On the prediction of pressure losses in complex flow scenarios using CFD

摘要

The applicability of open-source CFD software to obtain pressure loss predictions in complex tunnel geometries is investigated. Beginning the simple validation case, of a straight pipe, the friction factor calculated using CFD results is within 2% of the empirical value. Then for a 90° sharp bend, the pressure loss factor predicted using CFD is within 11.3% of values from references [1], [2] and [3]. For abrupt expansions with multiple area ratios the error in the CFD compared to the analytical value is between 6.8% and 18.3%. Considering multiple junctions in quick succession, it is shown that it is necessary to account for the flow interaction between the junctions to avoid errors in pressure loss calculations. For varying distances between two 90° mitre bends, CFD predicts the combined pressure loss factor to within 15% of empirical data. Finally, the validated methodology is applied to a complex case of industrial interest for flow through a tunnel ventilation fan plenum in a station.