Leakage of Air through Labyrinth Glands of Staggered Type

A simplified theory is presented for the flow of air through a single orifice or constriction. This theory is then extended to cover the flow of air through a labyrinth gland having several constrictions of equal area. Experiments are made over a wide range of pressure ratios to determine the coefficient of discharge for a single annular constriction having a small clearance. It is found that the curve has the same general characteristics as that for a circular sharp-edged orifice. The discharge coefficients are then used to calculate the critical ratio of inlet pressure to outlet pressure for a labyrinth gland. The results obtained agree well with experiments on a stationary labyrinth gland of the staggered type in which the number of constrictions may be varied from one to fourteen.The theoretical pressure distribution is derived and compared with experimental values under conditions where the pressure drop across the last constriction is either less or greater than the critical value. Finally, the coef...