Mechanical & Fluid Systems

'Snap' Design Mimics Venus Flytrap

A team led by physicist Christian Santangelo at the University of Massachusetts Amherst uses curved creases to give thin shells a fast, programmable snapping motion. The technique – inspired by the natural "snapping systems" like Venus flytrap leaves and hummingbird beaks – avoids the need for complicated materials and fabrication methods when creating structures with fast dynamics.

Posted in: News, Materials, Joining & Assembly, Mechanical Components

DC Transformer

This transformer can fill a role in which DC conversion potential, coupled with power filtering/storage capability, is required in high-DC power transmission.

John F. Kennedy Space Center, Florida

A component-level DC transformer was developed in which no alternating currents or voltages are present. It operates by combining features of a homopolar motor and a homopolar generator, both DC devices, such that the output voltage of a DC power supply can be stepped up (or down) with a corresponding step down (or up) in current. The DC transformer should be scalable to low-megawatt levels, but is more suited to high-current than high-voltage applications.

Posted in: Briefs, TSP, Mechanical Components, Electrical systems, Electric power

Wallops Flight Facility 6U Advanced CubeSat Ejector (ACE)

Goddard Space Flight Center, Greenbelt, Maryland

Six-unit (6U) CubeSats are recognized as the next nanosatellite to be considered for standardization. The CubeSat standard established by California Polytechnic University (Cal Poly), which applies to 1U–3U sizes, has proven to be a valuable asset to the community. It has both provided design guidelines to CubeSat developers and a consistent, low-risk interface to launch service providers. This has ultimately led to more flight opportunities for CubeSats. A similar path is desired for the 6U CubeSat. Through this process of standardization, a consistent, low-risk interface for the 6U needs to be established.

Posted in: Briefs, TSP, Mechanical Components, Mechanics, Satellites

Improved Attachment Design for Ceramic Turbine Blades Via Hybrid Concepts

This approach facilitates increased precision and ease of handling the blades during assembly.

John H. Glenn Research Center, Cleveland, Ohio

This innovation is a hybrid metal-ceramic matrix composite (CMC) turbine blade in which a SiC/SiC CMC airfoil section is bonded to a single-crystal superalloy root section in order to mitigate risks associated with an all-CMC blade inserted in a superalloy disk. This will allow current blade attachment technology (SX blade with a dovetail attachment to a slotted Ni disk) to be used with a ceramic airfoil. The bond between the CMC and single crystal will be primarily mechanical in nature, and enhance with clamping arising from thermal expansion mismatch. Two single-crystal root sections will be bonded to each other using diffusion bonding at temperatures near 1,200 °C. The single crystals will form a clamshell around the CMC, with little or no gap between the metal and ceramic. Upon cooling, the metal will shrink around the CMC to firmly clamp it. It is envisioned that this will allow the blade root to operate at temperatures up to about 800 °C. Single crystals will resist stress relaxation at this temperature, thus maintaining clamping loads for long lives. The hybrid concept plus the method of manufacture is new technology.

Posted in: Briefs, TSP, Mechanical Components, Design processes, Ceramics, Composite materials

Powdered Copper Cryogenic Heat Exchanger

This technology provides a high level of thermal performance while dramatically simplifying the chore of determining safety factors.

John F. Kennedy Space Center, Florida

This work involved designing a liquid nitrogen cold-plate heat exchanger with a high thermal mass using code-standard, high-pressure tubing. High thermal mass requires a substantial amount of material, so heat exchangers of this type are usually fabricated from a solid piece of metal (such as copper) with fluid paths machined into the component. However, standard tubing was desired for the fluid path due to its pressure rating and predictability. The key problem was how to embed copper tubing into a larger mass while maintaining good heat transfer properties.

Posted in: Briefs, TSP, Mechanical Components, Thermal management, Copper

Diminutive Assembly for Nanosatellite deploYables (DANY) Miniature Release Mechanism

New deployment mechanism offers improved reliability with minimum space and weight penalty.

Goddard Space Flight Center, Greenbelt, Maryland

CubeSat appendices such as solar panels and antennas often need to be constrained by a release mechanism during launch. These appendices are then deployed once the desired orbit is reached. The usual constraint method used is a combination of an unpredictable/ unreliable fishing line and burning wire. If a proper release mechanism is used, it utilizes a considerable amount of CubeSat internal space, making the internal packaging of the satellite more difficult. These two methods have adverse effects on CubeSat performance.

Posted in: Briefs, TSP, Mechanical Components, Satellites

Quantitative Real-Time Flow Visualization Technique

This technique enables real-time monitoring of pressure fields and flow measurement.

John H. Glenn Research Center, Cleveland, Ohio

There is a need for experimental techniques that have low cost and rapid turnaround. It is also necessary to obtain quantitative information from such a method. Previous methods are either lacking in quantitative information such as dye or smoke injection, or require considerable set-up and cost such as PIV (particle image velocimetry). A method was developed for visualizing the pressure contours for a turbine cascade in real time to enable rapid evaluation of new concepts. A method for quantitative 3D flow visualization also was developed.

Posted in: Briefs, TSP, Mechanical Components, Computational fluid dynamics, Imaging and visualization

Thin-Film Evaporative Cooling for Side-Pumped Lasers

This technology has applications in advanced lidar systems for weather satellites; in welding, cutting, and marking; and in test and measurement.

Langley Research Center, Hampton, Virginia

A highly efficient way to cool solid-state crystal lasers was developed. This thin-film evaporative cooling technique offers higher optical efficiencies and monochromatic quality than traditional conductive cooling techniques. Developed for use in side-pumped 2.0- micron laser systems used in light detection and ranging (lidar) instruments, the thin-film cooling design concept also has broad utility for diode-pumped solid-state laser (DPSSL) systems, especially those with high heat flux or challenging packaging requirements.

Posted in: Briefs, TSP, Mechanical Components, Optics, Thermal management, Cooling

MEMS Micro-Translation Stage with Large Linear Travel Capability

Marshall Space Flight Center, Alabama

A MEMS (microelectromechanical systems) micro-translation stage (MTS) with large linear travel capability was developed that uses capacitive electrostatic forces created by stators arranged linearly on both sides of a channel, and matching rotors on a moveable shuttle for precise movement of the shuttle. The device, which is essentially a linear motor built from silicon base with microfabrication techniques, will be able to rapidly translate across large distances using only three-phase power. The moveable shuttle can be as small as 100 mm and can house a variety of elements including lenses and mirrors. The shuttle can be tailored to travel distances as small as 10 mm and as large as 300 mm, with as little as 10 mm between adjacent shuttle stops.

Posted in: Briefs, Mechanical Components, Optics

Planar and Non-Planar Multi-Bifurcating Stacked Radial Diffusing Valve Cages

This technology is applicable in systems and devices where high-pressure-differential valves are used.

A valve cage consists of a stackable planar structure design with paths that are azimuthally cut out and connected radially. The pattern causes the flow to move azimuthally and impinge on each other when moving to the next path, thereby reducing the fluid momentum and energy that reduces the erosion capability. The maze-like structure is easy to machine with standard machining techniques.

Posted in: Briefs, TSP, Mechanical Components, Mechanics, Parts

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