GE公司成功试验世界下一代战斗发动机的首个陶瓷基复合材料（CMC）旋转件,由于CMC制成的旋转涡轮叶片仅为高压涡轮叶片上使用的传统镍基合金重量的1/3

GE公司成功试验世界下一代战斗发动机的首个陶瓷基复合材料旋转件
2015-02-12

    [据美国通用电气公司网站2015年2月10日报道]GE航空公司通过F414涡扇发动机验证机的旋转低压涡轮叶片成功试验了世界上首个非静子组件的轻质陶瓷基复合材料（CMC）部件。该验证机设计用于进一步验证GE公司当前与美国空军研究实验室（AFRL）合作开展的下一代自适应发动机技术验证机（AETD）项目在高应力工况下的耐高温材料。
    将旋转的CMC部件引入发动机工作温度最高、工况最恶劣的区域，代表了GE公司和喷气推进工业领域的重大技术突破。在F414 CMC验证机之前，CMC的成功应用仅限于静子件，如CFM公司研发用于空客A320neo、波音737MAX和中国商飞C919飞机的销量最好的LEAP发动机的高压涡轮罩环（shroud）。
    F414 CMC试验经历了500个严酷的循环，验证了轻质、耐高温CMC材料制造的涡轮叶片的极强的耐高温和耐久性能力，能够将该先进材料广泛用于GE公司自适应循环战斗发动机和下一代商用发动机。
    由于CMC制成的旋转涡轮叶片仅为高压涡轮叶片上使用的传统镍基合金重量的1/3，因此，GE公司可以减小连接到CMC系统的金属盘的尺寸和重量。GE航空负责CMC和先进聚合物基复合材料研究的总经理Jonathan Blank表示，发动机中从镍基合金到旋转CMC是一个真正的巨大飞跃，但这是纯机理。更轻的叶片导致更小的离心载荷，意味着轮盘、轴承和其他部件能够更薄。CMC带来了喷气发动机设计的革命性的变革。
    GE公司的自适应循环结构是独立地变革，将首次同时在静子和转子上采用CMC。2014年，GE公司完成了世界上仅有的自适应、三涵道技术验证机——自适应多用途发动机技术（ADVENT）发动机的试验。ADVENT发动机是世界航空史上首次同时采用CMC材料技术和从动力强劲的高压、小涵道比战斗机喷气发动机向燃油高效的低压、高涵道比商用发动机过渡的结构技术。
    ADVENT结合变革性结构和材料的创新带来了创纪录的温度和燃油效率。GE公司的AETD项目将建立在这些史无前例的推进能力上，实现相比当前最先进的第五代飞机燃油消耗量降低25%，航程增加30%，最大推力提高10%。
    GE航空先进作战发动机项目总经理Dan McCormick认为，将CMC从静子件向转子件过渡的一个关键挑战是必须适应相应的应力场。F414 CMC试验的进步提供了自适应循环发动机实现这一过渡的关键知识。CMC低压涡轮叶片的重量将仅为其替换的金属叶片重量的1/3，而且第二级CMC叶片不必空气冷却。由于当前并不是所有的叶片均需要压气机级中抽取的冷却空气，因此，当前叶片的气动效率能够更高。
    Blank说：“更高温意味着更多的冷却空气，这降低了发动机的总体性能和效率。通过降低部件的冷却需求，发动机能够气动更高效，而且燃油也更高效。由于CMC材料的温度能力比当前服役的军民用发动机的传统镍基合金要高几百摄氏度，因此，GE公司的自适应循环发动机将比传统发动机更具耐久性。”
    自上世纪90年代早期开始研发以来，GE公司已经投入了超过10亿美元开展由碳化硅陶瓷纤维和陶瓷树脂制成的CMC材料，由GE公司位于特拉华州和北卡罗来纳州的工厂通过高度复杂的工艺制造，并进一步通过独有的涂层来进一步增强性能。GE公司位于特拉华州纽瓦克的小型CMC生产工厂制造了用于F414试验的涡轮部件。GE公司位于北卡罗来纳州阿什维尔的大型生产工厂将生产LEAP发动机的静子部件。（中国航空工业发展研究中心 张小伟）

