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 W between 30 and 40 percent. The performance of the two larger half angle (20°, 15°) nozzles was similar for each of the two constrictor diameters tested. The nozzles with the smallest half angle (10°) 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 of the nozzle inserts tested. Arcjet ignition was also difficult in many tests and a glow discharge mode that prevents starting was identified.

Performance of a low-power subsonic-arc-attachment arcjet thruster

“…Curran, et al . 16 identified the occurance of restrike in 1-4 kW conventional design thrusters; however, the frequency of those oscillations was 1-2 MHz which was much higher than the average 200 kHz oscillations noted in this study. At a given flow rate and specific energy level the subsonic-arc-attachment thruster operated at temperatures much higher than those encountered with standard designs.…”

Numerical simulation of hydrogen arcjet thruster with coupled sheath model

“…Lu et al [12] pointed out that the average current density estimation based on cathode spot area may be a good one for the high-power arcjet but a poor one for the low-power arcjet. Experimental data of Curran et al [45] on medium power arcjet shows the drop in the voltage increased by two-fold and in higher current input cases to more than threefold when the mass flow rate was dropped evenly from 21.2 to 16.1 mg s −1 and further down to 11.2 mg s −1 , as can be seen in figure 2. Such a drop in voltage with a decrease in mass flow rate must be accompanied by an exponential rise in the cathode spot area.…”

“…Furthermore, the operating powers for various operating conditions predicted by the model were cross-examined with the experimental data reported by Curran et al [45]. Curran et al [45] performed an experimental investigation to evaluate hydrogen arcjet operating characteristics in the range of 1-4 kW on a series of nozzles.…”

“…Furthermore, the operating powers for various operating conditions predicted by the model were cross-examined with the experimental data reported by Curran et al [45]. Curran et al [45] performed an experimental investigation to evaluate hydrogen arcjet operating characteristics in the range of 1-4 kW on a series of nozzles. The operating power reported by Curran et al [45] on nozzle insert-1 geometry was used to examine the present model as nozzle insert-1 geometry was operated over the broadest range of test conditions.…”

“…Curran et al [45] performed an experimental investigation to evaluate hydrogen arcjet operating characteristics in the range of 1-4 kW on a series of nozzles. The operating power reported by Curran et al [45] on nozzle insert-1 geometry was used to examine the present model as nozzle insert-1 geometry was operated over the broadest range of test conditions. A gridindependence study was performed on the geometry of nozzle insert-1 prior to cross-validation of operating powers.…”