Two-Dimensional Modeling of Ablation and Pyrolysis with Application to Rocket Nozzles

Abstract

A new two-dimensional ablation analysis code (MOPAR-MD) capable of modeling pyrolyzing thermal protection system materials is presented. Favorable agreement with analytical solutions and results from other (one-dimensional) ablation solvers for a wide range of test cases indicates a correct implementation consistent with other codes. This new material response code can be coupled to the LeMANS reacting flow solver. New capabilities required for modeling nozzle flowfields are added to LeMANS, including the Menter baseline and shear stress transport turbulence models and a “two-gas” method for capturing the thermodynamics of gas–particle flow found in many rocket nozzles. These updated codes are used to perform uncoupled simulations, predicting the thermal and ablation response of the HIPPO nozzle test case. Radiation is found to have minimal impact on the response of the throat and downstream portions of the rocket nozzle, but remains significant for the motor chamber and upstream portions of the nozzle. Enthalpy conductance and surface recession of the nozzle are found to be quite sensitive to the assumed wall temperature, underscoring the need to perform coupled flowfield/ablation simulations to more accurately capture the convective heating environment. All simulations of the HIPPO nozzle predict substantially greater surface recession than measured experimentally. Several potential causes for this discrepancy are identified, many of which could be resolved by performing fully conjugate, coupled flowfield/ablation simulations.