NUMERICAL SIMULATION AND EXPERIMENTAL VALIDATION OF THE SWIRLING TURBULENT AIR FLOW AND MIXING PROCESSES

Abstract

The work reported in this article investigates the influences of inlet boundary conditions on the precombustion chamber internal flow patterns, validated by experimental data. An axial fixed-vane swirling diffuser with 12 vanes of declining angle 20° is used for the primary air flow. For the swirling air flow inlet boundary condition specifications, two methods are compared employing the standard κ–ϵ turbulence model. The conventional method is to specify the inlet velocities based on totally constant axial and tangential momentum fluxes. For the new method, the whole simulation domain is extended to the supply duct, and detailed air flows between the supply swirling diffuser and precombustion chamber are linked using the multigrid technique. Comparisons with experimental data reveal that the new method can more accurately predict turbulent air flows and mixing processes near the swirling diffuser, and consequently more accurately predict the size of the recirculation zone, and farther downstream velocities and air jet mass fractions.

This project (project number PolyU 5028/00E) was financially supported by the Research Grants Committee of the Hong Kong SAR government. The authors also wish to thank Prof. Yao Qiang of Tsinghua University for his help in obtaining the dimensions of the swirling vanes.