Related Publications
There is much interest in scramjet propulsion for manned and unmanned applications. Early
work focused on hydrogen as the fuel, which has attractive energy per mass properties, but
requires cryogenic storage to keep the fuel volume to acceptable levels. Hydrogen fuel has
short vehicle fuel storage limits and longer refueling times compared to traditional liquid
aviation fuels. For these reasons there is interest in using liquid hydrocarbon fuels more
similar to current aviation fuel. To evaluate current scramjet combustor designs using liquid??
work focused on hydrogen as the fuel, which has attractive energy per mass properties, but
requires cryogenic storage to keep the fuel volume to acceptable levels. Hydrogen fuel has
short vehicle fuel storage limits and longer refueling times compared to traditional liquid
aviation fuels. For these reasons there is interest in using liquid hydrocarbon fuels more
similar to current aviation fuel. To evaluate current scramjet combustor designs using liquid??
: The internal surfaces of liquid hydrocarbon-fueled rocket engine thrust chambers, throats, and nozzles are exposed to high pressure combustion products at temperatures beyond 6000 F. Regenerative cooling is widely used in these engines to prevent overheating of the copper alloy liners. As a result, high heat flux fuel-wetted surfaces reach temper…
The development of a new, robust, portable life support system (PLSS) is currently a crucial need for NASA as it continues making advances in space exploration and extends its missions beyond low Earth orbit. The control of carbon dioxide (CO2) produced by astronauts during extravehicular activities (EVAs) is a critical function of the PLSS. Althou…
Present designs for scramjet-powered hypersonic missiles employ simple rocket boosters to bring them up to minimum operating speeds where a dual-mode ram/scram engine can take over. However, the low air pressures and temperatures and the very short residence times make scramjet ignition at altitude difficult. Various methods to improve ignition and…
In an SBIR Phase I project for AFRL, Reaction Systems completed the conceptual design of a scramjet missile ignition system using stored nitrous oxide for fuel atomization barbotage gas and/or a pilot ignition torch. Exothermically decomposing N2O to N2 and O2 can deliver over 845 kW of thermal power per pound per second of N2O flow to aid the engi…
This work reports the synthesis, characterization and performance of reforming catalysts based upon dispersed Rh clusters on hexaaluminate supports. Two different hexaaluminates were prepared, one with a Ca substitution and one with a strontium substitution. The hexaaluminates are synthesized with a co-precipitation process and the Rh was added via…
TDA Research Inc has identified several additives that block the formation of the metastable carbide intermediates on high alloy metal surfaces during the thermal cracking of n-heptane. Laboratory experiments were conducted to measure the effect of the Se additive on reducing filamentous coke formation in metal tubes. Inconel 625 and Incoloy 800HT…
In February 2004 NASA released “The Vision for Space Exploration.” The goals outlined in this document include extending the human presence in the solar system, culminating in the exploration of Mars. A key requirement for this effort is to identify a safe and effective method to process waste. Methods currently under consideration include incinera…
Hypersonic air-breathing vehicles travel at high speeds and generate heat loads that are greater than can be met from sensible heating of the fuel. However, the fuel can provide about 50% more heat sink capacity if it undergoes endothermic thermal cracking reactions before combustion. Unfortunately, thermal cracking reactions require high temperatu…
This paper reports the results of experimental and modeling efforts to characterize partial oxidation of methane to produce synthesis gas (H2 and CO) using metal-substituted hexaaluminate catalysts in short-contact-time reactors. Hexaaluminate catalysts offer excellent high-temperature stability compared to the equivalent metal-based catalysts. The…
Currently, there is a strong need to develop new weapons systems that incorporate advanced propulsion technologies. However, these systems place severe demands on combustion and thus methods to improve combustion by reducing ignition delay or widening the stable flame conditions are also required. Although a catalyst would allow combustion to begin…
The cost of delivering the payloads to space increases dramatically with distance and therefore missions to deep space place a strong emphasis on reducing launch weight and eliminating resupply requirements. The Vapor Phase Catalytic Ammonia Removal (VPCAR) system, which is being developed for water purification, is an example of this focus because…
The results of a combined experimental and modeling effort to characterize partial oxidation of methane using metal-substituted hexaaluminate catalysts are presented. Robust systems for the production of synthesis gas are developed. The investigation considers two-stage combinations of Ni- and Rh-substituted hexaaluminates. The catalysts are suppor…
This paper reports a quantitative comparison between two metal-substituted hexaaluminate catalysts and supported Pd catalyst (3 wt.% Pd/?-Al2O3). Measured species profiles in stagnation-flow boundary layers are used to infer reaction rates by heterogeneous catalysis. The Pd-substituted material (Sr0.5Pd0.5Al11O18??) is suitable for low-temperature…
Microprobe mass-spectrometric sampling is used to measure major species in a stagnation-point flow over a heated La0.267Sr0.333Mn0.4Al11O18 hexaaluminate catalyst surface. The temperature of the catalytic surface is controlled, and the flow is composed of high-purity methane and air. A chemically-reacting flow model with a global surface-reaction m…
This paper is an experimental and modeling study of catalytic combustion of lean methane/air mixtures in stagnation flow over a strontium-palladium-substituted hexaluminate catalyst surface. It reports gas-phase profiles in the stagnation-flow boundary layer as measured by microprobe mass-spectrometric sampling. A chemically reacting flow model is…
Recently, NASA has increased its emphasis on reducing the cost of reaching low Earth orbit. Studies indicate that using a rocket based combined cycle (RBCC) engine could help achieve significant cost reductions. In the third stage of a RBCC launch, the air-breathing vehicle will travel at speeds from Mach 5 to Mach 10 prior to exiting the atmospher…
Aircraft designed for hypersonic flight must incorporate active cooling in the propulsion system. Hydrocarbon cracking reactions produce a high endotherm; however, without a catalyst these reactions require very high temperatures, which reduces the allowable stress in the heat exchanger materials and increases wall thickness and weight. The goal of…
This contract focuses on the development of sorbents and processes for removal of H{sub 2}S from hot coal gas with the product of sorbent regeneration being elemental sulfur. TDA Research`s process uses a regenerable tin(IV) oxide-based (SnO{sub 2}) sorbent as the first sorbent and zinc ferrite (or zinc titanate) as a second sorbent.
Decomposition of a fuel-soluble precursor was used for in situ generation of Pd/PdO nanoparticles, which then catalyzed ignition of the methane/O 2 /N 2 flow. To help understand the relationship between particle properties and activity, the composition, structure, and surface chemical state of the particles were determined by a combination of high-…
The system is based on the absorption of hydrogen sulfide (H?S) by stannic (tin) oxide. Two sorbents are required, the first sorbent is tin oxide and the second sorbent is a zinc oxide based material (i.e., zinc ferrite or zinc titanate) which is regenerated by air producing SO?. TDA`s process carries out a modified Claus reaction to reduce the SO?…
Hexaaluminate catalysts offer excellent high-temperature stability compared to the equivalent metal-based catalysts. Their stability also lends well to use as a catalyst support. How-ever, use of novel hexaaluminates is limited in fuel processing for fuel-cell applications. In this paper, we report on the per-formance of hexaaluminates as a catalys…