Numerical characteristics of a centrifugal compressor with a low flow coefficient

Abstract

The study presents the simulation results of the viscid gas flow in low flow coefficient centrifugal compressor stages. The problem is solved in a stationary formulation using the Ansys CFX software package. The numerical simulation is carried out on three ultrahigh-pressure model stages; two stages have blades of the classical type impeller and one stage is of the bodily type. The value of the conditional flow coefficient is 0.0063 to 0.015. As part of the study, block-structured design meshes are used for all gas channel elements, with their total number being equaled as 13–15 million. During the calculations a numerical characteristic was validated with the results of tests carried out at the Department of Compressor, Vacuum and Refrigeration Engineering of Peter the Great St. Petersburg Polytechnic University. With an increase of inlet pressure as a result of a numerical study, it was found that for a given mathematical model the disk friction and leakage coefficient (1 + βfr + βlk) is overestimated. The analysis of flow in labyrinth seals has shown an increase of total temperature near the discs by 30–50 °С, nevertheless this fact did not influence gas parameters in the behind-the-rotor section. The calculation data obtained with finer design mesh (the first near-wall cell was 0.001 mm) is identical to those obtained with the first near-wall cell 0.01 mm mesh.

Research of a Spatial Flow of a Low-Flow Stage of a Svd-22 Centrifugal Compressor by Computational Fluid Dynamics Methods Using Super-Computer Technologies

“…Additionally it is necessary to apply methods of calculating the properties of real gases [8][9][10]. In particular, there are studies by CFD methods of low-flow stages of a centrifugal compressor [11][12][13][14][15][16]. The flow path of the stage, the sketch of which is shown in The aim of this work is to obtain the fluid dynamics characteristics of the low-flow stage SVD-22 by modeling the flow of a viscous gas in the flow path using computational fluid dynamics methods and comparing the obtained characteristics with the results obtained as a result of a full-scale experiment -verification of the calculation data.…”

Verification and Validation of CFD Modeling for Low-Flow-Coefficient Centrifugal Compressor Stages

“…Numerical methods must be verified and validated before being applied [5]. The largest number of works are concentrated on medium-and high-flow stages with 3D impellers, while relatively few works are concentrated on the verification and validation of numerical calculations with experimental data in stages with low-flow coefficients [6][7][8][9][10][11][12][13]. The estimation of the modeling uncertainty for low-flow stages in the available literature is presented in Table 1.…”

“…Large uncertainty in [8] is due to unaccounted gaps and seals. The full stages are presented in four works [10][11][12][13]. In [10], an increased uncertainty of more than 10% for the pressure coefficient is obtained, along with up to 3% for the rest.…”