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[分享] 普及下知识: 涡扇与涡喷发动机

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发表于 2008-8-11 20:21:01 | 显示全部楼层 |阅读模式
让我们先看一下航空喷气式发动机的主要内部结构巴,首先不包括进气道,因进气道属机体结构,但必须与发动机一体化考虑否则发动机在一些条件下会产生如喘振等重大问题。喷气式发动机(涡扇)从前至后主要结构部件有,低压风扇,高压风扇,高压压气机,低压压气机,燃烧室,高压涡轮,低压涡轮,加力燃烧室,尾喷口。涡轮产生的动力通过传动轴带动压气机和风扇由於压气机和风扇转速不同要有减速部件因此大多现代喷气式发动机都是双轴的,三轴更好但增加结构复杂性重量大,仅英国的R&R既所谓的劳死累死公司的产品是三轴的,许多岛内的外行的军事专家及那姘可夫什么的称之为双路,实际上不懂装懂所讲出的外行话,根本不知道是什么.

如果去掉风扇(当然没那么简单)则变成了涡喷。涡喷的动力是由尾喷口排出的高速燃气产生,而涡扇一部分动力是由风扇通过外涵道排气产生,压气机至尾喷口称为内涵道,外涵道与内涵道气流量的比值称为流量比。

涡扇工作效率比较高油耗低,现代大多数喷气飞机都采用涡扇。然而, 涡扇的优点是有条件的不是绝对的,在高空高速条件下,由於进气流的速度快动压高,直接进入涡喷的压气机会产生人们所说的冲压效应,此时压气机工作效率迅速提高,涡喷全机的工作状态全面上升,涡喷与涡扇相比几乎所有的缺点此刻都不复存在,发动机推力急剧上升而油耗反而下降...,而涡扇由於风扇的影响此时外涵道反而成了累赘,为了即保证中低空性能又兼顾高空性能现代战斗机都采用小流量比的涡扇,以使高空高速性能接近与涡喷(仍然有差距)。

10年前为竞争YF22/23的F120发动机,GE公司投巨资开发变循环技术,既在中低空是台较高流量比的涡扇以提高效率,在高速尤其是超音速巡航时关闭外涵道使得F120成为一台涡喷,由於技术太复杂风险高加上矢量推力技术不成熟,终於败给了PW的小流量比F119,这是后话。

喷气发动机非常复杂涉及到气动结构传热等几乎所有的先进工业技术,仅美国的PW,GE,英国的RR,及俄国的一两家设计局有独立开放先进核心机技术,法国是二流水平,中国也只是刚刚入门。

有能力制造压气机叶片并不说明你会造发动机,日本引进F15 及F100 技术多年,风扇,压气机,加力燃烧室,尾喷口及传动附件都是三菱重工等生产,依然没有用,核心机技术依然掌握在美国手里,燃烧室涡轮才是关键。

你会制造所有的部件并不等於你知道原理,因为航空发动机实在是太复杂,体积小,重量轻,功率/推力非常大而工作环境恶劣。

小小的叶片每分钟转速高达几万转,加上气动力,涡轮叶片工作环境温度高达近2000摄氏度,再好的合金钢在此温度场下早化成液体,一般都是用超级镍基合金,叶片内部有冷却通路,在如此恶劣的工况下叶片的变形必须保持非常小否则气动会失效。此外叶片必须采用单晶铸造,此技术只有美英法俄及中国掌握。高温高速下的气动,燃烧传热过程,不经过几代人的努力及巨资投入想都别想,即使在美国这样技术先进成熟的国家开放新发动机也是动辄数亿美元甚至10亿美元以上。
发表于 2008-8-11 21:39:37 | 显示全部楼层
学习了... 顺便问下 目前有实战装备的涡喷么?
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 楼主| 发表于 2008-8-11 22:32:27 | 显示全部楼层
原帖由 狮心王理查 于 2008-8-11 21:39 发表
学习了... 顺便问下 目前有实战装备的涡喷么?

