Coil-On-Plug Ignition for Oxygen/Methane Liquid Rocket Engines in Thermal-Vacuum Environments

A coil-on-plug ignition system has been developed and tested for Liquid Oxygen (LOX)/liquid methane (LCH4) rocket engines operating in thermal vacuum conditions. The igniters were developed and tested as part of the Integrated Cryogenic Propulsion Test Article (ICPTA), previously tested as part of the Project Morpheus test vehicle. The ICPTA uses an integrated, pressure-fed, cryogenic LOX/LCH4 propulsion system including a reaction control system (RCS) and a main engine. The ICPTA was tested at NASA Glenn Research Center's Plum Brook Station in the Spacecraft Propulsion Research Facility (B-2) under vacuum and thermal vacuum conditions. A coil-on-plug ignition system has been developed to successfully demonstrate ignition reliability at these conditions while preventing corona discharge issues. The ICPTA uses spark plug ignition for both the main engine igniter and the RCS. The coil-on-plug configuration eliminates the conventional high-voltage spark plug cable by combining the coil and the spark plug into a single component. Prior to ICPTA testing at Plum Brook, component-level reaction control engine (RCE) and main engine igniter testing was conducted at NASA Johnson Space Center (JSC), which demonstrated successful hot-fire ignition using the coil-on-plug from sea-level ambient conditions down to 10(exp -2) torr. Integrated vehicle hot-fire testing at JSC demonstrated electrical and command/data system performance. Lastly, hot-fire testing at Plum Brook demonstrated successful ignitions at simulated altitude conditions at 30 torr and cold thermal-vacuum conditions at 6 torr. The test campaign successfully proved that coil-on-plug technology will enable integrated LOX/LCH4 propulsion systems in future spacecraft

Numerical Investigation Of Impact Of Relative Humidity On Droplet Accumulation And Film Cooling

During the summer, high inlet temperatures affect the power output of gas turbine systems. Evaporative coolers have gained popularity as an inlet cooling method for these systems. Wet compression has been one of the common evaporative cooling methods implemented to increase power output of gas turbine systems due to its simple installation and low cost. This process involves injection of water droplets into the continuous phase of compressor to reduce the temperature of the flow entering the compressor and in turn increase the power output of the whole gas turbine system. This study focused on a single stage rotor-stator compressor model with varying inlet temperature between 300K and 320K, as well as relative humidity between 0% and 100%. The simulations are carried out using the commercial CFD tool ANSYS: FLUENT. The study modeled the interaction between the two phases including mass and heat transfer, given different inlet relative humidity (RH) and temperature conditions. The Reynolds Averaged Navier-Stokes (RANS) equations with k-epsilon turbulence model were applied as well as the droplet coalescence and droplet breakup model considered in the simulation. Sliding mesh theory was implemented to simulate the compressor movement in 2-D. The interaction between the blade and droplets were modeled to address all possible interactions; which include: stick spread, splash, or rebound and compared to an interaction of only reflect. The goal of this study is to quantify the relation between RH, inlet temperature, overall heat transfer coefficient, and the heat transferred from the droplets to the blades surface. The result of this study lead to further proof that wet compression yields higher pressure ratios and lower temperatures in the domain under all of the cases. Additionally, droplet-wall interaction has an interesting effect on the heat transfer coefficient at the compressor blades

Numerical investigation of impact of relative humidity on droplet accumulation and film cooling on compressor blades

