Gas dynamic resonance internal heating rapid catalytic ignition startup of low temperature hydroxylammonium nitrate-based monopropellant thruster

In order to achieve the rapid catalytic ignition startup of Hydroxylammonium Nitrate (HAN)-based monopropellant thrusters under low-temperature conditions (below 0 ℃), a gas dynamic resonance internal heating method is adopted to centrally heat the front section of the thruster’s catalyst bed. Three low-temperature (-9 ℃) startup tests are conducted on a 20 N HAN-based monopropellant thruster, and the heat transfer process inside the combustion chamber of the internally heated monopropellant thruster is studied through system simulation calculations. The test results show that using nitrogen as the resonant working medium, the HAN-based thruster can achieve rapid catalytic ignition and startup under low-temperature conditions, reducing the preheating time required for traditional catalyst bed electric heating from tens of minutes to tens of seconds, and significantly shortening the ignition delay time; the preheating time for low-temperature pre-pulse ignition is reduced to approximately 20 s. The heat transfer calculation results show that the resonance heater can stably output a heating power of about 30-35 W; during the pre-pulse ignition phase, the pressure rise gradient is large, and the thermal accumulation effect promotes the rapid temperature rise inside the combustion chamber. At the end of this phase, the temperature difference between the casing and the catalyst bed is about 500 ℃; in the pulse operation phase, the catalyst bed is already at a relatively high temperature level, and the temperature difference between the casing and the catalyst bed is about 200 ℃; during the continuous operation phase, due to the continuous supply of propellant, the maximum temperature inside the catalyst bed can reach about 1 150 ℃, with a temperature difference of about 600 ℃ from the casing. The application of gas dynamic resonance heating method can realize the rapid catalytic ignition startup of HAN-based monopropellant thrusters under low-temperature conditions.