Aluminum Combustion Driven Instabilities in Solid Rocket Motors

Combustion response of an aluminum droplet burning in air

“…Unsteady compressible Navier-Stokes equations are solved with the perfect gas equation of state, using our in-house code CPS [10,14]. It adopts a finite-volume technique on unstructured mesh.…”

“…Nevertheless, it has been recently shown that aluminum combustion can drive thermoacoustic instabilities in rockets due to a coupling between motor acoustics and unsteady aluminum heat release [10,11]. This previously unreported result in solid propulsion emphasizes a crucial role of unsteady aluminum combustion.…”

Some recent advances in the instabilities occurring in long Solid Rocket Motors

“…16,17 A further analysis of these computations was made possible by the fluctuating energy balance post-processing. 17 This method gives information that can be compared to the acoustic balance.…”

Detailed analysis of a quench bomb for the study of aluminum agglomeration in solid propellants

“…The Al combustion model is the usual D 2 square model. Equations solved for the gas and particle phases can be found in [11]. An operator splitting is used for particle source terms (mass, momentum, and energy) when using explicit time-stepping: ¦rst, conservative variables W n are updated without source terms to an intermediate state W * for time step -t. Then, the di¨erential equation dW/dt = S is solved from W * to the ¦nal state W n+1 .…”

“…Additionally, it also has some profound e¨ects on unsteady motor operation. Although particles are generally employed for instability damping, recent research [11] showed that large burning agglomerates are prone to trigger thermoacoustic instabilities in solid rocket motors. Because the role of particles on motor operation can be signi¦cant, those particles need to be characterized accurately ¡ notably, size and mass fraction.…”