Investigation On Solid Rocket Motor C/C Throat Erosion Modeling And Simulating

Solid rocket motors are widely used in military and aerospace fields.Nozzle throat is the key component of solid rocket motor,and it's working condition is very extremely.The ablation is the main failure mode of a nozzle throat.C/C composite materials have good properties,such as high temperature resistance,light weight,etc.Those properties make the C/C composite materials widely used in the manufacture of throat lining parts.Therefore,the ablation performance research of the C/C throat is becoming more and more valuable in the field of engineering application.The objective of this work is starting with the ablation theory,after comprehensive analyzing the physical and chemical processes which occur in complex gas environment of the C/C throat,a point that C/C throat thermochemical ablation is affected by chemical reaction rate and diffusion rate,and the smaller rate decides C/C throat ablation rate.A three equation model is established based on the fact that the OH can't be neglected in the process of ablation.And a boundary layer model is established with the principle of mass conservation,momentum conservation and energy conservation.Through the numerical simulation,the thermal coupling between the flow and the solid is calculated taking ablation reaction absorb heat is occurred into account.Thus the throat temperature distribution after ablation is achieved.Compared with the temperature distribution that has no ablation,the differences between the two cases are analyzed.The ablation rates of three and two equation models of C/C throat are calculated respectively under the same condition,and the experimental results show that the three equation model is more reasonable,which shows that the effect of OH in the C/C throat ablation process is not negligible.The influence of different factors such as combustion chamber pressure,outer boundary conditions,gas phase reaction and type of propellant is studied and five conclusions can be found.The results show that the C/C throat ablation rate increases while pressure increases.When the pressure is higher,although the OH content in the gas is less,the impact on the ablation rate is more and more obvious.The C/C throat ablation rate increased first and then decreased along the nozzle axis,finally come to stable at the existence.The largest ablation point is in the upstream of the throat instead of throat.The outer boundary condition can influence the ablation rate mainly by changing the throat wall temperature.In the process of C/C throat ablation rate calculation,it cannot be simply considered that the throat wall is adiabatic environment.The gas content changes in gas phase reactions.Although the increase of H2 O content lead to the increase of ablation rate,however,the decrease of CO2 also lead to the decrease of ablation rate.In this way,the combination of the two factors has little effect on the ablation rate.So the gas phase reactions can be ignored in the calculation of C/C throat ablation rate.The C/C throat ablation rate decreases when the content of aluminum in the propellant increases from 0 to 3.5% and increases when increasing from 3.5% to 16% and finally decreases gradually when the aluminum content continues growing.