Experimental study and structural improvement of leakage characteristics of variable stator vane pivot

There is a gap leakage between the variable stator vane pivot of the compressor and the casing, which has a direct impact on the efficiency of the compressor. To obtain the leakage characteristics of the pivot gap, a high-pressure ratio pivot leakage experimental platform was established. Using flow control and pressure loss methods, the air leakage rates under various gaps and inlet-outlet pressure ratios were measured, and the effects of the mating condition between the pivot and casing, as well as axial and radial gaps, on the leakage rate were analyzed. Experimental results indicated that increases in pressure ratio, axial, and radial gaps led to an increase in both the leakage rate and the flow coefficient; under operating conditions with a pressure ratio of 3.3, the leakage rate in a radial contact state was reduced by 86.54% compared with a 0.01 mm gap state. Eccentricity of the pivot can lead to an increase in leakage rate, whereas tilt can decrease it. To reduce leakage, simulation analysis on the flow characteristics of the leakage was conducted, and a sealing structure using simple bushings or splined bushings for cavity filling was proposed. The simulation results indicated that under operating conditions with a pressure ratio of 3.3, the leakage rate decreased by approximately 40.04% with the addition of simple bushings, and by approximately 31.8% with the addition of splined bushings.