刷式密封传热特性的数值研究

Numerical study on heat transfer characteristics of brush seal

刷式密封在密封过程中会产生的大量摩擦热,影响到其密封性能,针对这一问题,采用数值分析的方法,研究了进出口静压比与背板结构对刷式密封传热特性的影响规律。首先,采用ANSYS软件建立了刷式密封的三维切片热分析模型,通过与实验数据对比验证了该模型的合理性;然后,研究了进出口静压比对刷式密封泄漏量以及刷式密封最高温度的影响,分析了刷式密封的压力场与流场分布情况;最后,在热分析基础上,对刷式密封温度场的分布情况进行了模拟分析,通过改变背板平衡腔的腔体形状、背板平衡腔体深度和下游保护高度,研究了背板结构对刷式密封温度场的影响规律。研究结果表明:随着进出口静压比的增加,刷式密封泄漏量以及刷式密封最高温度变化趋势逐渐变缓;平衡腔的腔体形状改变对刷式密封最高温度的影响有限;刷式密封最高温度随平衡腔体深度的增大而下降,下降趋势变缓;当下游保护高度低于1.2 mm时,随着下游保护高度的减小,最高温度出现的位置由末排刷丝尖端向前排转移,其数值大小呈指数规律上升。

Aiming at the problem of the large amount of frictional heat generated during the sealing process of the brush seal will affect its sealing performance,the influence of the static pressure ratio of the inlet and outlet and the structure of the back plate on the heat transfer characteristics of the brush seal was numerically studied.Firstly,a three-dimensional thermal analysis model of brush seal was established by ANSYS software,and the rationality of the model was verified by comparing with experimental data.Then,the influence of inlet and outlet static pressure ratio on the leakage of brush seal and the maximum temperature of brush seal was studied,and the distribution of pressure field and flow field of brush seal was analyzed.Finally,on the basis of thermal analysis,the distribution of the temperature field of the brush seal was simulated and analyzed.By changing the cavity shape,the depth and the downstream protection height of the balance cavity of the back plate,the influence law of the structure of the back plate on the temperature field of the brush seal was studied.The results show that with the increase of the inlet and outlet static pressure ratio,the leakage’s and the maximum temperature’s change trend of the brush seal gradually become slow down.The change of the shape of balance cavity has a limited impact on the maximum temperature of the brush seal.The maximum temperature of the brush seal increases with the depth of the balance cavity increases,and the downward trend becomes slower.When the downstream protection height lower than 1.2 mm,with the downstream protection height decreases,the position of the highest temperature will shift from the tip of the last row of bristles to the front rows,and the value of it increases exponentially.