Aerodynamic Properties of Screens and Fabrics

General rules for the pressure loss of flow across wire screens and simple fabrics are devired herein from the available test data. At higher Reynolds numbers the results obtained agree satisfactorily with the Borda-Carnot theory, which considers the dynamic losses to be due to a sudden expansion of the cross section behind the openings of an obstacle. On the other hand, at very low Reynolds numbers the pressure loss seems to be proportional to the velocity, corresponding to the Hagen- Poiseuille kind of flow. In the intermediate range of the Reynolds number the loss coefficient is found by statistical analysis to be a function of this number and the solidity ratio of the material.