Ignition-combustion mechanisms in insensitive HTPE propellants: Bridging thermal stability and flame dynamics

Hydroxyl-terminated polyether (HTPE)-based insensitive propellants exhibit unique combustion behaviors governed by their thermal stability and binder-phase dynamics. This study systematically investigates the ignition-combustion mechanisms of HTPE propellants through multi-scale characterization and modeling. Experimental results reveal that the HTPE binder forms a dynamic “liquid-phase lubricating layer” upon heating, delaying oxidizer decomposition and extending ignition delay times by an order of magnitude compared to conventional HTPB propellants. High-speed imaging and thermal analysis demonstrate that this layer modulates condensed-phase reactions, inducing cyclic Al particle agglomeration and stabilizing flame structures. The burning rate pressure index (0.337) aligns with composite propellant norms, confirming self-regulating combustion stability. A modified ignition delay model incorporating phase-change effects and a combustion framework integrating binder encapsulation dynamics further elucidate how HTPE's phase change decomposition behavior governs oxidizer gasification and flame propagation. These findings establish new insights into designing thermally stable, low-sensitivity propellants with tunable combustion performance.