ETD

• combustion
• green propulsion
• hydrogen
• hydrogen peroxide
• ignition
• space
• water propulsion

Water promises unique performance and advantages as propellant for in-space propulsion technologies and operations. To overcome some of the current limitations of chemical Water Electrolysis Propulsion (WEP), the University of Pisa is developing a 200 N-class bipropellant thruster based on high-concentration hydrogen peroxide (HTP) and gaseous hydrogen (GH2). This work is carried out as part of the European EIC Pathfinder project Green SWaP (Green Solar-to-propellant Water Propulsion), which is developing the necessary technologies to bring this innovative water propulsion concept to reality.

The present study consists of a preliminary feasibility analysis of direct spark ignition inside the combustion chamber of the thruster. The mixture consists of the gaseous decomposition products of HTP and gaseous hydrogen (GH2). The major combustion theory in this aspect is reviewed and four key parameters for flame kernel evolution are identified: critical radius, characteristic time, critical power and reference ignition energy.

To evaluate the flame kernel parameters, a Python program was developed. First the code was validated by comparing the data from H2/O2 and H2/air combustion experiments. The simulation data shows a trend similar to that of experiments and the order of magnitudes are comparable.

Based on these results, key parameters are analyzed using the code, for HTP/GH2 case and for different thruster operating scenarios. The data from these simulations favors the use of conventional spark plugs, but the spark location need to be verified by analyzing the flow initially by numerical simulations and then by experiments.