FLOW DEVELOPMENT DOWNSTREAM OF TWO SIMPLIFIED AND ONE K-LAB/LAWS FLOW CONDITIONERS - EXPERIMENTS AND CALCULATIONS

摘要

The standard k-8 turbulence model was used to predict the flow in a pipe downstream of 2 obstruction plates having 1 large or 9 small holes, and one 19-hole K-Lab/Laws flow conditioner. Both mean velocity, turbulent kinetic energy, k, and the dissipation rate of turbulent kinetic energy, e, were calculated. From the predictions critical flow characteristics such as reattachment point, length of axial jets, turbulent regions and the distance required for the restablishment of fully developed flow downstream of the different plates are reported. A comparison between measured and simulated results reveal that the numerical model is capable of describing the trends in the flow. But just downstream of the plates, it is more difficult to calculate accurately the flow field of a simple one hole device than a more complex geometry like a 19-hole flow conditioner. It is assumed that the flow structure is largely affected by the turbulence level, which here is inversely proportional with the number of holes in the plates. The higher the turbulence level, the larger is the deviation in the predicted values. From 10D and further downstream, where the turbulence structure was relatively unimportant, the simulations were satisfactory for all plates.