축류 회전차 익말단 틈새유동에 대한 수치해석 (III) - 회전차 익말단의 누설손실과 효율저하에 대한 평가 -

Numerical Analysis on the Blade Tip Clearance Flow in the Axial Rotor (III) - Evaluation of Tip Leakage Loss and Reduction of Efficiency near Blade Tip Clearance Region of a Rotor -

Leakage vortices fonned near the blade tip cause an increase of total pressure loss near the casing endwall region and as a result, the efficiency of rotor decreases. The reduction of rotor efficiency is related to the size of tip clearance. In this study, the three-dimensional flow fields in an axial flow rotor were calculated with varying tip clearance under various flow rates, and the numerical results were compared with experimental ones. The effects of tip clearance and the of attack on the leakage vortex and overall performance, and the los9 distributions were investigated through numerical calculations. In this study, tip leakage flow rate and total pressure loss due to the tip clearance were evaluated using numerical results and approximate equations were presented to evaluate the reduction of rotor efficiency due to the tip leakage flow.