Methodology of calculation and verification of vaneless diffusers test results in a virtual wind tunnel

Computational gas dynamics methods seem to be a suitable tool for calculating gas-dynamic characteristics of a designed compressor. Scientific and research laboratory “Gas dynamics of turbomachines”, SPbPU successfully applies the results of generalization of CFD calculations to creation of mathematical models of flow path elements. In particular, a model of vaneless diffusers with relative widths of 0.014-0.100 was created earlier in this way. This research opens the way to extending the modeling range to a smaller relative width of 0.006. Before application of CFD calculations, it is necessary to develop a method of setting up calculations and verifying them. The paper presents a calculation method, namely: the choice of the grid (by varying the number of cells), the turbulence model, the sector of calculation, and ways of setting boundary conditions. Verification was carried out by comparison with experimental data by C. Rodgers for diffusers, which were tested together with impellers. CFD calculations were compared with W. Jansen's vaneless diffuser wind tunnel tests with a uniform flow at the inlet. The difference is explained by the fact that the described experiment was carried out at a lower velocity coefficient.