressure in the loop ahead of the flow valve, a branch tube from the pilot flame nozzle to the control loop between the throttle valve and the minimum flow valve, an orifice in the branch tube, and a feedback tube from the branch tube downstream of the orifice to the minimum flow valve, the minimum flow valve being operative to maintain a substantially constant pressure differential across the orifice to maintain constant fuel flow to the pilot flame nozzle.

Swick, Robert M.↗