Numerical simulation of flow development downstream four perforated plates for flow measurement accuracy

Abstract

Several plates are described in the standard like a flow conditioners. A numerical simulation is done to study the development of the turbulent flow with the presence of four perforated plates. Three of the perforated plates are described in the standard ISO 5167 namely ZANKER, NOVA and NEL plates. The fourth one is a new design and proposed plate. The main goal is a comparative simulation of the four perforated plates to produce the fully developed pipe flow which is a prerequisite for flow measurement accuracy. The flow is analysed in a circular pipe of 100mm diameter. The disturber used for the simulation is a 90° double bend in two perpendicular planes. The geometry of the perforated plates is different with four types of perforations at different diameters. The flow is insured by air at a Reynolds number of 2.5×105. The numerical analysis is conducted by the CFD code Fluent which is based on the resolution of the Navier-Stokes equations with k-ε like turbulence model. The parameter discussed in this study is the velocity. The results show the effectiveness of perforated plates to obtain the fully developed pipe flow at length z/D=20 downstream the disturbers. Downstream this station the contour seems to reach the fully developed pipe flow like at station z/D=100 where the flow is supposed fully developed, and don't exhibit any instabilities of the velocity contour. Contrary, in the stations upstream we found instability of the flow structure. From some stations we show how much the turbulent mixing downstream the perforated plates is important to reach the fully developed pipe flow. The effectiveness of CFD code Fluent to predict flow development in different installations is done where good predictions are presented.