THE INFLUENCE OF SHROUDED STATOR CAVITY BOUNDARY CONDITIONS ON PERFORMANCE OF A 1.5-STAGE LOW-SPEED RESEARCH COMPRESSOR

In axial compressor, the leakage flow from labyrinth cavity has a non-negligible influence on the aerodynamic performance and flow fields of shrouded stators due to its interaction with the main stream. A number of numerical researches have been carried out to predict and understand the cavity flow. However, details about the boundary conditions between cavity and mainstream are scarce in opening literature. Comparisons between numerical and experimental results are seldom reported to verify the rationality of the connecting method. Therefore, a four-stage low-speed research compressor (LSRC) with shrouded stators in Shanghai Jiao Tong University was investigated numerically in this paper, aiming at studying the influence of different cavity boundary conditions. A steady numerical research on the front 1.5-stage (IGV-rotor-stator) of LSRC was performed using NUMECA with four connecting methods for the interface between the cavity and mainstream. The investigation reveals that different boundary conditions make great impact on the aerodynamic performance and flow fields of the compressor. Validated by the experimental data, when using the full non-matching connections between cavity and mainstream while cavity domain rotating at the nominal speed, the steady three-dimensional RANS simulation of the 1.5-stage compressor can well predict the distributions of total pressure loss and flow angle near the hub at the stator outlet. The flow mechanisms of different connecting methods are elucidated by investigating the detailed flow fields inside the cavity and near the stator hub. The full-non matching cases with different rotational speeds of cavity domain from 0 to 900 RPM are also compared to demonstrate the influence of rotational speeds on performance and flow fields.