Control of Vortex-Induced Oscillations in a Model Solid Rocket Motor: Flow Characterization and Secondary-Injection Experiments

摘要

Vortex-driven instability in a solid rocket motor and its active control via secondary injection were studied in a cold-flow experimental model. All tests were conducted in an 86-cm-long, 5- cm-square airflow chamber. Twin orifice plates at the center of the chamber produced a 21 5-Hz vortex-driven pressure instability with 2% peak-to-peak oscillations near the first longitudinal chamber mode. Hot-wire anemometer data at the vortex shedding frequency indicate that the organized structures occur between the two orifice plates located at the center of the chamber and not between the orifice pair and the exit nozzle. Exploratory secondary-injection active control experiments were performed by pulsing a fast-acting solenoid valve at the upstream end of the chamber. The chamber pressure response (without orifice plates) to the pulsating secondary injection was characterized for various flow rates at frequencies of 100 and 150 Hz. Pressure perturbations of sufficient magnitude (1-5% peak-to- peak)to counter the vortex-driven instabilities were demonstrated. An active control scheme utilizing the present secondary-injection hardware will be the subject of future studies.