Numerical and experimental constrictor flow analysis of a 10 kW thermal arcjet

In a thermal arc jet the main heating of the propellant takes phce in the constrictor. To gain more insight into arcjet operation and in order to obtain some experinIental data on the shape, sue and stability of the arc channel inside the constrictor, a modified version of the water-cooled T T I thruster was built. A window was inserted in the nozzle throat to observe the discharge channel in the constrictor. With a fast CCDCamera images of the arc were taken and with image processing methods the fluctuation of the arc was investigatedfor different working conditions with hydrogen as propellant. The camera system was calibrated to measure absolute intensities with a tungsten band lamp. Thus it was possible to determine two dimensional temperature profiles j o m electron continuum and jom line intensity of the H, and the Ha line. Results of this temperaiure measurement inside the constrictor are presented for different operation points In the second section an analytical method is described to calculate the flow conditions inside the constrictor. The method is based on a previously developed Dual Channel Model. That model was extended by a third channel where the transition region between the hot column and the cold gas is considered. The first version of the model is developedfor hydrogen as propellant. The calculation results are compared with measurements.