# Influence of Active Flow Control of Synthetic Jet at
## 1 Introduction  
Axial flow compressors are one of the three core components of aviation engines. Due to the extremely important role of the status, extremely demanding working environment, and extremely strict performance and safety requirements, flow control for axial flow compressors, expanding their stable working range, and improving their aerodynamic performance have always been one of the hot research topics in this field. Common flow control strategies include boundary layer suction [1, 2], plasma excitation [3, 4], casing treatment [5, 6, 7], or air injection [8, 9, 10]. These methods either require complex external piping systems or significantly reduce the efficiency of the compressor. Compared to the aforementioned measures, the active flow control method based on a synthetic jet has more obvious advantages, such as fast response, good performance, no need for complex pipelines, and low energy consumption. It is an extremely promising flow control technology that is worthy of in-depth research [11, 12]. Previous research on compressor cascades has shown that under reasonable parameters such as jet frequency and peak velocity, the synthetic jet has the effect of reducing flow separation and total pressure loss [13]. However, from the existing research, the main research objects of synthetic jets in compressors are cascades. Compared with the compressor cascade, the internal flow of the axial flow compressor is more complicated due to rotor blade torsion and high-speed rotation. Whether this active flow control technology is still effective deserves further investigation. Surprisingly, although there is still limited research on syntheticjets for axial compressors, they have attracted people's attention. For example, the literature [14; 15] conducted numerical research on the suction surface synthetic jet using NASA Rotor 37 as the research object, but these papers only discussed two operating conditions: design point and near-stall point. As one of the important indicators of compressors, it is still unknown whether the stability margin changes after being stimulated by a synthetic jet. Therefore, the influence of synthetic jet active flow control on the stability margin of the axial flow compressor is obtained by simulation in the whole working condition range, which is one of the bases of this paper.  
In addition, the author of this paper has conducted numerical simulation research on a transonic and a subsonic axial flow compressor by arranging synthetic jets on the casing over the full operating range, respectively, and obtained the influence laws of multiple parameters [16; 17]. The results indicate that active flow control based on synthetic jets at the casing position can reduce flow loss, expand the stability margin, and improve the aerodynamic performance of the compressor. However, in the internal flow of a compressor, in addition to the losses caused by blade tip leakage flow, other losses also play an important role. It is still unknown whether flow control at other locations, such as blade surface, can also have a positive effect on compressor performance. This is the second research foundation of this paper. In fact, flow control on the blade surface can directly target the flow in the compressor channel, which may be more effective in reducing flow losses.  
For civil aviation aircraft, the widely used imported stage axial fans or compressors nowadays are generally high-speed subsonic axial compressors. Therefore, based on the above analysis, previous research, and the author's existing results, this paper continues to conduct numerical research on a high-speed subsonic axial compressor rotor. The influence of a synthetic jet on the performance and stability margin of the compressor was explored by arranging it on the suction surface of a rotor blade.