Effects of a Slow Gas-Phase Reaction on the L(*) Instability in Solid-Propellant Rockets

L*-instability stemming from the interaction between the thermal relaxation in the solid propellant and the bulk-mode gas motion inside the combustion chamber is examined theoretically and numerically. The explosion reaction, following the quasisteady fizz reaction occurring near the burning surface, is analyzed for its unsteadiness and strong dependence on the chamber pressure and pressure transient. For this purpose, the asymptotic analysis exploiting the large activation energy of the explosion reaction is performed. The linear-stability results show that a system becomes more unstable due to the nonvanishing induction length in comparison with the quasisteady-flame limit, in addition to capturing all the trends for L*-instability obtained by the quasisteady flame theories. The current dp/dt-extinguishment criterion seems better in predicting the extinction trends in a low-pressure range than those obtained by quasisteady flame theories. By numerically solving the problem, large-amplitude, low-frequency oscillations are found to be associated with repeated extinctions and reignitions of the explosion reaction. In addition, the incomplete combustion is explained and many of the known extinction phenomena under high depressurization are captured. On the other hand, the unsteady process at the subsurface is pointed out as a possible cause for the chuffing.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Theoretical and Applied Mechanics

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2014

Author dc:creator

• Lee, Hyoung In

• Applied Mechanics
• Engineering, Aerospace
• Engineering, Mechanical

Identifier

(UMI)AAI8815380

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/71697