Propulsion, aircraft

Fuel Aircraft propulsion Aircraft type Ground power Advanced industrial Heavy duty... 

It is well known that the methods of elastic-plastic fracture mechanics provide more realistic models of cracked structures with high toughness compared with the methods of the linear elastic fracture mechanics. Ductile materials are used in structural elements not only in piping systems of power plants but in chemical industry, in aircraft propulsion systems and elsewhere [1-8], Evidently, cracked elements in chemical or power plants pose a serious threat to operation of these stmctures. Therefore, it is extremely important that the crack will not spread unstably through the pipe thickness. 

Li hydroxide is now used in some water-cooled reactors to inhibit corrosion by control of hydrogen ion concentration. Because the thermal-neutron absorption cross sections of the lithium isotopes are Li, 940b, and Li, 0.037 b, it is necessary to use Li contaiiting less than 0.01 percent Li. Li metal, which melts at 180°C, was proposed as coolant for an aircraft-propulsion reactor, because of its low vapor pressure at high temperature and low neutron-absorption cross section. 

In the 75 years since the discovery of nuclear fission, other applications of nuclear power have been considered—for naval propulsion, aircraft propulsion, and for land transportation (automobiles, trucks, and trains). Nuclear power directly applied to land transportation was quickly considered impractical because of the need to shield a nuclear power plant to protect those in or near the vehicle from harmful levels of radiation. The mass of the shielding made the use of such power plants impractical. 

Using UTC ITAPS Approach, Proceedings, Volume 1 Aircraft Propulsion and Subsystems Integration Evaluation, NASA Glenn Research Center, Cleveland, OH. 

Solid Oxide Fuel Cell APU Feasibility Study for a Long Range Commercial Aircraft Using UTC [TAPS Approach, Aircraft Propulsion and Subsystem s Integration Evaluation, vol. I, NASA/CR-2006-214458/VOL1, National Technical Information Service, Springfield, VA. 

R., Carriere, T., Yamanis, J., and Welch, R. (2006) Fuel cell airframe integration study for short-range aircraft aircraft propulsion and subsystem integration evaluation, vol.l, NASA/CR-2006-214457/VOL1, NASA Center for Aerospace Information, Hanover, MD. 

A basic open-cycle gas turbine, as used for aircraft propulsion, has a combustion chamber as the heater , and gases from the turbine are exhausted to the atmosphere without recycling. The compressor is used to raise the pressure of the combustion air. 

There are two fuel cell systems coimected in parallel. The electric motor used as the aircraft propulsion system is an AC brushless external rotor type. It can be operated within a voltage range between 210 and 330 V. If the upper limit of the cell voltage is set to 0.7 V, the total number of cells should be 834. Although MEAs can be customized from an economical perspective, an off-the-shelf product is favored. An MEA with 165 cm, which is commercially available, is adequate for cases 2, 3, and 4 in Table 23.4. The required power during takeoff is also estimated based on operational experience with the aircraft Antares DLR H2 and is believed to be 40 kW. Within the lower voltage limit of the motor, this power can be reached with 960 cells... 

During the normal landing procedure, no electric power is required therefore, the fuel cell system is in idle state. After landing, power is required to maneuver the aircraft to its final parking position. Subsequently, the shutdown process starts by slowly ramping the load back to idle. Then, electric bleeders are engaged to avoid overvoltage. The electric motor for aircraft propulsion is shut off at this point. While the fuel ceU stack is cooled, the reformer must still be operated to avoid anode starvation until the electric bleeders are finally shut off. 

Metallic components used for the construction of energy conversion/producing systems, petrochemical plants and gas turbines for aircraft propulsion are all required to operate... 

An assembly is an integrated set of components and/or subassemblies that comprise a defined part of a subsystem, for example, the pilot s radar display console or the fuel injection assembly of an aircraft propulsion subsystem. An assembly can also be composed of a number of parts, subassemblies, or any combination thereof joined together to perform a specific function and which can be disassembled without destruction of designed use (i.e., they can be reassembled). Typical examples of assemblies are power supplies, memory boards, switching devices, and so on. An assembly would be reflected as a specific level in a system hierarchy. 

Assembly—an integrated set of components and/or subassemblies that comprise a defined part of a subsystem, for example, the pilot s radar display console or the fuel injection assembly of an aircraft propulsion subsystem... 

This work was supported by the Aircraft Propulsion Materials Project, the Office of Naval Research (Dr. Dave Shifter). The FOD work on the Ml SiC/SiC was performed at the NASA Glenn (Cleveland, OH). 

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