Unique Phenomena Resulting from Three-Dimensional Flows inside Solid Propellant Rockets

Paper number

IAC-06-C4.3.02

Author

Prof. Toru Shimada, Japan Aerospace Exploration Agency (JAXA)/ISAS, Japan

Year

2006

Abstract

The demand to the high reliability and high performance of a space transportation system is still higher these days. It is a role of system engineering to bring a whole system together by integrating element technologies, and using modeling and numerical simulations, proof experiments, and statistical procedures. The accuracy and certainty in modeling and simulation depend on the understanding level of the phenomenon. The high reliability and high performance cannot be obtained without the refined technology supported with the promotion of the understanding.

The combustion of the composite solid propellant is an extremely complex physico-chemical phenomenon. It is the behavior of gas-particle multi-phase flow to rule spatial and temporal changes of the heat feedback on the burning surface. It is, therefore, essentially important to understand the flow behavior accurately to evaluate the oscillatory and the erosive burning, the ablation of thermal protection systems, and the entire system performance of solid rocket motors (SRM).

However, the complexity of SRM internal flow becomes barriers to know the flow behavior. There are unique flow-induced phenomena whose mechanisms have not been fully understood. In this lecture, such flow phenomena are discussed. They are the generation of the roll torque by the vortical flow in SRM and a peculiar ablation of a nozzle by interference with a supersonic turbulent flow.

Roll torque has been observed during the burning of the first-stage motor, M-14, of the Mu-V launch vehicle in all six flights since 1997. The roll torque observed in a few seconds after the launcher departure is a considerably big torque so that it cannot be explained by aerodynamic force and misaligned thrust. It is suggested from the data in literature that it may occur by the acoustic streaming.

The ablation pattern that appears on a nozzle liner is discussed as another example. The ablation patterns called cross-hatching and striation in the nozzle exit cone of a rocket may occur, and they may be connected also with a practical problem when the extent is strong. These patterns can be confirmed by a simple firing test.

Detailed mechanisms of these two flow phenomena are not known enough. The complexity that originates in three dimensionality and unsteadiness makes it difficult to understand the mechanism. The level of system engineering of the rocket design is sure to be improved by these phenomena being clarified. It is expected earnestly that the elucidation will be tackled by many researchers of rocket science.

Abstract document

IAC-06-C4.3.02.pdf

Manuscript document

IAC-06-C4.3.02.pdf (🔒 authorized access only).

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