During the summer, high inlet temperatures affect the power output of gas turbine systems. Evaporative coolers have gained popularity as an inlet cooling method for these systems. Wet compression has been one of the common evaporative cooling methods implemented to increase power output of gas turbine systems due to its simple installation and low cost. This process involves injection of water droplets into the continuous phase of compressor to reduce the temperature of the flow entering the compressor and in turn increase the power output of the whole gas turbine system. This study focused on a single stage rotor-stator compressor model with varying inlet temperature between 300K and 320K, as well as relative humidity between 0% and 100%. The simulations are carried out using the commercial CFD tool ANSYS: FLUENT. The study modeled the interaction between the two phases including mass and heat transfer, given different inlet relative humidity (RH) and temperature conditions. The Reynolds Averaged Navier-Stokes (RANS) equations with k-epsilon turbulence model were applied as well as the droplet coalescence and droplet breakup model considered in the simulation. Sliding mesh theory was implemented to simulate the compressor movement in 2-D. The interaction between the blade and droplets were modeled to address all possible interactions; which include: stick spread, splash, or rebound and compared to an interaction of only reflect. The goal of this study is to quantify the relation between RH, inlet temperature, overall heat transfer coefficient, and the heat transferred from the droplets to the blades surface. The result of this study lead to further proof that wet compression yields higher pressure ratios and lower temperatures in the domain under all of the cases. Additionally, droplet-wall interaction has an interesting effect on the heat transfer coefficient at the compressor blades

Experimental Study of Thermoelectric Properties of SWCNTs and SiC Nanoparticles and its Composites Doped with Sol-gel

Thermoelectric (TE) properties of Single wall carbon nanotubes (SWCNTs) and Silicon carbide (SiC) nanoparticles after treated with sol-gel dopants at elevated temperature. Different combinations of P and N type sol-gels were used. The combinations were Boron-Antimony, Aluminum-Antimony, Aluminum-Phosphorus and Boron–Phosphorus. The nanoparticles were randomly distributed on a nonconductive glass substrate and hot and cold junctions were created using silver epoxy and Alumel (Ni-Al) wire. The carbon nanotubes used were approximately 60% semiconducting and 40% metallic. Voltage (mV), current (μA) and resistance (Ω) were measured across the distributed nanoparticles within 160° C temperature difference. The Seebeck coefficient for pristine SWCNTs was 0.12 mV/oC. When doped with Boron-Antimony the Seebeck coefficient increased to 0.981 mV/°C. On the hand, SiC nanoparticles showed no TE effect at pristine form, but when infused with SWCNTs substantial TE effect was present. Even though the Seebeck coefficient was in a similar range with different SWCNT concentrations (wt%), current, resistance and Power factor (P.F.) changed with wt% of nanotubes. Resistance of the nanotube samples slightly decreased with the increase in temperature. Finally, the SiC+SWCNT composites were prepared using the sintering process at around 1500° C. Thermoelectric and Mechanical properties of the composites were tested. The structure-property relation was analyzed using SEM (scanning electron microscope) and XRD (X-ray diffraction). It was revealed that fiber like SWCNTs created randomly distributed network with Nano contact junctions inside the SiC matrix and enhance thermoelectric and mechanical properties in the combined SiC+SWCNTs material system

SiC-CNT Multifunctional Nanocomposites for High Temperature Structural, Thermoelectric and Sensing Applications

The purpose of this project is to study the thermal-electrical and mechanical properties of the Nanojunctions between Single-Wall Carbon Nanotubes (SWCNT) and Silicon Carbide (SiC). The mixture was done by spreading the nanoparticles in a solution of ethanol and SiC, then sintered to a solid sample of 10 mm x 10 mm x 35 mm, which was attached with Alumel (Ni-Al) wire using silver epoxy to form a circuit for recording during fracture testing. The carbon nanotubes used were approximately 60% semiconducting and 40% metallic. The themal-electrical effect changed when SWCNTs (at 2, and 5 wt%) were infused into SiC. The change was expected to be produced from the imperfections induced by the fratures. Although the Seebeck coefficient was in a similar range with different SWCNT concentrations and combinations (Boron, SiC nanoparticles), the mechanical properties were expected to change. The resistance also slightly increased with the increase in deformation of the specimen. Finally, the structures created were analyzed in a SEM (scanning electron microscope) and XRD (X-Ray Diffraction) after they had failed. The results show that there were networks created by SWCNTs with Nano junctions (NJ) inside the SiC matrix and enhanced the thermal-electrical and mechanical properties in the combined SiC+SWCNTs composite material