Experimental Study And Numericalanalysis On The Discharge Coefficient Of Rotating Orifices

Orifices as the important throttling components in aircraft engine air system, which have an great effect on the flux control, are widely posted on the structures such as turbine disks, drums, shafts and so on. Based on the orifice coefficient of aircraft engine air system, This article adopted the method of experimental study and numerical simulation to research the change rules of the discharge coefficient of rotating orifices which were based on the factors such as diameter-to-length, inclination angle, chamfering and pressure ratio in order to present technical support for the orifice design of aircraft engine air system.The article designed the experimental rig of the rotating orifice discharge coefficient. It improved the structure of labyrinth seal and rorating components to settle the problem that leakage could not be measured in previous studies, The establishment of measurement method of rotating orifice discharge coefficient helped accomplish the accurate measurement of labyrinth leakage, thereby improving the measurement error of rotating orifice discharge coefficient.Based on the experimental rig, the article researched the different geometric parameters(hole length-to-diameter ratio, inclination angle, chamfer) and flow parameters(pressure ratio) and used the numerical simulation to reveal the mechanism. In the range of parameters, we got the following important conclusions: the pressure ratio had no effect on discharge coefficient in the same Ro; For the axial hole, the discharge coefficient increased with the ratio of length-to-diameter increased, and with the length-to-diameter increasing orifice discharge coefficient was reduced, when the length-todiameter ratio came to a certain extent, disharge coefficient was constant; For the radial holes, when the length-to-diameter ratio l/d≤0.85, the length-to-diameter ratio almost had no effect on the discharge coefficient, when l/d>0.85, discharge coefficient increased slightly; Axial orifice discharge coefficient decreased with increasing inclination angle, and the larger the rotation number was, the smaller the coefficient declines was; For the radial hole, the maximum of discharge coefficient were achieved when the incident angle was closed to i=0, and whether the increase of incident angle was increased or reduced, discharge coefficient would be decreased. while the incident angle of i>0, in the same incident angle, the great discharge coefficient corresponded to the large incident angle, When the incident angle i<0, the result was on the contrary; Compared to the no-chamfer hole, chamfering made discharge coefficient improve significantly, with the increase of c/d, discharge coefficient increased gradually, but the increase ratio decreased.