Mechanical & Fluid Systems

Process for Forming a High-Temperature Single Crystal Preloader

Non-contacting, acoustic pressure seals and preloader superalloys prevent fluid leakage.Friction has long been a thorny problem for sealing-device designers. Traditional sealing devices rely on a contacting relationship between surfaces and sealing elements to prevent fluid leakage, but in the case of moving elements, this contact produces friction that causes wearing and eventual failure of the sealing system. Friction also consumes energy and produces harmful debris. In a new breakthrough, however, researchers at NASA’s Glenn Research Center have patented an acoustic seal that generates a pressure barrier to prevent fluid leakage from a high-pressure area. Instead of using contacting components as a seal, the patented seal employs acoustic technology to generate pressure waves that control, mitigate, or prevent fluid leakage. The result is a very low-leakage, non-contact seal that eliminates problems associated with friction. In addition, when traditional seals are needed in extremely high-temperature environments, Glenn innovators have developed new processes to enable the fabrication of single-crystal superalloys that can increase the upper limit of thermal seals to greater than 2000 °F.

Posted in: Briefs, Mechanical Components, Mechanics, Fluid Handling

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Compact Vibration Damper

Applications include wind tunnel models, launch vehicles, smokestacks, helicopters, wind turbines, and skyscrapers.NASA’s Langley Research Center has developed a compact tuned damper to reduce vibration occurring at a fixed frequency. Tuned dampers reduce vibration of the base structure by the dissipation of energy. The magnitude of the dissipated energy is proportional to the square of the displacement or velocity of the tuned mass, which in turn is proportional to the range of motion. The NASA damper design allows the slider mass to achieve 2× to 3× greater range of motion than that found in conventional devices. This enables 4× to 9× more effectiveness for the same size and weight; or the same effectiveness for a 4× to 9× decrease in weight. The damper is also tunable and can be adjusted in effectiveness. The damper can be made small enough for use in wind tunnel tests, or scaled up to large sizes like those used in helicopters, wind turbines, or skyscrapers.

Posted in: Briefs, Mechanical Components, Mechanics

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Fluidic Oscillator Array for Synchronized Oscillating Jet Generation

This technology can be used in aerospace applications, shipbuilding, gas turbines, and commercial spa equipment.NASA’s Langley Research Center develops innovative technologies to control fluid flow in ways that will ultimately result in improved performance and fuel efficiency. Often called fluidic oscillators, sweeping jet actuators, or flip flop oscillators, these flow-control devices work based on the Coanda effect. They can be embedded directly into a control surface (such as a wing or a turbine blade) and generate spatially oscillating bursts (or jets) of fluid to improve flow characteristics by enhancing lift, reducing drag, or enhancing heat transfer. Recent studies show up to a 60% performance enhancement with oscillators. NASA offers two new fluidic oscillator designs that address two key limitations of these oscillators: coupled frequency-amplitude and random oscillations. One oscillator effectively decouples the oscillation frequency from the amplitude. The other design enables synchronization of an entire array. The new oscillators have no moving parts — oscillation, decoupling, and synchronization are achieved entirely via internal flow dynamics.

Posted in: Briefs, Mechanical Components, Mechanics, Fluid Handling

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Conduit Purging Device and Method

Applications include pneumatic or hydraulic tubing, high-purity gas processing, brake lines, automobiles, and aircraft.NASA’s Goddard Space Flight Center invites companies to license this dead-end welding device for use in the welding of tubing. This technology solves the problem of unacceptable welds in dead-end configurations. The technique has been proven to be highly successful with many dead-end weld configurations, as well as with various alloys. It produces a consistently higher-quality dead-end weld than conventional welding techniques, and does so in a fraction of the time. Its monitoring capability enables precision control in any deadend configuration. It is a reliable and very low-maintenance device that presents no safety concerns.

Posted in: Briefs, Mechanical Components, Mechanics

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Multi-Spoked Wheel Assembly

This innovation can be applied to robots used by first responders and others as a single ground-traction mechanism in a variety of environments. NASA Glenn researchers have developed a spoked drive mechanism for robots and other vehicles that is capable of two rotational modes. This robust ground traction (drive) assembly for remotely controlled vehicles operates smoothly not only on surfaces that are flat, but also upon surfaces that include rugged terrain, snow, mud, and sand. The assembly includes a sun gear and a braking gear. The sun gear is configured to cause rotational force to be applied to second planetary gears through a coupling of first planetary gears. The braking gear is configured to cause the assembly (or the second planetary gears) to rotate around the braking gear when an obstacle or braking force is applied.

Posted in: Briefs, Mechanical Components

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Nanotube-Based Device Cooling System

Carbon nanotubes (CNTs) are being studied for applications in high-strength/low-weight composites and other applications. Recent research on thermal dissipation materials for high-power electronic devices is generating a lot of interest in various industries. NASA has developed a method for cooling a device, such as an electronic device, that produces extreme heat that must be dissipated. CNTs have attracted much attention due to their extraordinary mechanical and unique electronic properties. Computer chips have been subjected to higher and higher thermal loads and it is challenging to find new ways to perform heat dissipation. As a result, heat dissipation demand for computer systems is increasing dramatically. CNTs, which are known to provide high thermal conductivity and to be small and flexible, are suitable for cooling these electronic devices. One critical problem is provision of a compliant, usable composite of CNTs with a material that meets other needs for heat dissipation.

Posted in: Briefs, Mechanical Components

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A Method for Accurate Load/Position Control of Rigidly Coupled Electromechanical Actuators

NASA has developed a technique designed to prevent cross-coupling in systems where two or more linear electro-mechanical actuators (EMA) are rigidly connected and are in danger of becoming cross-coupled. In such systems where the linked EMAs are commanded to achieve two distinct goals, such as position and load control, control problems often arise — especially at higher load and linear velocity levels. Both position and load control become inaccurate and in certain situations, stability of the overall system may be compromised. The NASA-developed approach mitigates the problem and achieves both accurate position following and desired load levels between the two (or more) actuators.

Posted in: Briefs, Mechanical Components, Mechanics, Positioning Equipment

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