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Journal of Zhejiang University SCIENCE A
ISSN 1673-565X(Print), 1862-1775(Online), Monthly
2016 Vol.17 No.12 P.947-960
Investigation of high-speed rubbing behavior of labyrinth-honeycomb seal for turbine engine application
Abstract: The labyrinth-honeycomb seal has been widely used in gas turbine engines as an abradable gas path seal to protect the rotor from wear and damage in rubbing interaction. It usually works with a stepped labyrinth because the knife-edged tips could produce a special dynamic sealing system, and then the minimum clearance is possible between the rotor and stationary component. To investigate the high-speed rubbing behavior between a Hastelloy-X honeycomb material and a GH4169 double stepped labyrinth, nine rubbing tests were conducted using a high-speed abrasion test rig while the blade tip speed varied from 150 to 450 m/s, and the incursion rate from 120 to 360 μm/s. The abradability of honeycomb made from Hastelloy-X was fully verified by analyzing the visual rubbing observations, rubbing forces, and impact acceleration. It is shown that compression deformation happens to the honeycomb material during the rubbing process with the labyrinth blade except for a simple cutting mechanism, which is mainly affected by the parameter of incursion rate. Thermal ablation and oxidation were the main damage occurring on the labyrinth tip and appeared more obviously at a higher blade tip speed. Rubbing forces and impact acceleration were obtained from a piezoelectric dynamometer and acceleration sensor during the rubbing process. At a blade tip speed of 300 m/s and incursion rate of 360 μm/s, radial and tangential forces show their maximum values of 716 N and 871 N, respectively. The peak value of acceleration presents 341g with the highest blade tip speed of 450 m/s and the highest incursion rate of 360 μm/s. All testing results provide a great deal of effective information on high-speed rubbing behavior for the abradablility evaluation of a honeycomb.
Key words: Labyrinth-honeycomb seal, Aeroengine shrouded turbine blade, Abradability, Rubbing mechanism, Rubbing interaction
创新点：1. 成功研制了模拟封严材料高速碰磨行为的可磨耗试验机，最高叶尖线速度可达520 m/s；2. 进行了不同试验条件下的高速碰磨试验，验证了蜂窝材料的可磨耗性能；3. 通过高速碰磨试验，掌握篦齿叶片和金属蜂窝的磨耗机理；4. 获得了高速碰摩力和冲击加速度数据，对应用具有指导作用。
方法：1. 研制高速可磨耗试验机；径向进给系统驱动封严试样主动与高速旋转的模拟叶片接触并发生高速碰磨作用；试验机可模拟的最高叶尖线速度为520 m/s，进给速率为5~1000 μm/s。2. 在可磨耗试验机上进行不同叶尖线速度和进给速率条件下的高速碰磨试验，通过对试验现象以及试验后金属蜂窝和篦齿叶片的磨损形貌进行分析，了解高速碰磨过程中的磨损机理。3. 通过三向测力传感器对试验中的高速碰磨力进行测量，分析碰摩力的变化规律。4. 通过加速度传感器测量瞬时冲击响应，了解冲击作用的大小。
结论：1. 高速碰磨时，金属蜂窝会发生切削和挤压变形，进给速率对挤压变形具有重要影响。2. 高速碰磨 时篦齿与蜂窝的接触区域会产生摩擦火花，导致篦齿叶尖发生烧蚀和氧化，摩擦热的聚集会导致蜂窝材料在被切削时发生涂抹，同时伴随有蜂窝材料向篦齿叶尖的转移。3. 随着碰磨时间的延长，摩擦热逐渐增多，且在高叶尖线速度条件下更加明显。4. 测试到的碰摩力曲线可以分为四个典型阶段：碰磨前、碰磨中、停留和退出；试验测试到的最大径向和切向碰摩力分别为716 N和871 N，不会对转子部件造成损坏。5. 在最大叶尖线速度和最大进给速率参数下测得的冲击加速度最大，约为341g。
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DOI:
10.1631/jzus.A1600367
CLC number:
TG115.5; V250
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On-line Access:
2016-12-06
Received:
2016-05-10
Revision Accepted:
2016-08-09
Crosschecked:
2016-11-10