汽轮机叶顶间隙内非定常流动的数值分析

为了分析叶顶间隙泄漏涡的影响范围、运行轨迹和强度的变化规律，以某汽轮机高压级为研究对象，采用SSTκ-ω湍流模型，应用PISO算法对叶项间隙内的非定常流动进行了数值模拟．结果表明：叶顶间隙泄漏流是有规律的周期性的非定常流动，泄漏涡的影响范围、运行轨迹和强度随时间和叶顶间隙的变化而变化；泄漏流对主流的影响呈现出从弱到强、再从强到弱的周期性变化规律；叶顶间隙泄漏涡在丁／4时刻的强度和影响范围均达到最大，在T／2时刻，静叶脱落涡和动叶吸力面前部的泄漏涡混合形成新的涡系，而动叶吸力面后部的泄漏涡却与其边界层的脱涡混合，离开吸力面．

Numerical Analysis on Unsteady Flow in Blade Tip Clearance of Steam Turbines

Taking the blade tip clearance in high-pressure stage of steam turbine as an object of study, numerical simulation was performed on unsteady leakage flow in the clearance using κ-ω sst turbulence model and PISO algorithm, so as to analyze the incidence, trajectory and intensity of the leakage vortex. Results show that the tip leakage flow is of the cyclic and unsteady type; the incidence, trajectory and intensity of the leakage vortex vary with the time and tip clearance height; the effect of tip leakage flow on main stream exhibits a regular variation, from weak to strong, and then from strong to weak; the strength and inci- dence of the leakage vortex reach their maximums at T/4 ; and at T/2, the tail-edge shedding vortex of sta- tor blade mix with the leakage vortex in the front of suction surface of rotor blade, creating a new vortex system, while the leakage vortex in the rear of suction surface of rotor blade mix with the separation vortex at its boundary, leaving the suction surface of rotor blade.