Experimental and numerical study on supersonic split line nozzle in a solid rocket motor

The supersonic split line (SSSL) nozzle is a novel thrust vectoring nozzle that can amplify the lateral force to enhance the thrust vectoring performance of the nozzle. In this paper, experimental and numerical simulation methods are combined to investigate its thrust vectoring performance under different working conditions and the evolution process of its internal flow field, aiming to provide theoretical support for the development and application of SSSL nozzle. Hot-fire tests were conducted at five swing angles (0°, 3°, 5°, 7°, and 10°), with the axial and lateral forces of the solid rocket motor measured. Test results show that the nozzle achieved an amplification factor of 1.32∼1.43, which decreased with increasing swing angle. Based on three-dimensional numerical simulations using Fluent, thrust calculations of the SSSL nozzle were carried out. The numerical results are in good agreement with the experimental data, and the maximum deviation of the thrust calculation is within 3.5%. The effects of swing angle and nozzle pressure ratio (NPR) on the thrust performance of the SSSL nozzle were investigated numerically. The results show that the amplification factor of the nozzle decreases with increasing swing angle in the range of 3° to 18°, consistent with the test conclusion; an excessively low NPR would disrupt the nozzle’s vector amplifying effect, resulting in the amplification factor '1; as NPR increased, the amplification factor increased monotonically and tended to a constant value.