Jennifer Allred’s research while affiliated with Johnson Space Center and other places

Tests were conducted with the RS-18 rocket engine using liquid oxygen (LO2) and liquid methane (LCH4) propellants under simulated altitude conditions at NASA Johnson Space Center White Sands Test Facility (WSTF). This project is part of NASA's Propulsion and Cryogenics Advanced Development (PCAD) project. "Green" propellants, such as LO2/LCH4, offer savings in both performance and safety over equivalently sized hypergolic propulsion systems in spacecraft applications such as ascent engines or service module engines. Altitude simulation was achieved using the WSTF Large Altitude Simulation System, which provided altitude conditions equivalent up to ∼122,000 ft (∼37 km). For specific impulse calculations, engine thrust and propellant mass flow rates were measured. LO2 flow ranged from 5.9 - 9.5 lbm/sec (2.7 - 4.3 kg/sec), and LCH4 flow varied from 3.0 - 4.4 lbm/sec (1.4 - 2.0 kg/sec) during the RS-18 hot-fire test series. Propellant flow rate was measured using a coriolis mass-flow meter and compared with a serial turbine-style flow meter. Results showed a significant performance measurement difference during ignition startup due to two-phase flow effects. Subsequent cold-flow testing demonstrated that the propellant manifolds must be adequately flushed in order for the coriolis flow meters to give accurate data. The coriolis flow meters were later shown to provide accurate steady-state data, but the turbine flow meter data should be used in transient phases of operation. Thrust was measured using three load cells in parallel, which also provides the capability to calculate thrust vector alignment. Ignition was demonstrated using a gaseous oxygen/methane spark torch igniter. Test objectives for the RS-18 project are 1) conduct a shakedown of the test stand for LO2/methane lunar ascent engines, 2) obtain vacuum ignition data for the torch and pyrotechnic igniters, and 3) obtain nozzle kinetics data to anchor two-dimensional kinetics codes. All of these objectives were met with the RS-18 data and additional testing data from subsequent LO2/methane test programs in 2009 which included the first simulated-altitude pyrotechnic ignition demonstration of LO2/ methane.

A ground test article was prepared for RS-18 engine testing using liquid oxygen (LO2) and liquid methane (LCH4) propellants under simulated altitude conditions at NASA Johnson Space Center White Sands Test Facility (WSTF). This project is part of NASA Glenn Research Center's Propulsion and Cryogenics Advanced Development (PCAD) project. "Green" propellants, such as LO2/LCH4, offer savings in both performance and safety over equivalently sized hypergolic propellant systems in lunar vehicle ascent engine applications. LO2/LCH4 testing capability at altitude conditions did not previously exist at WSTF for this size engine, and modifications were made to the Auxiliary Propulsion Systems Test Bed (APSTB) article. Altitude simulation is achieved using the WSTF Large Altitude Simulation System, which provides altitude conditions equivalent to ∼90,000 ft (∼27 km). For specific impulse calculations, engine thrust and propellant mass flow rates are measured. Propellant flow rate is measured using a coriolis-style mass-flow meter, and accuracy is compared with a serial turbine-style flow meter. Thrust is measured using three load cells in parallel. Igniter system capability is being developed to demonstrate two methods, a gaseous oxygen/methane spark torch igniter and solid propellant pyrotechnic igniter. Design, procurement and assembly are complete for the test article and test readiness is expected for hot-fires to begin pending completion of manifold buildup and system checkout. Test objectives for the RS-18 project are 1) conduct a shakedown of the test stand for LO2/LCH4 lunar ascent engines, 2) obtain nozzle kinetics data to anchor two-dimensional kinetics codes, and 3) obtain vacuum ignition data for the torch and pyrotechnic igniters.