A review on hydrogen industrial aerospace applications

A summary of performance and lifetime characteristics of pulsed and steady-state magnetoplasmadynamic (MPD) thrusters is presented. The technical focus is on cargo vehicle propulsion for exploration-class missions to the moon and Mars. Relatively high MPD thruster efficiencies of 0.43 and 0.69 have been reported at about 5000-s specific impulse using hydrogen and lithium, respectively. Efficiencies of 0.10 to 0.35 in the 1000to 4500-s specific impulse range have been obtained with other propellants (e.g., Ar, NHa, NI). Electrode power losses of less than 20% at megawatt power levels using pulsed thrusters indicate the potential of high MPD thruster performance. Extended tests of pulsed and steady-state MPD thrusters yield total impulses at least two to three orders of magnitude below that necessary for cargo vehicle propulsion. Performance tests and diagnostics for life-limiting mechanisms of megawatt-class thrusters will require high-fidelity test stands, which handle in excess of 10 kA, and a vacuum facility whose operational pressure is less than 4 x 10 ~ Pa.

Performance and lifetime assessment of magnetoplasmadynamic arc thruster technology

Advances in fuel cell technology have brought about their consideration as sources of power for aircraft. This power can be utilized to run aircraft systems or even provide propulsion power. One of the key obstacles to utilizing fuel cells on aircraft is the storage of hydrogen. An overview of the potential methods of hydrogen storage was compiled. This overview identifies various methods of hydrogen storage and points out their advantages and disadvantages relative to aircraft applications. Minimizing weight and volume are the key aspects to storing hydrogen within an aircraft. An analysis was performed to show how changes in certain parameters of a given storage system affect its mass and volume.

Hydrogen Storage for Aircraft Applications Overview

A summary of performance and lifetime characteristics of pulsed and steady-state magnetoplasmadynamic (MPD) thrusters is presented. The technical focus is on cargo vehicle propulsion for exploration-class missions to the Moon and Mars. Relatively high MPD thruster efficiencies of 0.43 and 0.69 have been reported at about 5000 s specific impulse using hydrogen and lithium, respectively. Efficiencies of 0.10 to 0.35 in the 1000 to 4500 s specific impulse range have been obtained with other propellants (e.g., Ar, NH3, N2). Thermal efficiency data in excess of 0.80 at MW power levels using pulsed thrusters indicate the potential of high MPD thruster performance. Extended tests of pulsed and steady-state MPD thrusters yield total impulses at least two to three orders of magnitude below that necessary for cargo vehicle propulsion. Performance tests and diagnostics for life-limiting mechanisms of megawatt-class thrusters will require high fidelity test stands which handle in excess of 10 kA and a vacuum facility whose operational pressure is less than 3 x 10 to the -4 torr.

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Performance and lifetime assessment of MPD arc thruster technology

High-performance electrothermal thrusters operate in a low nozzle-throat Reynolds number regime. Under these conditions, the flow boundary layer occupies a large volume inside the nozzle, contributing to large viscous losses. Four nozzles (conical, bell, trumpet, and modified trumpet) and a sharp-edged orifice were evaluated over a Reynolds number range of 500 to 9000 with unheated nitrogen and hydrogen. The nozzles showed significant decreases in specific impulse efficiency with decreasing Reynolds number. At Reynolds numbers less than 1000, all four nozzles were probably filled with a large boundary layer. The discharge coefficient decreased with Reynolds number in the same manner as the specific impulse efficiency. The bell and modified trumpet nozzles had discharge coefficients 4 to 8 percent higher than those of the cone or trumpet nozzles. The Two-Dimensional Kinetics (TDK) nozzle analysis computer program was used to predict nozzle performance. The results were then compared to the experimental results in order to determine the accuracy of the program within this flow regime.

