考虑发动机性能退化的涡轮叶尖间隙预估方法研究

Method of Turbine Tip Clearance Prediction Considering Engine Performance Degradation

关键词:  高压涡轮  叶尖间隙预估  主动间隙控制  涡轮性能退化  热变形

Key words:  High pressure turbine  Tip clearance prediction  Active clearance control  Turbine performance degradation  Thermal deformation

摘要:

针对有主动间隙控制的某型高压涡轮，建立了考虑发动机退化的叶尖间隙预估模型，重点研究了发动机在长期使用、性能退化过程中涡轮前燃气温度和蠕变变形对叶尖间隙的影响。研究中，首先分析了间隙预测中发动机性能退化影响的引入方式，建立了对应的间隙预估流程。随后以某型发动机典型工作历程为对象，对比研究了传统间隙控制方案、考虑发动机性能退化影响两种条件下的涡轮叶尖间隙尺度变化规律，并据此开展了间隙控制策略的优化调整。研究中发现，由于发动机性能的退化，导致涡轮前燃气温度升高，使得机匣、轮盘和叶片的热变形量增大，其中在最大巡航阶段对机匣的影响最大，其伸长量达到了6.914mm，与未退化前相比增大了17%，同时由于发动机的长期使用，叶片和轮盘受蠕变变形影响，导致叶尖间隙的变化。研究结果表明，采用优化后的主动间隙控制方案，各个工况下的叶尖间隙值均控制在合理范围内，尤其在高温起飞阶段，与退化状态下的间隙值相比提高了53%，有效避免了叶片严重碰摩等故障发生。

Abstract:

For a certain type of high pressure turbine with active clearance control， a tip clearance estimation model considering engine degradation is established. The effects of turbine front gas temperature and creep deformation on tip clearance during long-term use and performance degradation of the engine are mainly studied. In the research， the introduction method of performance degradation of engine in gap prediction is analyzed firstly， and the corresponding gap estimation process is established. Subsequently， using the typical working history of an engine as the object， the variation of turbine tip clearance scale in the two conditions of traditional gap control scheme and scheme considering the performance degradation of engine are compared. The optimization of the gap control strategy is carried out accordingly. The study shows that the degradation of engine performance results in the increasing of turbine inlet gas temperature， which increases the thermal deformation of the casing， disc， and blade， especially for the casing. The elongation of the casing reaches 6.914 mm and increases 17% compared with the pre-degraded values. The blade and the disc are also affected by the creep deformation and affects the tip clearance value. Results predict that utilizing the optimized active clearance control scheme， the tip clearance value can be controlled within a reasonable range in various working conditions. Particularly in the high temperature takeoff phase， the value is 53% higher than that in the degraded state. It effectively avoids the occurrence of faults such as severe rubbing of the blades.