Experimental and Numerical Study on the Ablation Analysis of a Pintle Injector for GOX/GCH4 Rocket Engines

In the present study, the ablation of a pintle injector on a 500N GOX/GCH4 rocket engine under different working conditions is studied experimentally and numerically. The temperature of the pintle tip and the combustion gas in the head zone was measured in a series of experiments by the thermocouples. Moreover, a three-dimensional model was established to simulate combustion and heat transfer concurrently and analyze the ablation state of the pintle injectors. The obtained results indicate that under a low chamber pressure (pc=0.25 MPa) and an increasing O/F ratio from 0.8 to 2, the tip temperature declines first, and then rises. At the designed working condition (pc=1.05 MPa and O/F = 3.2), the pintle tip suffered serious ablation, and the microstructure analysis indicates that the ablation failure of the stainless steel pintle tip originates from chromium precipitation. This phenomenon is especially more pronounced when the temperature exceeds 1273 K, which makes the structure fragile and vulnerable. This article helps to provide an understanding of the ablation failure of the pintle injectors, and the established model is capable of giving a prediction on the ablation status of the pintle tips consistent with the experiment.