Fast-Acting, Deep-Throttling Hybrid Motor

The Miniature Separable Fill & Drain Valve consists of two halves (ground and flight). The flight half is attached to the vehicle (i.e., CubeSat), and the ground half can be inserted into the vehicle in the same port as the flight half, connecting the two halves together. In normal state, the flight half seals the flow path. When the ground half is connected, the flow path is opened, allowing connected ground support equipment to supply fluid through the valve. The valve is manually operated. There are redundant seals to eliminate leakage around the valve, including NASA's previously-patented Low-Cost, Long Lasting Valve Seal design (Patent No. 10,197,165; see MFS-TOPS-71 in the Links section of this flyer for more information) on the flight half. This eliminates the need for a swaged assembly process and the additional hardware and equipment that are typically required in conventional, elastomeric valve seat installations. The design also includes a cap for the flight half to ensure there is no leakage in flight configuration. The Miniature Separable Fill & Drain Valve has been prototyped and provides valuable benefits for CubeSat applications. The valve could also have applications in the industrial processing industry where low flow devices are commonly used. The design is also scalable to larger applications where the removal of the actuation device would be desired.

Electrically driven turbine engine compressor and propulsion fans require a large stability margin against stall conditions to avoid unwanted performance issues while undergoing transients in operating conditions. This stability margin, while it maintains safe operation, also necessarily reduces the engine performance. Despite extensive research efforts, no viable alternative methods for reducing the operable stability margin and improving engine performance exist. This current innovation, originally conceived for stall prevention, offers a solution by utilizing a supercapacitor in line with an electric motor and motor controller to rapidly change a compressor or propulsor fan speed. The use of the supercapacitor enables rapid extraction, or addition of power, to prevent the fan from stalling. Additionally, this novel drive motor may be used for sensing stall event precursor signals by using the motor controller to detect variations in torque on the shaft caused by variance in loading on the blade system. The improved stall avoidance capabilities allow an engine fan to operate more efficiently, providing more thrust for a given frontal area, increasing operational range, reduced weight, and improved operational safety. The related patent is now available to license. Please note that NASA does not manufacture products itself for commercial sale.

The Precision Low Speed Motor Controller was designed as part of an OpTIIX telescope for the International Space Station. This technology is based on a precise current control loop and a high fidelity velocity measurement algorithm. The precise current loop uses a mathematical model of the electrical dynamics of the motor, custom electronics, and a PI controller to maintain a rapid response and smooth current control. The velocity measurement algorithm is embedded in the velocity loop that is wrapped around the current loop to provide a smooth low velocity control. Current motors are only capable of operating at approximately 15 rpm with a risk of excessive jitters. This technology reduces the responsive rpms by several orders of magnitude to approximately 0.025 rpms. This technology's capability has been integral to the success of several NASA projects, such as the OpTIIX telescope, the NASA Robonaut 2 robot , and the Modular Robotic Vehicle (MRV).

NASAs High Propellant Throughput Small Spacecraft Electric Propulsion thruster offers a propellant throughput capability of greater than 120 kg with a nominal thruster efficiency greater than 50%. The new thruster design combines heritage Hall thruster component design approaches with recent NASA GRC advancements in the areas of advanced magnetic circuit design, robust propellant manifolds, and center mounted cathodes. Prototypes of the High Propellant Throughput Small Spacecraft Electric Propulsion thruster have been fabricated and proof-of-concept has been demonstrated. A significant advancement in the High Propellant Throughput Small Spacecraft Electric Propulsion thruster is NASA's optimized magnetically shielded (OMS) field topology. The new OMS configuration reduces discharge channel erosion rates compared to conventional Hall thrusters, while reducing front pole cover erosion rates compared to traditional magnetically shielded Hall thrusters. This system also includes a largely unibody structure to reduce fabrication cost, increase strength, and optimize thermal management. A coupling plate between the high voltage discharge channel and low voltage thruster body allows more efficient thruster assembly and verification processes. Other design advancements further simplify assembly, improve robustness, and optimize performance.

Vibration problems, which occur more frequently in high power to weight machines, often lead to costly down time, subsequent redesign, and, in some instances, catastrophic failure. A disproportionate number of vibration problems in rotating machinery can be attributed to highly pre-swirled fluid entering tight clearance locations such as seals and fluid bearings. The relationship between high fluid pre-swirl and undesirable vibration issues is clear. Machines with high levels of fluid pre-swirl are more susceptible to instabilities and vibration problems. A top priority in rotor dynamic design, therefore, is to develop devices to minimize the level of fluid pre-swirl entering tight clearance locations. The RVR was designed to condition the flow prior to entering the seal (or axial flow fluid-film bearing) so that the flow through the annular clearance is at a minimum purely axial. While conventional swirl brakes have only been shown to reduce pre-swirl by up to 30%, the RVR can actually reverse the direction of the swirl, so that circumferential fluid velocity flows in a direction counter to shaft rotation. Thus, a classic detriment to rotating machinery has now become an asset to ameliorate vibration issues through the RVR. The RVR is axially efficient, typically increasing the axial length of a smooth annular seal on the order of 10-12%. The RVR has been extensively tested and is now in use at NASA.