Performance analysis of N2O/CO2 oxidizer mixture with paraffin based micro-aluminum and magnesium fuels for mars ascent vehicles

Abstract

The objective of this research is to perform experimental test of a hybrid rocket motor by using N2O/CO2 mixture as the oxidizer and paraffin wax as fuel with the addition of metallic powders such as micron size aluminum and magnesium. A lab scale hybrid motor with 70 mm grain length and 30 mm outer grain diameter is used to measure the key performance parameters such as specific impulse (Isp), regression rate (R-), and combustion efficiency (?comb). The 3-micron sized aluminum powder with %98.9 purity has been used as fuel additive in the paraffin wax. Numerous tests are performed with N2O/CO2 mixtures as the oxidizer. CO2 as a saturated liquid is mixed with liquid N2O between 8 to 30% by mass in order to measure the motor performance characteristics such as average regression rate, r- and combustion efficiency, ?comb. Experiments were performed in the blowdown mode using the self-pressurizing capability of the mixed oxidizer around 45-50 bar. Chamber pressure of the hybrid motor was in the 15-30 bar range. Successful ignition and motor operation of the mixed oxidizer is achieved all the way up to 22% CO2 in the mixture. In addition, 62 micron magnesium powder is also used to evaluate the performance parameters of micron-sized aluminum based hybrid motor. Experiments showed that magnesium based fuels can combust with over 25% CO2 in the oxidizer mixture due to the easy combustibility nature of the Mg. Although Mg indicates lower regression rate characteristics than Al, usually bring higher combustion efficiency out. Therefore, initial conclusion from this study indicate that mixing CO2 with N2O is a viable method of burning CO2 in a practical rocket system for Mars missions. Copyright © 2019 by the International Astronautical Federation (IAF). All rights reserved.