Premixed, High-Pressure, Multi-Fuel Burner

In conjunction with academia and industry, NASA's Glenn Research Center has developed a range of microelectromechanical systems (MEMS)-based and Silicon Carbide (SiC)-based microsensor technologies that are well-suited for many applications. The suite of technologies includes hydrogen and hydrocarbon leak detection sensors; emissions sensor arrays; and high-temperature contact pads for wire bond connections. Currently used to protect astronauts on the International Space Station, the hydrogen and leak detection sensors have many Earth-based applications as well. They can function as a single-sensor unit or as part of a complete smart sensor system that includes multiple sensors, signal conditioning, power, and telemetry. The system can comprise sensors for hydrogen, hydrocarbons, oxygen, temperature, and pressure. The emissions sensor array features a gas-sensing structure that detects various combustion emission species (carbon monoxide, carbon dioxide, oxygen, hydrocarbons, and nitrogen oxides) over a wide range of concentrations. In addition, the emissions sensor array remains highly sensitive and stable while providing gas detection at temperatures ranging from 450 to 600°C. These new sensors provide a combination of responsiveness and durability that offers great value for a wide range of applications and industries.

Traditional fire testing methods often require large samples, open flames, or complicated setups to study combustion. This technology introduces a compact, precise method using a Microscale Fire Calorimeter (MFC) that mimics realistic fire conditions with unprecedented control. When a solid material is thermally decomposed (pyrolyzed), it emits gaseous byproducts. These gases are then premixed with oxygen and combusted in the MFC’s reaction zone at high temperatures, without a visible flame. The MFC system precisely regulates oxygen availability, simulating different fire stages such as over-ventilated (oxygen-rich) and under-ventilated (oxygen-poor) conditions. This allows researchers to analyze how combustion chemistry changes as fires become more intense or oxygen-deprived. The system captures and quantifies the resulting gases and soot, enabling evaluation of environmental pollutants and toxic species produced during each combustion phase. This approach supports safer, smaller-scale laboratory testing while providing valuable data for applications such as material development, regulatory compliance, and forensic analysis. It bridges the gap between benchtop research and real-world fire scenarios.

For extremely high-temperature sealing applications, Glenn researchers have devised novel methods for fabricating single-crystal preloaders. NASA's high-temperature preloaders consist of investment cast or machined parts that are fabricated in various configurations from single crystal superalloys. Machined preloaders include a variety of spring configurations, compressed axially or radially, fabricated from single crystal slabs. Before machining, the slabs are carefully oriented in a special goniometer using x-diffraction techniques. This helps to maintain proper crystal orientation relative to the machined part and the applied loads. For more complex geometry components which cannot be easily and economically machined, an investment casting approach would be used. Complex preloader geometries include wire coil springs of various configurations. These single crystal preloaders would be designed with the appropriate stiffness for the intended thermal barrier/seal application and placed underneath, or integrated within, the seal/barrier. At extrememly high temperature, the preload device keeps the seal/barrier mated against the opposing surface as the gap between the two surfaces changes, maintaining contact between surfaces and preventing convective heat transfer.

Spark-ignition devices have proven to be a high-reliability option for LOX/LCH4 ignition during development of the Integrated Cryogenic Propulsion Test Article (ICPTA) main and reaction control engines (RCEs); however, issues including spark plug durability (ceramic cracking) and corona discharge during simulated altitude testing have been observed, contributing to degraded spark output and no-light engine-start conditions. Innovators discovered that ignition system reliability could be improved and weight reduced by eliminating the traditional coil and spark plug wire. To achieve this result, engineers made the innovation by modifying an automotive coil-on-plug igniter to provide new high sparking energies at the point of combustion using low supply voltages. The coil was modified by vacuum-potting it into a threaded interface that mounts into existing spark plug ports on the ICPTA main engine and the RCEs. Engineers fabricated custom electrode tips that were thread-mounted into the potted coil body. Epoxy insulation was chosen with high dielectric strength to maintain insulation between the electrode and threaded adapter. Vacuum potting successfully prevented pressure or vacuum leakage into the coil body and maintained spark energy and location at the electrode tip. Successful hot-fire ignition was observed at sea-level, altitude, and thermal-vacuum for both ICPTA RCE and main engine igniters down to 10^-3 torr, which approaches the vacuum of cislunar space. This technology is at technology readiness level (TRL) 7 (system prototype demonstration in an operational environment), and the related patent is now available to license. Please note that NASA does not manufacture products itself for commercial sale.

Aircraft thermal management systems typically comprise over half the mass associated with full electric power propulsion systems, with significant negative impact on fuel efficiency. In addition, the traditional method of using jet fuel to cool aircraft generators does not provide enough cooling for use in flight-weight cryogenic systems. Lastly, the much higher bus voltages required for flight-weight systems (4.5 kV vs. 270 V) introduce additional spark-ignition hazards associated with alternative cryogenic cooling fuels, including liquid methane or liquid hydrogen. The Glenn flight-weight thermal management system addresses all of these problems by using the considerable waste heat energy from turbogenerators to create a pressure wave thermoacoustically. This wave can then be delivered quietly and efficiently via routed ductwork to hollow pulse-tube coolers located near any component in the aircraft that requires cooling. The tubes can be fabricated in any length and can be curved to fit any space. This technology also allows waste heat energy to be used in at least four ways: 1) the waste heat energy can drive a thermoacoustics-based ambient or cryogenic heat pump; 2) it can be channeled directly into a thermoacoustic engine that generates power; 3) it can convectively preheat the fuel/ or air supplied to the aircraft engine; 4) it can drive a pulse-tube generator providing power. The delivered thermoacoustic power can provide cabin cooling as well as ambient/cryogenic cooling of converter, cables, and motors. In addition, this power can be converted to local electric power through the use of a transducer (such as a linear alternator) or piezoelectrics. Further, the efficient thermal management system enables the size, mass, and resultant cost of the radiating fins to be reduced. Glenn's system offers an efficient method of cooling next-generation flight-weight electric aircraft with significant benefits for fuel efficiency and safety.