悍然不信，断裂韧性有问题。应该是下一代发动机经费需求的发展方向。

通用电气开发新型激光打孔工艺用于航空涡轮发动机叶片制造
2015-02-12
国外国防科技文献资料快报[据本站综合报道]航空涡轮发动机工作温度很高，甚至超过1370℃，已经接近所采用的钢材料的熔点。因此，发动机叶片需要采取非常复杂的方法进行冷却。工程师在叶片上加工出微细的小孔和通道保证冷空气的流通，以此对叶片进行保护。但叶片要以每分钟上千转的高速旋转且承受很大的压力，要在其正确的位置上打孔且不削弱叶片性能是非常复杂和困难的。生产企业通常都是采用激光束进行微小孔的加工，即用激光束加热叶片表面直到钢发生汽化，这一过程对精度要求很高，融化的金属材料会发生溅射或形成随空气传播的微观熔融团块，并粘附到叶片表面。

GE的制造工程师正在研发一种新的加工方式，利用瑞士喜诺发（Synova）公司开发的名为微水刀激光（Laser MicroJet）技术，采用冷加工的方式进行制孔加工。
微水刀激光是将一束激光射入如头发丝粗细的水柱中，水柱可以起到类似光纤的作用，将激光引导到叶片表面，还可以帮助降低材料周围的温度并清除加工产生的碎片。这一技术可以使工程师设计性能更好的涡轮发动机，并以更快的速度制造更耐用的零部件。
GE的工程师花费三年时间调整该方法使之适用于发动机制造，并逐步实现工程化应用。GE工程部主管James Cuny表示：“我们针对所需加工的几何形状重新设计了激光射流，在此之前，用于加工其他部件的激光射流设备所射出的激光像从大桶中流出来一样，根本无法满足我们的要求。”

GE已将该技术用于制造燃气涡轮叶片，目前正在考虑扩展到航空发动机等相关领域。
（北方科技信息研究所  商飞 胡晓睿）


http://www.gereports.com/post/11 ... e-a-water-jet-gives
Shooting Laser Beams Inside a Water Jet Gives Machining a New Cutting Edge
Leonardo da Vinci always seemed to be hungry for new ideas, but sometimes he may have been just hungry. Some 500 years ago, he designed a roasting jack that powered an automatic rotisserie. It used hot air rising from a fireplace to spin a horizontal vane placed in the chimney above it. The vane was attached to a vertical rod that turned the spit, and, presumably, his dinner.
The jack was one of the world’s first turbines and engineers have been using the same principle inside jet engines and power plants ever since. Since high heat can make turbines more efficient, the hot sections of modern turbines operate at temperatures above 2,500 degrees Fahrenheit, much higher than Leonardo’s design and near the melting point of steel.
For that reason, their blades, which are shaped like aircraft wings and machined to extreme accuracy, require very sophisticated ways of cooling. Engineers riddle the blades with a maze tiny channels and holes that bleed in enough cooling air to protect them. But making the holes in the right places without weakening the blades, which spin thousand of times per minute and must handle titanic pressures, is akin to magic.
Traditionally, companies have used lasers to make the tiny holes, heating the surface with the beam until the steel vaporizes. But that’s a delicate business. The metal can sputter and form molten microscopic gobbets that can spread through the air and stick to the finely machines metal surface.
Charlie Hu, an industrial manufacturing engineer at GE Power & Water, is exploring a different way. He is drilling cooling holes with a technology called Laser MicroJet developed by the Swiss company Synova.
The Laser MicroJet fires a laser beam inside a hair-thin jet of water, which acts like an optical fiber and guides the laser to the blade surface. The jet also helps cool down the surrounding material and flushes out machining debris. The technology could allow engineers to make more durable parts faster and design turbines that perform better.
Starting in 2011, it took Dr. Hu three years to adapt the method to turbines and take it out of the lab at GE Power & Water in Greenville, S.C. “We had to redesign the laser jet to the geometries we required,” says James Cuny, engineering executive at GE Power & Water. “Before this, the machine used for other applications was like a big barrel with a laser coming out of it. It was not very conducive to what we required.”
GE has already used the technology to make gas turbine blades. The company is now looking at applying it to other related businesses, such as aviation. “There is a lot of great development so far on this,” Cuny says.“Our engineers are excited about pushing the limits of the technology and bringing it to the market in the very near future.”
Dr. Hu’s mind is already on the next idea. Since the water jet can be also used to slice materials, GE and Synova are investing in a new technology that combines the advantages of both water and laser cutting in a single operation.
Leonardo invented his turbine while thinking about grilling. Hu’s ideas give GE a new cutting edge.
Engineers at GE Global Research are developing an ultra-efficient water-jet cutter that can blast through slabs of metal with ease. Here, the water jet is being tested to cut wind turbine parts from a solid aluminum ingot. It fires an abrasive mixture of garnet dust and plain water at a pressure of 60,000 pounds per square inch. The water-jet cutter could dramatically reduce manufacturing time at GE plants. Image credit: GE Global Research