Modeling and Simulation of Solid Propellant Particle Path in the Combustion Chamber of a Solid Rocket Motor
ABSTRACT In a solid rocket motor (SRM) using aluminized composite solid propellant and a submerged nozzle, a two-phase flow needs to be investigated by both experiment and computation. The boundary conditions for the ejecting particles constrain their trajectories, hence these affect the two-phase flow calculations, and thus significantly affect the evaluation of the slag accumulation. A new method to determine the velocities of particles on the solid propellant surface was developed in the present study, which is based on the RTR (X-ray Real-time Radiography) technique and coupled with the two-phase flow numerical simulation. A method was developed to simulate the particle ejection from the propellant surface. The moving trajectories of metal particles in a firing combustion chamber were measured by using the RTR high-speed motion analyzer. Image processing software was also developed for the RTR images, so the trajectories of particles could be obtained. Numerical simulations with different propellant-surface boundary conditions were performed to calculate particle trajectories. By comparing the two trajectories, an appropriate boundary condition on the propellant surface was referred. The present method can be extended to study the impingement of particles on a wall and other related two-phase flows.
Journal of Spacecraft and Rockets 01/1984; 21(1):47-54. DOI:10.2514/3.8606 · 0.47 Impact Factor
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ABSTRACT: A parametric investigation was carried out, by analytic and numeric solution of a simple Eulerian-potential-flow/Lagrangian-particle-tracking formulation, of the effect of metallized-grain configuration on the retention of slag within the cavity of a first-stage-type solid-rocket-propellant motor. In particular, a relatively short motor with the grain deeply slotted near the aft end, a relatively long motor also with the grain deeply slotted near the aft end, and a long "conocyl" motor with axially distributed slots (such that much of the aft end was grain filled during the entire burn) were compared. The same initial grain bore and the same casing diameter pertained to all three motors, and in each case the nozzle was taken to be deeply recessed ("submerged"). It was found that, over a wide range of plausible particle sizes, the accumulation of slag (here, molten aluminum oxide) at the aft end is appreciably less for the short motor and for the conocyl motor than for the long motor. Further, it was found that the effect of a plausible flight-acceleration history on slag retention, relative to a standard-gravity calculation, would be discernible only for larger particle sizes, above roughly 200-mum diameter.Journal of Spacecraft and Rockets 09/1992; 29(5):697-703. DOI:10.2514/3.55646 · 0.47 Impact Factor
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ABSTRACT: Ground tests of solid propellant rocket motors have shown that metal-containing propellants produce various amounts of slag (primarily aluminum oxide), which are trapped in the motor case, causing a reduction, albeit small, of total impulse. Although not yet definitely established, the presence of a liquid pool of slag also may contribute to nutational instabilities that have been observed with certain spin-stabilized, upper-stage vehicles. Because of the rocket's axial acceleration-absent in the ground tests-estimates of in-flight slag mass have been very uncertain. Yet such estimates are needed to determine the magnitude of the control authority of the systems required for eliminating the instability. This paper describes a physical model of the slag transport in the motor and uses it to predict the in-flight slag mass from ground tests. Based on reported ground tests, it is concluded that the distribution function for slag droplet masses in the dynamically significant range is proportional to the - 1.50 power of the mass. For geometrically similar motors with a given ratio of radial to axial acceleration, the trapped slag mass is shown to be proportional to the fourth power of the motor diameter.Journal of Propulsion and Power 01/1992; 8(1):45-50. DOI:10.2514/3.23440 · 0.61 Impact Factor