基于多孔介质局部非热平衡方法的刷式密封耦合传热特性

建立了刷式密封流动传热与摩擦接触的多物理场耦合分析的计算模型.推导了描述刷式密封在局部非热平衡条件下耦合传热过程的双能量方程,该方程既考虑了刷丝与气流的对流换热,同时也考虑了刷丝束内导热过程的各向异性.采用所建立的耦合计算模型数值预测了刷式密封在不同压比和转速下的温度分布.结果表明:刷式密封的摩擦热效应使刷丝与转子相接触的附近区域形成局部高温,刷丝的高温区域主要集中在围栏高度以下;泄漏气流与刷丝间强烈的对流换热使刷丝的温度分布和气流的温度分布非常相近;刷丝的最高温度随压比增大而升高,但围栏高度以下区域的平均温度随压比增大而降低;刷丝的最高温度和围栏高度以下区域的平均温度均随转速升高而升高;摩擦热效应引起的泄漏气流的温升效应使刷式密封泄漏量随转速升高而减小.

Conjugate heat transfer characteristics of brush seal based on local thermal non-equilibrium porous medium approach

Computational model was developed for multi-physics coupling simulation of the flowing, heat transfer, frictional contact of the brush seal. A dual-energy equation was proposed to describe the conjugate heat transfer in the brush seal under local thermal non-equilibrium condition. Both the heat convection between the bristle and airflow and the anisotropy of heat conduction in the bristle pack were considered in the dual-energy equation. The temperature distributions of brush seal were numerically predicted using the developed computational model at various pressure ratios and rotational speeds. Results show that a local high temperature region is formed around the bristle-rotor contact area due to frictional heat effect of brush seal. The high temperature region of bristles is mainly located under fence height. The temperature distribution of airflow is similar to that of bristles due to strong heat convection between leakage airflow and bristles. The maximum temperature of bristles increases with the increasing pressure ratio. The average temperature under fence height region of bristles decreases with the increasing pressure ratio. The maximum temperature and average temperature under fence height region of bristles increase with the increasing rotational speed. The temperature rise effect of leakage airflow arising from frictional heat effect makes the leakage rate of brush seal decrease with the increasing rotational speed.