多素材3Dプリンタ製燃料後退計測機能付き固体燃料の研究

抄録

Prototype solid fuels for a hybrid rocket were fabricated by using a multi-material 3D printer and conductive thermoplastic composite to construct a ladder-shaped resistance inside the electrically-insulated thermoplastic solid fuel and to measure the time-resolved fuel regression. In this type of fuels, the remaining fuel thickness is monitored by the voltage applied to the resistance that changes according to the number of rungs of the ladder-shaped resistor. For comparison with the proposed measurement, the time-resolved fuel regression was optically measured by using a high-speed video visualization. The solid fuel regression history with the proposed technique agreed well with that with the optical measurement considering the uncertainties in the measurement methods. Errors that cannot be explained by these uncertainties were found to be ±0.15 [mm], corresponding to ±1 layer of the stacking pitch of the 3D printer applied in this study. This paper also shows a preliminary firing test result using a post-processed 3D-printed cylindrical solid fuel grain as a preparation for the application of the proposed technique to the cylindrical solid fuel.