Effects of Angle and Frequency of Nozzle Swing on Pressure Oscillation Response in Solid Rocket Motors

The instability of the combustion may be induced by the swing of the nozzle, and the problem of instability has been paid great attention by the researchers at home and abroad. To investigate the effects of the swing angle and frequency of nozzle on pressure oscillation in combustion chamber, the analysis on the pressure variation and response law under different swing angle and frequency in combustion chamber of solid rocket motors has been conducted by numerical simulation, on the condition that the burning area of grain and throat diameter are given at certain time and the swing method is fixed on sine. The results show that on condition of the fixed swing frequency, when the swing angle is changed, the average pressure of combustion chamber increases slightly with time. When the swing angles are 3° and 7°, the average pressure increment is more pronounced than the other angles. With the increase of the swing frequency, the amplitude of low frequency response caused by the swing of nozzle is increasing under the same swing angle. Pressure oscillation caused by swing nozzle is mainly concentrated in the low frequency region below 100Hz. © 2018, Editorial Department of Journal of Propulsion Technology. All right reserved.