Showing papers on "Arcjet rocket published in 2014"

Multidimensional Modeling of Pyrolysis Gas Transport Inside Charring Ablative Materials

Abstract: The behavior of pyrolysis gas transport in arcjet test samples is numerically studied. The simulation of the pyrolysis gas flow inside a porous material is presented, using two different geometries...

Development of the Mars Science Laboratory Heatshield Thermal Protection System

Abstract: Early in the development of the Mars Science Laboratory thermal protection system on the heatshield, project management planned to use Lockheed Martin’s Super Light Ablator in honeycomb as the ablative material based on successful use on previous Mars entry heatshields and on stagnation arcjet tests at heating rates beyond the design levels. Because this heatshield would be the first to experience combined turbulent flow and high shear environments as it entered the Mars atmosphere, tests were performed in various arcjet facilities on flat-plate, wedge, and swept-cylinder specimen configurations in order to ascertain the effects of shear on the material. During the course of these tests, a set of conditions within the flight envelope was identified that resulted in catastrophic failure in the SLA-561V. Consequently, project management decided to replace the SLA-561V with the phenolic-impregnated carbon ablator, the material that had flown successfully on the Stardust mission and was undergoing intense tes...

Arcjet Testing in Shear Environment for Mars Science Laboratory Thermal Protection System

Abstract: Thermal protection system materials for the Mars Science Laboratory mission were tested in the NASA Ames 60 MW arcjet in a shear environment. Shear tests were performed on candidate ablative heat shield materials in wedge and swept cylinder test fixtures. In portions of the expected flight environment, the proposed main heat shield material, known as SLA-561V, recessed orders of magnitude faster than predicted. An alternate main heat shield material, known as phenolic impregnated carbon ablator, behaved reasonably well in all regions of the flight envelope investigated here. However, the measured recession rate of the phenolic impregnated carbon ablator was on average 50% greater than the predicted recession by the fully implicit ablation and thermal response code, and in some cases the measured recession was as much as 150% greater (uncertainties included). Phenolic impregnated carbon ablator’s higher recession rate than predicted (in shear) resulted in adding thickness margin to the flight heat shield d...

Arcjet Testing and Thermal Model Development for Multilayer Felt Reusable Surface Insulation

Abstract: Felt reusable surface insulation was used extensively on leeward external surfaces of the shuttle Orbiter, where the material is reusable for temperatures up to 670 K. For application on leeward surfaces of the Orion multipurpose crew vehicle, where predicted temperatures reach 1620 K, the material functions as a pyrolyzing conformable ablator. An arcjet test series was conducted to assess the performance of multilayer felt reusable surface insulation at high temperatures, and a thermal-response, pyrolysis, and ablation model was developed. Model predictions compare favorably with the arcjet test data.

Preliminary Study of High Power Hydrogen Electric Propulsion for the Space Exploration

Abstract: High power electric propulsion system is strongly required for future orbital space transportation. MPD (Magneto-Plasma-Dynamic) thrusters and DC (Direct Current) arcjets with hydrogen as a propellant are promising candidates for the missions because of their high performance and adaptability to high power operation. However, to use hydrogen for long term orbital missions, its storage in orbit is crucial issue to be considered. Firstly, we proposed a hydrogen storage and feed system for electric thrusters by applying our technologies derived from the liquid hydrogen launch vehicles. Secondly, we present R&D activities of hydrogen MPD thruster and DC arcjet, especially focusing on the improvement of their performance and durability. Then, development strategy of hydrogen electric thrusters is also discussed. Finally, advantages of hydrogen electric thruster were shown compared with conventional xenon thrusters through mission analyses of lunar orbit insertion and GTO-GEO transportation.

System and method for managing momentum accumulation

Abstract: A system for managing momentum accumulation of a spacecraft in orbit may include a reaction wheel assembly for controlling an attitude of a body of a spacecraft, the body defining at least one face, and absorbing momentum, a plurality of arcjet thrusters coupled to the face to generate thrust, and a control processor coupled to the plurality of arcjet thrusters for controlling the thrust, wherein actuation of each arcjet thruster of the plurality of arcjet thrusters is configured to produce a net momentum accumulation in the reaction wheel assembly that is below a momentum saturation point of the reaction wheel assembly.

Numerical and Experimental Study of a 1-kW Hydrazine Engineering Design Model Arcjet Thruster

Abstract: Numerical and experimental study of a 1-kW hydrazine engineering design model arcjet thruster with simulated hydrazine reaction products as propellant was performed. A two-dimensional numerical model incorporating the effects of viscous dissipation, Lorentz force, ohmic heating, heat conduction, radiation loss, and pressure work was developed to model the plasma processes inside the arcjet nozzle. The flow field and heat-transfer characteristics inside the arcjet nozzle obtained from the numerical study are discussed. The effects of the electrical conductivity and the anode wall temperature on arcjet performance prediction are also discussed. Experimental tests of the engineering design model arcjet thruster with simulated hydrazine reaction products as propellant were carried out with a mass flow rate range of 20–32 mg/s and an arc current range of 8–10 A. Over the mass flow rate and arc current ranges tested in the experiment, the specific impulse of the arcjet was in the range 479–528 s, and th...

