刷式密封流动传热特性数值方法

开展了刷式密封流动传热特性数值方法研究，分别建立了刷式密封多孔介质、稳态实体与瞬态流固热耦合求解模型，设计搭建了刷式密封泄漏流动特性实验装置，在实验验证数值方法准确性基础上，对比分析了3种数值方法的差异性，研究了刷式密封流动传热特性，揭示了刷式密封的封严与传热机理。研究结果表明:在研究工况下，刷式密封多孔介质、稳态实体、瞬态流固热耦合模型泄漏量计算值与实验值的对比误差分别为9.8%~17.1%、8.1%~10%、6.92%~9.01%。刷式密封多孔介质模型计算速度较快，但需通过实验修正孔隙率，湍流模型对稳态实体模型流动传热特性结果影响较大，瞬态流固热耦合模型考虑了流场、刷丝及摩擦热三者间相互耦合作用，计算精度较高，但所需计算时间较长；同一压比下刷丝束温度从上游至下游逐渐增加，刷丝束最高温度随压比的增加而增大。气流流经刷丝间隙形成的节流效应致使泄漏气流能量耗散是刷式密封封严的主要原因，泄漏气流与刷丝表面间的对流换热是刷式密封摩擦热耗散的主要形式。 

Numerical method of flow and heat transfer characteristics of brush seals

Numerical methods for the flow and heat transfer characteristics of brush seals were studied，and the porous media，steady-state solid and transient fluid-solid-heat coupling models of brush seals were established respectively.An experimental device for leakage flow characteristics of brush seals was designed and built.On the basis of verifying the accuracy of the numerical method by experiment，the differences of three numerical methods were compared and analyzed，the flow and heat transfer characteristics of brush seals were studied.The sealing and heat transfer mechanism of brush seals was revealed.The research results showed that:under the working conditions，the error between the leakage calculated by brush seals porous media，steady-state solid and transient fluid-solid-heat coupling model and the experimental values was 9.8%-17.1%，8.1%-10%，6.92%-9.01%，respectively.The calculation speed of brush seals porous media model was faster，but experiment was required for correction of the porosity；the turbulence model had great influence on the flow and heat transfer characteristics of steady-state solid model；the transient fluid-solid-heat coupling model considered the interaction among flow，bristle and frictional heat，and the calculation accuracy was high，but the calculation time was longer.At the same pressure ratio，the temperature of bristle pack gradually increased from upstream to downstream，and the highest temperature of bristle pack increased with the increase of pressure ratio.The main reason for sealing of brush seals was attributable to the throttle effect of air flow through brush wire gap resulting in energy dissipation of leakage air flow，and the convective heat transfer between the leakage gas flow and the brush wire surface was the main form of friction heat dissipation of brush seals.