Distortion elimination for serpentine duct at various Mach numbers using co-flow jet active flow control

Journal article, 2024

This paper numerically investigates Co-flow Jet (CFJ) active flow control (AFC) for eliminating the AGARD M2129 serpentine inlet distortion with throat Mach number (Mth) varying from 0.42 to 0.79. The configuration was optimized at design Mth of 0.79 in a prior study. The current objective is to investigate the CFJ S-duct performance at off-design Mth with the fixed geometry. The high-order FASIP in-house code is used to conduct 3D Reynolds Averaged Navier-Stokes (RANS) simulation with the one-equation Spalart-Allmaras (S-A) turbulence model. The CFD simulation is well validated with the experiment of AGARD test cases in the studied Mach numbers. Results show that CFJ virtually eliminates the flow distortion for all the studied Mth. However, the off design Mth have lower energy efficiency. At the design Mth, CFJ requires the lowest power coefficient (Pc) to eliminate the flow separation and distortion. The exergy analysis indicates that CFJ S-duct at the design Mth has the highest system energy efficiency with the EIPR (ratio of exergy increase to the power required) exceeding 1. At the off-design Mth, EIPR is lower than 1 because the shifts of separation-onset spot and adverse-pressure-gradient region make CFJ injection and suction no longer at the most efficient location. This leads to the rising of the CFJ power coefficient even though the actual power is less. Nevertheless, the overall system is still very efficient at off-design Mth for the CFJ S-duct with the CFJ energy expenditure recovered by 72%, 90%, 96% for Mth of 0.42, 0.55, and 0.69, respectively.