Numerical analysis of the plasma flow in an arcjet thruster

Abstract: Electro-thermal arcjet is extensively used in electrical propulsion. The flow and discharge characteristics in these thrusters vary dramatically. Thus, a relatively accurate understanding of arcjet will facilitate the development of its technique. In this paper, a two-temperature chemical non-equilibrium fluid model is employed to investigate the interior flow of an arcjet thruster with argon as the propellant. Our simulation also includes the cathode and anode in the computational domain as the electric and thermal fields are coupled in the flow and solid structure. In addition, the DSMC method is employed to investigate the downstream flow as well as the plume where the flow is rarefied. It is found that the arc is attached diffusively at 1mm downstream of the constrictor and obvious velocity slip and temperature jump is observed along the anode surface near the thruster exit.

Investigation of a shock wave in an arcjet He plasma by using an electric probe and emission spectroscope

Abstract: We developed an arcjet plasma device having a converging and diverging supersonic conical nozzle. Bright and dark emission structures were formed, depending on the gas pressure in the expansion section. In order to understand the mechanism for the formation of the structures, we evaluated the plasma parameters (electron density and temperature) by using a single probe and a visible emission spectroscope. The analysis of the probe measurements showed no temperature variation around the bright emission region. The plasma density increased significantly by a factor of two. Similar trends were also observed in the spectroscopic measurements. Moreover, the cell width (wavelength) of the shock wave calculated from the compressible fluid dynamics was in good agreement with the experimental value, indicating that this emission structure was caused by a shock cell that could be described by using compressible flow dynamics.

Experimental Investigation of Magnetoplasma Sail with High Beta Plasma Jet

Abstract: Magnetoplasma Sail (MPS) is one of the next generation in-space propulsion systems that utilize the interaction between the solar wind and the magnetosphere inflated by the plasma injection around a spacecraft. An important issue of MPS is thrust increase by the plasma injection. Experimental validation of the thrust characteristics is very important before applying the idea of the thrust increase by the plasma injection to realistic spacecraft design. In order to conduct a scale model MPS experiment, a laboratory simulator was designed and constructed inside the space chamber (2 m in diameter). As a solar wind simulator, a triple magnetoplasmadynamic arcjet generates a high-speed (>20 km/s), high-density (>10m) hydrogen plasma jet of 0.8 ms duration. A small coil (76 mm in a diameter) and Mini-MPD arcjet as a MPS simulator was immersed inside the simulated solar wind. The thrust characteristics of MPS with plasma injection have been experimentally investigated as a function of the magnetic moment M and the dynamic pressure of the injected plasma Pinf. The thrust gain is growing both with βk value which is ratio of the dynamic pressure of the injection plasma to the magnetic pressure, but the thrust saturation was observed at the high βk condition at the injection point (βk~1). The maximum thrust gain in this paper which is the ratio between the thrust with plasma injection and the thrust without plasma injection was about 4.1.

Al-water fed chemically augmented dc arcjet characteristics

Abstract: n this study, development of Al-water fed arcjet was conducted, in which water and aluminum were fed to the thruster as the propellant. Numerical investigations based on chemical equilibrium calculations were conducted to understand the details of combustion reactions and products of the electrically augmented aluminum and water reactions. From the chemical equilibrium simulation, it was shown that thrust performance of the Al-water fed arcjet was as well as that of hydrazine arcjets at low specific power range. In addition, to observe behaviors of vaporized aluminum propellant fed as a solid state rod to the arcjet and then vaporized in the discharge plenum, a novel coaxial double cathode was developed and tested. From hispeed camera images, it was shown that streams of vaporized aluminum were injected through the injection holes at a tip of the coaxial double cathode. From the spectroscopic diagnostics of the plasma in the plenum, it was confirmed that injected vapor from the injectors of the coaxial double cathode was mainly vaporized aluminum.

Temporal Evolution of Excited Level Populations in a High-Velocity Argon Plasma Flow

Abstract: A simplified collisional-radiative model is applied to a high velocity plasma flow through the arcjet nozzle to investigate the temporal evolution of excited level population densities in the selected spatial positions inside arcjet thruster. Computations are carried out for various sets of input parameters such as electron temperature, electron number density, atom temperature, and pressure. The numerical results illustrate that the extent of the ionization-recombination non-equilibrium is strongly dependent on the electron temperature and pressure, and is significantly affected by resonance radiation.

Evaporator and burner using the same

Abstract: The object of the present invention is to provide an evaporator evaporating and cracking liquid (fuel) at the same time, and secondarily atomizing the primarily-atomized liquid (fuel). According to an embodiment of the present invention, an evaporator includes a first pipe expanding unit introducing electrically-discharged gas; a second pipe expanding unit supplying fuel-air mixture of atomized liquid to the electrically-discharged gas; a neck portion electrically grounded by connecting the first pipe expanding unit to the second pipe expanding unit with a minimum passage; and an electrode nozzle forming an electrically-discharged gap at a gap with the neck portion to generate arc with applied voltage, and supplying primarily-atomized liquid to an arcjet caused by the arc to secondarily atomize the primarily-atomized liquid by the arcjet.

Study of Nucleation of CVD Diamond by DC Arcjet Method

Abstract: Arcjet plasma enhanced CVD was used to grow diamond. Nucleation of diamond was studied at the early stage of growth cause. The micro-structural probes (transmission electron microscope (TEM), high resolution electronic microscope (HREM), selected area diffraction (SAD) and electron energy loss spectra (EELS) were used to characterize the nuclei. It was found that nuclei formed following the amorphous carbon formation. The critical nucleus size was deduced to be less than 20 nm. The growth of nucleus would form the network-like structure. The incubation period of nucleation was deduced as 6–8min under the condition of high concentration of CH4 in H2.