Session: 31-13 Flow Control

Paper Number: 126084

126084 - An Experimental Investigation of the Corner Separation Control in a Compressor Cascade Using Spatially Oscillating Jet 

The three-dimensional corner separation, as an inherent flow feature of the cascade corner regions, is commonly observed, presenting a challenge for designers to limit the resulting losses and blockage. In this study, an actuator with the ability to generate spatially oscillating jets, known as the sweeping jet actuator (SJA), is employed to manage the corner separation in a CDA profile. These fluidic actuators have no moving parts and is only based on the inherent fluid dynamics via a high-gain bi-stable fluid amplifier. As a result, they can achieve higher operating frequencies and flow rates, which has led to their increasing application in active flow control. The current experiments were performed in a low-speed wind tunnel with an inflow Mach number of 0.23. Five-hole probe measurements and the oil flow visualizations were carried out to demonstrate the performance and physics of the flow field. The transient data were also obtained using the dynamic pressure sensors to get insight into the unsteady characteristics.

The SJA was integrated into the cascade endwall through 3D printing, with dimensions constrained to within 15mm, achieving a maximum operating frequency of approximately 1400Hz. A detailed analysis of the influence of injection axial position and injection momentum on the control effect was conducted. The results indicate that the spatially oscillating jets generated by SJA effectively inhibit the transverse migration of the boundary layer on the endwall. Moreover, this control is achieved without a substantial increase in mixing losses, thereby significantly restraining the development of corner separation. The optimal control configuration is obtained when placing the SJA near the leading edge and employing 0.13% of the mainstream flow rate. This setup results in a significant reduction of 14.2% in non-dimensional total pressure loss. Additionally, it delays the onset of corner separation by 16.5% and reduces the spanwise extent of separation by 30.9%. However, when the excitation location moves downstream, the sweeping jet becomes less effective in inhibiting the migration of low-energy fluid. This shift induces a region of high losses near the endwall surface, leading to a notable decline in control effectiveness.

Furthermore, an SJA with a lower operating frequency was also designed to assess the impact of excitation frequency on control effectiveness. The results reveal that the high-frequency SJA influences the fluid closer to the wall, leading to reduced mixing losses and, consequently, enhanced control efficiency. The results highlight the superior characteristics of the SJA in controlling the corner separation. In the future, this technology is expected to play a crucial role in the development of closed-loop adaptive flow control techniques.

Presenting Author: Pengcheng Yang Harbin Institute of Technology

Presenting Author Biography: Doctoral student in Harbin Institute of Technology, engaged in research on internal flow control technology in turbomachinery components, mainly focusing on developing effective active and passive flow control technologies for low-pressure turbine laminar flow separation and compressor corner separation;

Authors:

Pengcheng Yang Harbin Institute of Technology
Shaowen Chen Harbin Institute of Technology
Guanyu Liu Harbin Institute of Technology
Shiqi Wang Aero-Engine Academy of China, Aero-Engine Corporation of China