Boron has been considered most attractive fuel for ducted rockets because of its high combustion heat with oxygen. However, boron was found to be impractical as the fuel because of its poor combustion efficiency due to the meager ignition characteristics. Boron had to be ignited and combusted forcibly in the residence time of the recirculation zone. In this study, we focused on the case of another ignitable metal particles becoming the ignition source of boron. Magnalium was selected as the ignition source. In order to elucidate the effects of magnalium, three types of experiments were conducted. To obtain the basic properties of metals, thermogravimetry and differential thermo-analysis were conducted. The ignition delay time was measured with an electronic furnace, and combustion efficiency was obtained by using a connected-pipe ducted rocket. It was clarified that the ignition delay time of the mixture could be divided into two time regions, earlier and later regions than that of the single magnalium particle. The combustion efficiency could be distributed. The combustion efficiency when the gas generator contained boron can improve only if the earlier time region can be selected actively.
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