Optimizing Dump Diffuser in Gas Turbineby Bleeding Air Method and Vortex Generators ☆

The diffuser is a component that connects the combustion chamber and the compressor in a gas turbine engine. Its main function is to slow down the airflow supplied by the compressor to enhance efficient combustion and avoid excessive total pressure loss. Therefore, the effectiveness of the diffuser is evaluated based on two values: the total pressure loss coefficient and the static pressure recovery coefficient. The smaller the total pressure loss coefficient, the better the static pressure recovery coefficient. In previous studies, attention and research have been given to the inlet angle of the diffuser. It has been observed that there is a clear flow separation on the diffuser wall before the angle of the front diffuser wall is extended to a certain degree. This increases the region of recirculation vortices, thereby increasing the total pressure loss of the system and adversely affecting the performance of the diffuser. However, there have been few studies addressing this issue. In this research, two methods are introduced to improve the diffuser: the bleeding air system and the using vortex generators. This study used numerical methods to simulate the 3D model of the diffuser. The computational results show that swirl generators and air injection methods can be observed to delay the separation process in the front diffuser and reduce the total pressure loss and improve the performance of dump diffuser by over 20%.