新型转子含叶栅的迷宫密封流场特性数值研究

Numerical study on flow field characteristics of a new labyrinth seal with cascade in rotor

针对传统迷宫密封泄漏量较大的问题,借鉴叶栅吹风效应,提出了一种新型转子含叶栅的迷宫密封结构。分析了新型密封结构的工作原理,建立了三维传统密封与新型密封数值求解模型。在验证求解模型准确的基础上,研究了转子转动方向、转速和压比等因素对传统密封与新型密封泄漏量的影响规律,分析了传统密封与新型密封的流场特性与泄漏特性,揭示了新型密封的封严机理。研究结果表明,传统迷宫密封在转子正反转的不同状态下泄漏量保持不变,而新型迷宫密封的泄漏量在转子正转时相较于转子不转下降了6%。在转子反转时相较于转子不转增加了6%;在转速低于5000r/min时,随着转子转速的增加,传统迷宫密封的泄漏量几乎不变,而新型迷宫密封的泄漏量下降了10%~15%;在转速高于5000r/min时,随着转子转速的增加,传统迷宫密封的泄漏量下降了2%~5%,新型迷宫密封的泄漏量下降了15%~25%。随着压比的增加,传统迷宫密封和新型迷宫密封的泄漏量都增大,但新型迷宫密封的泄漏量相对于传统迷宫密封下降了15%以上。与传统迷宫密封相比,新型迷宫密封由于转子上含有叶栅,导致转子转动时会在叶栅上形成高低压区,从而形成一股与泄漏气体方向相反的气流,起到增加阻力抑制泄漏的作用。提出的新型密封结构的封严特性优于传统迷宫密封。

In view of blowing effect of cascade,a new type of labyrinth seal structure with cascade was proposed to solve the problem of large leakage in traditional labyrinth seal.In this paper,the working principle of the new sealing structure was analyzed.Numerical solution models of both three-dimensional traditional sealing and new sealing were established.On the basis of verifying accuracy of the model,the effects of rotor rotation direction,rotational speed and pressure ratio on the leakage rate of both traditional and new labyrinth seals were studied.The flow field characteristics and leakage characteristics of the seals were further analyzed.Sealing mechanism of the new seal was revealed.The results showed that the leakage of the traditional labyrinth seal still remained unchanged when the rotation direction of the rotor was different.The leakage of the new labyrinth seal decreased by 6%when the rotor rotated in the forward direction compared to nonrotating rotor,while it increased by 6%when the rotor rotated in the afterward direction.At the rotor speed below 5000r/min,the leakage of the traditional labyrinth seal almost unchanged with the increase of the speed.However the leakage of the new labyrinth seal decreased by 10%to 15%.When the speed was higher than 5000r/min,the leakage of the traditional labyrinth seal decreased by 2%to 5%,and the one of the new labyrinth seal decreased by 15%to 25%.With increasing pressure ratio,the leakage of both the traditional and new seal increased.The leakage of new seal decreased by more than 15%compared to the traditional labyrinth seal.A high and low pressure region around the cascade forms when the rotor rotates due to the present of the cascade in rotor,which causes the formation of an air flow along the opposite direction.The flow can increase resistance and suppress leaks.In this paper,a new labyrinth seal structure of rotor with cascade was presented.The sealing characteristic of the new seal structure is better than that of traditional labyrinth seal.