Containment of high-speed rotating disk fragments

Disk burst accidents sometimes happen in aeroengines.To avoid tragic consequences,aeroengine casings must have sufficient containment capability.Experiments and simulations need to be conducted to study the impact,distortion,and perforation caused by disk burst and which may give important clues to potential failure mechanisms.This paper presents some containment tests of high-speed rotating disk fragments,in which the original disks were burst into three equal fragments within a predetermined rotating speed range.The failure modes of the containment casing varied significantly with the thickness of the containment casing.Shearing,tearing,tensile fracture,and large plastic stretching deformation occurred in a thin-walled containment casing,while a thick-walled casing could contain disk fragments and withstand large plastic deformation.Numerical simulations were carried out to study the impact process and failure modes further.Good agreement was found between the results of the simulations and the tests.

Simulation methodology development for rotating blade containment analysis

An experimental and numerical investigation on the aeroengine blade/case containment analysis is presented. Blade out containment capability analysis is an essential step in the new aeroengine design, but containment tests are time-consuming and incur significant costs; thus, developing a short-period and low-cost numerical method is warranted. Using explicit nonlinear dynamic finite element analysis software, the present study numerically investigated the high-speed impact process for simulated blade containment tests which were carried out on high-speed spin testing facility. A number of simulations were conducted using finite element models with different mesh sizes and different values of both the contact penalty factor and the friction coefficient. Detailed comparisons between the experimental and numerical results reveal that the mesh size and the friction coefficient have a considerable impact on the results produced. It is shown that a finer mesh will predict lower containment capability of the case, which is closer to the test data. A larger value of the friction coefficient also predicts lower containment capability. However, the contact penalty factor has little effect on the simulation results if it is large enough to avoid false penetration.

Investigation of high-speed abrasion behavior of an abradable seal rubber in aero-engine fan application

Abradable seal rubber has been widely used in aero-engine fans to improve their efficiency by reducing the clearance between rotating and stationary components. To investigate the high-speed scraping behavior between a vulcanized silicone rubber and a Ti-6Al-4V fan blade and evaluate the abradable performance of seal rubber, abrasion tests were conducted at a blade tip velocity of 50–300 m/s with an incursion rate of 100 lm/s. The influences of the blade tip velocity on the wear mechanism and interaction forces were specially analyzed. It is shown that abrasive wear and pattern wear are the predominant wear mechanisms, and pattern wear can be seen as the emergence and propagation of cracks. With an increase of the blade tip velocity, both of the final incursion depth and wear mass loss of seal rubber exhibit growth trends. The gradual changes of rubbing forces with an increase of rubbing time are the characteristic of abrasive wear, and force curves with unstable mutations are a reflection of pattern wear. At a constant incursion rate of 100 lm/s, the maximum values of interaction forces decrease first and then grow with an increase of the blade tip velocity, and the blade tip velocity of 150 m/s becomes the cut-off point between abrasive wear and pattern wear.

Containment ability and groove depth design of U type protection ring

High-energy rotor uncontained failure can cause catastrophic damage effects to aircraft systems if not addressed in design. In this paper, numerical simulations of three high-energy rotor disk fragments impacting on U type protection rings are carried out using LS-DYNA. Protection rings with the same mass and different groove depths are designed to study the influence of the groove depth. Simulation results including kinetic energy and impact force variation of single frag- ment are presented. It shows that the groove depth infects both the axial containment ability of the protection ring and the transfer process of energy. The depth of groove ought to be controlled to an appropriate value to meet both the requirement of axial containment and higher safety factor. Ver- ification test on high-speed spin tester has been conducted and shows that protection ring with appropriate U structure can resist the impact of the disk burst fragments. The ring is inflated from a circular to an oval-triangle shape. The corresponding simulation shows good agreement with the test.

涡轮发动机中篦齿-蜂窝封严结构的高速碰磨行为研究（英文）

目的：航空涡轮发动机中篦齿-蜂窝封严结构能有效降低转动部件之间的气路间隙,提高发动机效率。在高温高速可磨耗试验机上进行模拟试验,研究篦齿叶尖与金属蜂窝之间的高速碰磨行为,分析篦齿叶片和金属蜂窝的磨耗机理,验证金属蜂窝的可磨耗性能,为蜂窝封严在航空发动机中的应用提供参考。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5～1000μm/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。