Abstract

The estimation of erosive burning is of great importance for the internal ballistics computation of a solid rocket motor (SRM) with a large aspect ratio. Because of the variety of parameters affecting erosive burning, most of the erosive burning models developed in earlier years usually contain unknown constants that need to be identified by a trial-and-error procedure for each SRM. Based on an SRM with a cylindrical grain, a new erosive burning model, which coupled the heat transfer between the gas and grain, was proven to be effective previously. To expand the scope of application of this model, in this paper, earlier and new erosive burning models were used in the transient one-dimensional internal ballistics computation, to obtain the internal ballistics for a star-grain SRM. A comparison between the computational and experimental results indicated that both the earlier and new erosive burning models can obtain results with good accuracy for a star-grain SRM. The paper shows that with no constants to be identified, the Ma model is easy to use and has the potential to predict the erosive burning rate before a firing test.

Highlights

  • To obtain good performance, a large aspect ratio is often used in different solid rocket motor (SRM)

  • In the simplest models [1,2,3,4], it is considered that there is a linear relationship between the erosive burning ratio and a key variable, such as velocity, Mach number, mass flux through the port, and so on

  • When such a model is used for internal ballistics computation, the two constants need to be identified by a trial-and-error procedure

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Summary

Introduction

A large aspect ratio is often used in different SRMs. In these SRMs, the augmentation of the burning rate, due to erosive burning, may affect the internal ballistics dramatically, and can sometimes even cause catastrophic consequences. The ignition model plays an important role in the internal ballistics computation of SRMs. A popular and simple ignition model used by many researchers assumes that the propellant begins to burn once the propellant surface reaches a critical temperature [22]. Numerical 1D heat transfer computation, using the finite element method or finite volume method, can be carried out to evaluate the surface temperature This method can obtain the propellant surface temperature history for each fluid cell of the 1D fluid domain with quite good accuracy. The computational results met the experimental results well This validates the two universal erosive burning models and the code, and proves that the Ma model has the potential to predict internal ballistics before a firing test of real SRMs

Models
Erosive
Ignition Model
Geometric Correlations
Numerical Procedure
Results and Analysis
Results
Conclusions internal a star-grain
Full Text
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