Arcjet rocket

About: Arcjet rocket is a research topic. Over the lifetime, 1121 publications have been published within this topic receiving 9687 citations. The topic is also known as: Arcjet.

Low-Power Helium Pulsed Arcjet

Abstract: An electrothermal thruster that operates in a rapid-pulse mode at low power ( 85%of the initial stored energy is transferred to the arc in a unipolar pulse. The arc discharges occur in a cylindrical capillary upstream of a converging–diverging nozzle, and all of the energy additionoccurs in the subsonic region. Tests with heliumpropellant are conducted for two 20-deghalf-angle conicalnozzleswith area ratiosof 20 and230.Thrust levels from14 to 31mNaremeasured,andamaximumspeciŽ c impulse of 313 s is achieved with 36% efŽ ciency at 119 W. A time-dependent, quasi-one-dimensional numerical model is developed to evaluate energy losses using a time-marching procedure, and comparisonwith experimental results is good. Heat transfer losses to the wall in the subsonic region are found to be the primary energy-loss mechanisms. SpeciŽ c impulse is strongly affected by wall temperature. Viscous effects become important as the speciŽ c energy increases above 12 MJ/kg and the throat Reynolds number falls below 1 £ 103.

Numerical Study of the Electromagnetic Control of a Weakly Ionized Flow around a Blunt Body: Role of an Insulative Boundary in the Flow

Abstract: The electromagnetic flow control was simulated using magnetohydrodynamic equations including the Hall effect to clarify the electromagnetic effects measured in an arcjet flow. The result showed that the combined effect of the Hall effect and an insulative boundary in the flow activates the electromagnetic flow control: an ideal uniform ionized flow without any insulative boundary in the flow was found to be unsuitable to investigate the electromagnetic flow control experimentally. In addition, the present study computes the flow with an artificial insulative plume boundary to imitate the non-uniformity of the experimental flow. As a result, the measured drag increase was reproduced if an artificial insulative boundary is set to the location identical to the plume radius estimated on the basis of the measurements. Consequently, the measured drag increase in the arcjet flow results from the plume boundary serving as an insulative boundary.

Medium power hydrogen arcjet performance

Abstract: An experimental investigation was performed to evaluate hydrogen arcjet operating characteristics in the range of 1 to 4 kW. A series of nozzles were operated in modular laboratory thrusters to examine the effects of geometric parameters such as constrictor diameter and nozzle divergence angle. Each nozzle was tested over a range of current and mass flow rates to explore stability and performance. In the range of mass flow rates and power levels tested, specific impulse values between 650 and 1250 sec were obtained at efficiencies between 30 and 40 percent. The performance of the two larger half angle (20, 15 deg) nozzles was similar for each of the two constrictor diameters tested. The nozzles with the smallest half angle (10 deg) were difficult to operate. A restrike mode of operation was identified and described. Damage in the form of melting was observed in the constrictor region of all the nozzle inserts tested. Arcjet ignition was also difficult in many tests and a glow discharge mode that prevents starting was identified.

Two-Dimensional Ablation and Thermal Response Analyses for Mars Science Laboratory Heat Shield

Abstract: This paper examines transient simulations performed to predict in-depth thermal response and surface recession of the proposed heat shield material for the Mars Science Laboratory entry capsule, that is, phenolic impregnated carbon ablator. The finite volume material response code used in this paper solves the time-dependent governing equations, including energy conservation and a three-component decomposition model, with a surface energy-balance condition and a moving grid system to predict shape change due to surface recession. The predicted in-depth thermal response of heat shield material generally agrees well with the thermocouple data under various arcjet conditions. Also, two-dimensional computations using aerothermal environment for Mars entry (derived from a proposed three-sigma trajectory) are performed around the heat shield shoulder region, where high heating occurs as the result of angle of attack. Parametric studies are conducted to examine the effects of carbon-fiber orientation, material p...