Influences of nozzle pressure ratio on flow characteristics of serpentine multi-stream supersonic nozzle

The serpentine multi-stream supersonic nozzle (SMSN) is adopted for the multi-stream exhausted system of the Adaptive Cycle Engine to enhance the stealth performance of next-generation fighter. In this paper, the effects of the nozzle pressure ratio (NPR) on the flow characteristics of the SMSN were studied using the numerical simulation method validated by experimental data. The serpentine configuration leads to the nonuniform pressure distribution. At the mixing position, the expansion and shock waves are generated due to the pressure difference. As the NPR increases, the flow separation and shock wave in the mixing section gradually weaken and disappear. The thrust coefficient rises first and then drops. Due to the flow separation under the design condition, the thrust coefficient is the largest at MPR=6 and TPR=2.272. As the MPR increases at TPR=1.893, the compression effect of the main flow is enhanced on the upper third flow. The thrust coefficient rises first and then drops, and reaches the maximum at MPR=6. As the TPR increases at MPR=5, the compression effect of the main flow is weakened on the upper third flow. The thrust coefficient rises first and then drops, and reaches the maximum at TPR=2.272.