Numerical Investigation of New Design of the Etoile Flow Straightener

Flow metering of industrial fluids remains the concern of several researchers and exporting countries of gas and oil in the world. It is in this context that a vast numerical investigation is done in our laboratory of Industrial Fluids Measurements and Applications (FIMA). This article examines numerically a new design of the Etoile flow straightener which is described by the standard ISO 5167. This new design consists in removing the central part of the Etoile which, according to researchers, leads to a very high level of turbulence. Our intervention relates to the development and the establishment of the flow parameters downstream the Etoile with and without central part. 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 100%, 50% and 30% open. The flow parameters examined are velocity profile, turbulence intensity profile, and the fluid gyration angle. The code CFD Fluent is used for this simulation. The results obtained are compared according to directives of the standard ISO 5167. The results obtained show that for the valve settings 30% and 50% open, upstream the Etoile, we have a high turbulence level and a velocity profile with recirculation zones more significant for the valve 30% open than for the valve 50% open. It is also noted that the valve develop very high fluid gyration angle apart from the standard values. The flow behavior downstream the central part of Etoile described by the ISO 5167 is well simulated with the valve open at 100%, with a deficit of flow and a very high degree of turbulence. At this stage for the two designs, the noticed results seem so identical beyond a certain stations downstream the Etoile.