旋转盘腔盘缘热流密度的敏感性分析

Sensibility Analysis of the Heat Flux in the Rotating Cavity

关键词:  适航  旋转盘腔  基比切夫数  冷却效果  敏感性分析

Key words:  Airworthiness  Rotating cavity  Chebyshev number  Cooling effect  Sensibility analysis

摘要:

为保证涡轮盘满足适航规章的安全性要求,采用单向流固耦合数值方法,研究了转静系旋转盘腔以基比切夫数表示的盘缘加热热流密度的变化对冷却效果的影响,并依据旋转盘腔冷却问题的工程评价体系对旋转盘腔的冷却效果进行评价。研究结果表明:基比切夫数的变化对于旋转盘腔的流动结构和流动阻力基本没有影响,对盘面的换热效果影响也较微弱,仅引起转盘迎风面热流密度和温度的改变。同时,温度分布的改变导致了与温度梯度紧密相关的热应力水平发生变化。随着热流密度的增加,转盘整体应力水平上升,并且盘缘附近区域的等效应力提高的幅度大于中心区域。当基比切夫数高于临界值后,最大等效应力值从转盘中心转移到盘缘。基比切夫数的变化能够从部件承受能力和实际使用载荷两方面对涡轮盘的失效概率产生较大影响,因此,在涡轮盘腔的设计阶段,需要考虑基比切夫数对涡轮盘安全性的影响。 

Abstract:

Fluid-Structure-Interaction numerical method was applied to investigate the effects of the heat flux, which is presented as Chebyshev number, on the cooling of the rotating cavity. The cooling effect was also evaluated in accordance with an engineering evaluation system, which includes resistance evaluation, heat transfer evaluation and stress distribution evaluation, in order to ensure the safety of the turbine disk. The results show that the heat flux and the temperature distribution of the disk exhibited the influence of the variation of the heat flux on the outer rim of the disk which has no effect on the fluid structure of the rotating cavity and the flow resistance. Meanwhile, the thermal stress related to the temperature gradient can be affected. The stress level of the disk rises as increasing the Chebyshev number. The stress on the outer rim of the disk grows greater than it on the inner rim. The peak stress transfers from the centre to the disk rim while the Chebyshev number exceeds the critical value. Therefore, the change of the Chebyshev number has an effect on the failure probability of the turbine disk from both the material affordability and the working stress.