The boundary layer separation from streamlined surfaces and new ways of its prevention in diffusers

Authors

Arkady Zaryankin - Moscow Power Engineering Institute (MPEI, National Research University)
Andrey Rogalev - Moscow Power Engineering Institute (MPEI, National Research University)
Ivan Komarov - Moscow Power Engineering Institute (MPEI, National Research University)
V. Kindra - Moscow Power Engineering Institute (MPEI, National Research University)
S. Osipov - Moscow Power Engineering Institute (MPEI, National Research University)

Abstract

This work provides a detailed analysis of all force conditions acting in the limits of the boundary layer on the moving fluid and gas media, and shows that a value of the transverse gradient of a shear stress δτ/δy, directly on the streamlined surface, is a main condition determining the possibility of attached flow along the streamlined surface in divergent zones. From an analysis of all the forces and their development in the converging flow, an effective way of prevention of the flow separation from streamlined surfaces of the cone-type, ring-type and axial-radial diffusers was developed that provides the flow stabilization in the wide-angle diffusers and multiple reduction of the dynamic load level acting on the walls of the mentioned devices. Results of the CFD-modeling and experimental investigations for flat asymmetric and wide-angle conical diffusers are presented in this paper.