Numerical Analysis on Nozzle Erosion in Hybrid Rocket Motors with Different Injection Parameters

This paper investigates the effect of injection parameters on the nozzle erosion in hybrid rocket motors. Hydrosyl-terminated polybutadiene (HTPB) and 90% hydrogen peroxide $\left(\mathrm{H}_{2} \mathrm{O}_{2}\right)$ are adopted as propellants. Two-dimensional steady numerical simulations of gas-liquid two-phase flow are performed. An united numerical calculation of oxidizer atomization and vaporization, propellant combustion, and nozzle thermochemical erosion is conducted. Different oxidizer droplet diameters are considered, and characteristics of combustion flow field and nozzle erosion are discussed. The simulation results indicate that when the droplet diameter increases from $25 \mu \mathrm{m}$ to $50 \mathrm{~km}$, the residence time increases from $3.21 \mathrm{~ms}$ to $22.6 \mathrm{~ms}$. The average fuel regression rate, combustion temperature, chamber pressure, and characteristic velocity of liquid-phase injection are higher than that of gas-phase injection. The throat erosion rate of liquid-phase injection varies from 0.0363 mm/s to 0.0387 mm/s, while that of gas-phase injection is 0.0244 mm/s. When droplet diameter is greater than $50 \mu \mathrm{m}$, the throat erosion rate decreases.