Navier-Stokes Analysis of Scale Effects on Ablation in Carbon-Carbon Rocket Nozzles

A study is conducted to predict Carbon-Carbon nozzle recession behavior in solid rocket motors for wide variations of propellant formulations and motor operating conditions. The numerical model considers the solution of Reynolds averaged Navier-Stokes equations in the nozzle, heterogeneous chemical reactions at the nozzle surface, variable transport and thermodynamic properties, and heat conduction in the nozzle material. Results show that the ablation rate is affected by the dimension of the nozzle as well as by the boundary layer thickness at the nozzle entrance. The combined effect of both scale and boundary layer thickness at the nozzle entrance is also analyzed.