考虑转轴伸长效应的刷式密封泄漏流动和摩擦传热特性

Leakage Flow and Frictional Heat Transfer Characteristics of Brush Seals Considering Shaft Elongation Effects

为研究转轴伸长效应对刷式密封的泄漏量与摩擦传热特性的影响,建立了考虑转轴伸长效应的刷式密封流热固模型的泄漏流动和摩擦传热特性数值模型。通过数值求解三维雷诺时均(RANS)方程和多孔介质模型局部非热平衡能量方程的方法研究了刷式密封流动传热特性;采用有限元法方法,研究刷式密封非线性接触和转轴伸长特性,研究了转速、压比等不同工况和前、后夹板与转轴径向间距等几何参数对刷式密封的泄漏流动、摩擦传热特性的影响规律。研究结果表明:相比于不考虑转轴伸长,考虑转轴伸长时刷式密封泄漏量减小,刷丝束最高温度明显升高;刷式密封泄漏量随压比的增大,前、后夹板与转轴间隙的增大而增大,随转速的增大而减小;随着压比增大,刷式密封最高温度越高,但刷丝束平均温度降低。随着转速增大,刷式密封最高温度显著提高,转速从1000 r·min^(-1)增长到4000 r·min^(-1)时,刷丝束最高温度增加了约86%。随着前、后夹板与转轴面的间距增大,刷丝束最高温度先升高、后降低。研究为刷式密封运行工况下的流动传热特性分析提供了一定的参考。

In order to investigate the impact of shaft elongation effects on the leakage and friction heat transfer characteristics of brush seals,a numerical model for the leakage flow and friction heat transfer characteristics of brush seals considering shaft elongation effects is established.The flow and heat transfer characteristics of brush seals are analyzed by numerically solving the three-dimensional Reynolds-averaged Navier-Stokes(RANS)equations and the local non-thermal equilibrium energy equation of the porous media model.The nonlinear contact and shaft elongation characteristics of brush seals are examined using the finite element method to explore the effects of different operating conditions such as rotational speed,pressure ratio,geometric parameters like the radial gap between the front and rear plates and the shaft on the leakage flow and frictional heat transfer characteristics of brush seals.The results indicate that when considering shaft elongation effects,the leakage flow of brush seals decreases,while the maximum temperature of the brush bristle bundle notably increases compared to cases where shaft elongation effects are not considered.The leakage flow of brush seals increases with increasing pressure ratio and the radial gap between the front and rear plates and the shaft,but decreases with increasing rotational speed.As the pressure ratio increases,the maximum temperature of the brush seal also increases,but the average temperature of the brush bristle bundle decreases.With increasing rotational speed,the maximum temperature of the brush seal significantly increases,with the maximum temperature of the brush bristle bundle increasing by approximately 86%as the rotational speed increases from 1000 r·min^(-1)to 4000 r·min^(-1).As the radial gap between the front and rear plates and the shaft increases,the maximum temperature of the brush bristle bundle first increases and then decreases.This research offers valuable insights for analyzing the flow and heat transfer characteristics of brush seals under operating conditions.