Prestall Behavior of a Transonic Axial Compressor Stage via Time-Accurate Numerical Simulation

Abstract

Computational fluid dynamics calculations using high-performance parallel computing were conducted to simulate the prestall flow of a transonic compressor stage, NASA compressor Stage 35. The simulations were run with a full-annulus grid that models the 3D, viscous, unsteady blade row interaction without the need for an artificial inlet distortion to induce stall. The simulation demonstrates the development of the rotating stall from the growth of instabilities. Pressure rise performance and pressure traces are compared with published experimental data before the study of flow evolution prior to the rotating stall. Spatial fast Fourier transform analysis of the flow indicates a rotating long-length disturbance of one rotor circumference, which is followed by a spike-type breakdown. The analysis also links the long-length wave disturbance with the initiation of the spike inception. The spike instabilities occur when the trajectory of the tip clearance flow becomes perpendicular to the axial direction. When approaching stall, the passage shock changes from a single oblique shock to a dual shock, which distorts the perpendicular trajectory of the tip clearance vortex but shows no evidence of flow separation that may contribute to stall.

Stall inception and control in a transonic fan, part A: Rotating stall inception

“…by some researchers for both low and high-speed compressors (e.g., [12][13] and [15]). In the recent experiments reported by Weichert and Day [9], however, no forward spillage was observed before and during the emergence of spike.…”

“…Therefore, as emphasized by in [9], "the debate about whether forward spillage occurs before or after stall onset is a topic of current interest which requires more numerical and experimental investigations". Some of the numerical studies reported on stall inception used part-span geometries to reduce the computational cost (e.g., [6][7][8] and [10]), whereas some others performed full-annulus computations (e.g., [11][12][13][14][15][16][17][18]). Hah et al [12] simulated spike-type stall inception in a transonic compressor rotor.…”

Numerical Study of Stall Inception in a Transonic Axial Compressor Rotor Based on the Throttle Model

“…In that case, numerical simulation can be an alternative and complementary way to experimental measurement in analysis of complex flow phenomena. During the past 15 years, Davis and Yao (2006), Chen et al (2008), Yao et al (2010) achieved some valuable results of the flow structure leading to stall by using computational fluid dynamics (CFD) methods.…”

Detailed measurements of the static pressure characteristics around the centrifugal compressor casing wall

“…Studies of the stall inception were always to find the initial moment and inception location as early as possible. The early structure of the stall inception was explained through measuring the static pressure at the initial moment of the stall (Inoue et al, 2000;Chen et al, 2007). The asymmetry of the structure caused the stall inception at the particular blade passage of an axial compressor (Weichert and Day, 2012).…”