Enhancement of regression rates in hybrid rockets with HTPB fuel grains by metallic additives Conference Paper uri icon


  • © 2015, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved. Low regression rates in hybrid rockets limit their use and capability. In the current paper, the implementation of micro- and nano-Aluminum and Boron particles as a regression rate enhancer is assessed on a lab-scale motor. Additive particles were individually assessed at mass loadings of 5% in hydroxyl terminated polybutadiene (HTPB) fuel grains. The combination of nano-Aluminum and Boron was also assessed at loadings of 2.5% each for a total additive loading of 5%. Test fuel grains had a length of 15.24 cm; had initial combustion port diameters of 25.4, 10, or 2 mm; and were burned in gaseous oxygen at low pressures (< 1 MPa) and moderate oxidizer mass fluxes (1-18 g/cm2-s). Traditional temporally and spatially averaged techniques and resistive-based sensor methods were applied to determine the average regression and fuel mass loss rates of plain and additive HTPB motors. The addition of nano-Aluminum (100 nm) to hybrid motors increased the surface regression rate and mass loss rate. At the conditions of this study, the effects of micro-scale Aluminum (24 µm) were negligible, and the effects of the Boron additive (100 nm-5 µm) were unfavorable to motor performance. The formulation containing both nano-Aluminum and Boron exhibited performance between the pure nano-Aluminum and pure Boron additive formulations.

author list (cited authors)

  • Thomas, J. C., Petersen, E. L., DeSain, J. D., & Brady, B. B.

publication date

  • January 2015