https://ntrs.nasa.gov/api/citations/19870010950/downloads/19870010950.pdf

Experimental study of low Reynolds number nozzles

Tests were conducted to investigate the effect of vacuum facility pressure on the performance of small thruster nozzles. Thrust measurements of two converging-diverging nozzles with an area ratio of 140 and an orifice plate flowing unheated nitrogen and hydrogen were taken over a wide range of vacuum facility pressures and nozzle throat Reynolds numbers. In the Reynolds number range of 2200 to 12 000 there was no discernable viscous effect on thrust below an ambient to total pressure ratio of 1000. In nearly all cases, flow separation occurred at a pressure ratio of about 1000. This was the upper limit for obtaining an accurate thrust measurement for a conical nozzle with an area ratio of 140.

/pdf/vacuum-chamber-pressure-effects-on-thrust-measurements-of-43fzsrfpib.pdf

Vacuum chamber pressure effects on thrust measurements of low Reynolds number nozzles

The NASP program is giving us the opportunity to reach new unique answers in a number of engineering categories. The answers are considered “enhancing technology” or “enabling technology”. Airframe materials and densified propellants are examples of “enabling” technology.

/pdf/slush-hydrogen-slh2-technology-development-for-application-3m5dm7xltb.pdf

Slush Hydrogen (SLH2) Technology Development for Application to the National Aerospace Plane (NASP)

Slush hydrogen, a mixture of solid and liquid hydrogen, offers advantages of higher density (16 percent) and higher heat capacity (18 percent) than normal boiling point hydrogen. The combination of increased density and heat capacity of slush hydrogen provided a potential to decrease the gross takeoff weight of the National Aero-Space Plane (NASP) and therefore slush hydrogen was selected as the propellant. However, no large-scale data was available on the production, transfer and tank pressure control characteristics required to use slush hydrogen as a fuel. Extensive testing has been performed at the NASA Lewis Research Center K-Site and Small Scale Hydrogen Test Facility between 1990 and the present to provide a database for the use of slush hydrogen. This paper summarizes the results of this testing.

/pdf/a-summary-of-the-slush-hydrogen-technology-program-for-the-2zy1kxmksi.pdf

A Summary of the Slush Hydrogen Technology Program for the National Aero-Space Plane

Tests were conducted to investigate the effect of vacuum facility pressure on the performance of small thruster nozzles. Thrust measurements of two converging-diverging nozzles with an area ratio of 140 and an orifice plate flowing unheated nitrogen and hydrogen were taken over a wide range of vacuum facility pressures and nozzle throat Reynolds numbers. In the Reynolds number range of 2200 to 12,000 there was no discernable viscous effect on thrust below an ambient to total pressure ratio of 1000. In nearly all cases, flow separation occurred at a pressure ratio of about 1000. This was the upper limit for obtaining an accurate thrust measurement for a conical nozzle with an area ratio of 140.

/pdf/vacuum-chamber-pressure-effects-on-thrust-measurements-of-3snop8hy2k.pdf

Slush hydrogen and triple-point hydrogen offer the potential for reducing the size and weight of future space vehicles because these fluids have greater densities than normal-boiling-point liquid hydrogen In addition, these fluids have greater heat capacities, which make them attractive fuels for such applications as the National Aerospace Plane and cryogenic depots Some of the benefits of using slush hydrogen and triple-point hydrogen for space missions are quantified Some of the major issues associated with using these densified cryogenic fuels for space applications are examined, and the technology efforts that have been made to address many of these issues are summarized

/pdf/technology-issues-associated-with-using-densified-hydrogen-1g3ppk2xi4.pdf

Margaret V. Whalen

Papers

Vacuum chamber pressure effects on thrust measurements of low Reynolds number nozzles

Slush Hydrogen (SLH2) Technology Development for Application to the National Aerospace Plane (NASP)

A Summary of the Slush Hydrogen Technology Program for the National Aero-Space Plane

Vacuum chamber pressure effects on thrust measurements of low Reynolds number nozzles

Technology issues associated with using densified hydrogen for space vehicles