Characterization of Boron-HTPB Based Solid Fuel Loaded with Iron Particles in Ducted Rocket with Energized Oxygen Supply Duct

The utilization of HTPB-based solid fuel formulations in rocket and missile propulsion
systems has recently garnered significant attention. Boron, a metalloid with high theoretical
energy potential, is commonly used as an active component in solid fuels, often
with metal additives to enhance combustion performance. Boron-based HTPB fuels are
well-suited for solid fuel ramjets (SFRJ) and ducted rockets (DR). This research aims
to study the combustion performance enhancement of B-HTPB based solid fuels, with
iron as metal additive in a laboratory-scale hybrid ducted rocket motor (HFDR) incorporating
a regenerative mixing design. The expectation is that iron would play a role in
enhancing the combustion performance of boron. In this study, the primary focus is on
determining the regression rate and chamber pressure achieved in the secondary combustion
chamber of the hybrid ducted rocket motor. The addition of iron to the base BHTPB
fuel caused an 18.6% drop-in regression rate while increasing the secondary
combustor pressure. Other key investigations such as the analysis of composition of
condensed combustion products (CCP) and pre- and post-burn grain surface analysis
are also carried out in the present study. To determine the percentage residual active
boron content, condensed combustion products (burned products) are collected and
evaluated using thermogravimetric (TG) equipment. Consequently, the characterization
analysis will provide a clear picture of the residual boron present in the burnt product.
These experiments provide data on the overall performance of our innovative static
hybrid fuel-ducted rocket design, which may be used in missile applications.