Length Efficiency of the Etoile Flow Straightener: Numerical Experimentation

This article presents a numerical investigation of the development and the establishment of the flow in the presence of the Etoile flow straightener recommended in ISO 5167 (ISO 5167. Measurement of fluid flow by means of orifice plates, nozzles and venture plates inserted in circular cross-section conduits running full, 2003). The objective of this study is to examine the effectiveness length of the Etoile flow straightener, recommended by ISO 5167 with length of two pipe diameters, on the development and the establishment of the flow. The flow is produced by air in a 100mm pipe diameter and 40D of length with a Reynolds number of 2.5×10⁵. The disturbance is a valve maintained at 100% and 50% open. The flow parameters examined are velocity profile, turbulence intensity profile, and the gyration of the fluid. Several measuring stations upstream and downstream of the unit are done. The code CFD Fluent is used for this simulation. The results obtained are compared according to directives of the standard ISO 5167. However, they show that for position valve 100% open the various lengths of the Etoile flow straightener do not present differences for the three flow parameters. On the other hand, for the valve position 50% open, the Etoile flow straightener with 2D length which presents the best performances according the standard.