Experiment on discharge characteristics of straight-through labyrinth

Experimental investigation was conducted on the discharge characteristics of the straight-through labyrinth, which was applied widely in aero-engines, under different configurations and operating parameters. Influences on the nominal discharge coefficients of the inclination angle, the clearance of the labyrinth pins and the revolving speed of the shaft were considered. Discharge flow rate and pressures at the entrance and the exit of the labyrinth were measured, and then nominal discharge coefficients and a correction equation were acquired. Moreover, comparisons of experiment data with data calculated from the classical correction equation were done. The results show that nominal discharge coefficients increase with the rising ratio of the inlet total pressure and the outlet pressure, and then tend to a certain constant for each configuration at each operating point. However, they decrease with the decreasing inclination angel and clearance of the through labyrinth in this study. Also the optimum value of inclination angel is in a range of 45°~60°. For the shaft revolving speed of the labyrinth disc, it works complicatedly, and nominal discharge coefficients decrease with its increase clearly.