Aluminum Combustion Can Drive Instabilities in Solid Rocket Motors: T-Burner Study

摘要

This paper reports experimental and numerical works devoted to the role of aluminum combustion on the stability of solid rocket motors. An experimental setup, known as the velocity-coupled T-burner, which provides measurements of the contribution of aluminum combustion to stability, has been developed and used. Experiments unambiguously show that aluminized propellants have a strong destabilizing contribution, whereas nonaluminized do not. This destabilizing behavior is found to depend much on aluminum agglomerate size distribution. In addition, two-phase numerical simulations are conducted on the setup and confirm experiments. It is found that the instability arises due to a thermoacoustic coupling between pressure waves and the heat release from aluminum combustion. Simulations also stress the role of aluminum agglomerate particle size as in experiments. This work experimentally and numerically proves that aluminum combustion represents a source of instability in solid rockets that should not be overlooked. This suggests that the widely accepted viewpoint that particle phase always damps pressure waves may not be always true for some aluminized propellants.