迷宫-刷式密封泄漏流动和摩擦传热特性数值研究

Numerical Investigations on Leakage Flow and Frictional Heat Transfer Characteristics of Labyrinth-Brush Seal

关键词:  迷宫-刷式密封  泄漏流动  摩擦传热  热应力  数值模拟

Key words:  Labyrinth-brush seal  Leakage flow  Frictional heat transfer  Thermal stress  Numerical simulation

摘要:

为了探究结构参数和运行工况参数对迷宫-刷式密封泄漏流动和摩擦传热特性的影响规律，采用数值求解三维Reynolds-Averaged Navier-Stokes（RANS）方程耦合有限元分析（FEA）的方法，数值研究了围栏高度h_b，前夹板与转子间隙h_f，转速n和压比R_p对迷宫-刷式密封泄漏流动、温度分布以及转子热应力的作用规律。研究结果表明：刷丝束与转子的摩擦生热使得泄漏流量显著降低；R_p和h_b对接触式迷宫-刷式密封封严性能有着决定性作用。R_p和n升高使得摩擦热流密度和转子最高温升显著增大。h_b增大使得摩擦热流密度和转子最高温升先增大后减小；h_f增大使得摩擦热流密度先略微增大后减小，转子最高温升逐渐减小；转子最高温升随h_b或h_f增大的变化趋势取决于摩擦热流密度增幅和气流冷却作用增强幅度的相对大小。转子最高热应力随R_p和h_b升高而增大，随h_b增大而先增大后减小，随h_f增大而减小。

Abstract:

In order to explore the effects of geometrical parameters and working conditions on the leakage flow and frictional heat transfer characteristics of labyrinth-brush seal， a method of solving the three-dimensional Reynolds-Averaged Navier-Stokes （RANS） equations and coupling with finite element analysis （FEA） is adopted to numerically investigate the influences of fence height （h_b）， clearance between the front plate and the rotor （h_f）， rotational speed （n） and pressure ratio （R_p） on the leakage flow， temperature distribution and rotor thermal stress of a labyrinth-brush seal. The results show that the frictional heat generation between the bristles pack and the rotor significantly reduces the leakage flow rate. R_p and h_b play a decisive role in sealing performance of the interference labyrinth-brush seal. The increasing R_p and n observably increase frictional heat flux and maximum temperature rise of the rotor. The frictional heat flux and the maximum temperature rise of the rotor first increase and then decrease with the increase of the h_b. While due to the increasing h_f， frictional heat flux first slightly increases and then decreases， and maximum temperature rise of the rotor gradually decreases. The change trend of the maximum temperature of the rotor with the increase of the h_b or the h_f depends on the relative magnitude of the increase of frictional heat flux and the increase of air cooling effect. The maximum thermal stress of rotor increases with the increase of R_p and h_b， first increases and then decreases because of the increasing h_b， and decreases with the increase of the h_f.