On investigating the flow through an axisymmetric channel with sudden changes in geometry

Abstract

The paper presents the authors first experience in the complementary use of the CFD and PIV methods for the investigation of a steady flow of an incompressible fluid through a successive sudden contraction (diameters ratio 4:1) and expansion (diameters ratio 1:2). The investigation of this flow was chosen by the authors as a test case for an assessment of the capability of a standard PIV system to make accurate measurements of the 2D velocity field. With this aim in view, in a first step of the study the flow was investigated by numerical simulations using the CFD code FLUENT, in order to map the velocity field and to identify the zones covered by recirculation flow. An experimental set-up was built and PIV investigations were conducted for validating the numerical simulation results. It was observed that there currently exist important technical limitations of the experimental setup in assessing the velocities close to the walls, and implicitly affecting the possibility of validating the results of the numerical simulation. That is why, based on the PIV investigation, at the current stage of the study the authors can only advance qualitative observations and identify possible solutions to upgrade the PIV setup.