F-22,采用双模态发动机F119,以亚音速飞行时,发动机工作在涡扇模式,当飞机以1.58马赫巡航时,发动机转换为涡喷模式。
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发表于 2008-8-11 22:43:09 | 显示全部楼层
原帖由 HammerSun 于 2008-8-11 22:32 发表

F-22,采用双模态发动机F119,以亚音速飞行时,发动机工作在涡扇模式,当飞机以1.58马赫巡航时,发动机转换为涡喷模式。

哦 学习了 谢谢了~
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 楼主| 发表于 2008-8-11 22:46:59 | 显示全部楼层
涡扇引擎的涵道比(Bypass ratio)是不经过燃烧室的空气质量,与通过燃烧室的空气质量的比例。
旁通比为零的涡扇引擎即是涡轮喷射引擎。
至于F119发动如何双模,等高人来解答吧,偶也不知道了。
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发表于 2008-8-11 22:52:08 | 显示全部楼层
原帖由 HammerSun 于 2008-8-11 22:46 发表
涡扇引擎的涵道比(Bypass ratio)是不经过燃烧室的空气质量,与通过燃烧室的空气质量的比例。
旁通比为零的涡扇引擎即是涡轮喷射引擎。
至于F119发动如何双模,等高人来解答吧,偶也不知道了。 ...

呵呵 那个知道的人应该不多了吧
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 楼主| 发表于 2008-8-11 23:00:21 | 显示全部楼层
原帖由 狮心王理查 于 2008-8-11 22:52 发表

呵呵 那个知道的人应该不多了吧

坛子里高手很多的。
我只能找到这么些关于F119的资料:

F119发动机
全称F119-PW-100,是为F-22A研制的双转子小涵道比加力涡扇发动机,采用可上下偏转的二维矢量喷管,上下偏转角度为20度,推力和矢量由数字电子系统控制。
长4.826米,最大直径1.13米,重1360千克,最大推力156千牛,推重比11.7。


F119-PW-100
The F119-PW-100 is an afterburning turbofan engine developed for the Lockheed Martin F-22 Raptor advanced tactical fighter by Pratt & Whitney.

The engine delivers thrust in the 35,000 lbf (160 kN) thrust class (156 kN) and is designed for supersonic flight without the use of afterburner (supercruise). Delivering almost 22% more thrust with 40% fewer parts than conventional, fourth-generation military aircraft engine models, the F119 allows sustained supercruise speeds of up to Mach 1.72 The F-119's nozzles incorporate thrust vectoring technology. These nozzles direct the engine thrust ±20° in the pitch axis to give the F-22A enhanced maneuverability. The F-22's maximum speed could possibly be close to Mach 2.5 but this is unlikely because of its airframe materials.

The Pratt & Whitney F135, which powers the Lockheed Martin F-35, is a derivative engine of the F119. It has 40,000 lbf (180 kN) of thrust, the most ever in a fighter engine.

----------------------------------------------------------------------------------------------------------------------------
F-22 Raptor F119-PW-100 Engine
The F-22 incorporates a pair of new, higher thrust-to-weight engines, the Pratt & Whitney F119-PW-100, which is designed for efficient supersonic operation without afterburner (called supercruise), and with increased durability over current engines. Advanced technologies incorporated in the F119 include integrated flight-propulsion controls and two-dimensional, thrust-vectoring engine nozzles, which will give the F-22 unprecedented aircraft maneuverability. Development of the F119 was conducted at Pratt & Whitney's West Palm Beach, FL, facility, while production takes place at the company's factories in Middletown, CT. Pratt & Whitney built 27 flightworthy engines during EMD.

Designed for efficient supersonic operation without afterburner use and with increased durability over today's engines, the F119 is a very high thrust-to-weight ratio engine. Advanced technologies in the F119 include integrated flight-propulsion controls and two-dimensional, thrust-vectoring engine nozzles. The F119 incorporates technology advances developed and verified in joint U.S. Air Force/Pratt &Whitney research programs and for other advanced fighter engines. It was designed using the "integrated product development" approach to ensure a balance between performance, safety and reliability, maintainability and low life-cycle cost. In addition, it has significantly fewer and more durable components than previous fighter engines.

The F119-PW-100 is a revolutionary advance in fighter aircraft propulsion. The F119 engine develops more than twice the thrust of current engines under supersonic conditions, and more thrust without afterburner than conventional engines with afterburner.

Each F-22 will be powered by two of these 35,000-pound-thrust-class engines. By comparison, the engines powering the Air Force's current F-15 and F-16 fighters have thrust ratings ranging from 23,000 to 29,000 pounds.

Jet engines achieve additional thrust by directly injecting fuel at the engine exhaust. The process, called afterburner, gives the aircraft a rocket-like boost as the fuel ignites in the exhaust chamber. The tradeoff is higher fuel consumption, a greater amount of heat, and consequently, greater visibility to the enemy.

The F119 can push the F-22 to supersonic speeds above Mach 1.4 even without the use of afterburner, which gives the fighter a greater operating range and allows for stealthier flight operation. The product of more than 40 years' research into high-speed propulsion systems, the F119 is proof that high-technology doesn't have to be complicated.

Performance of the F119 engine has generally been excellent in testing. Full-scale airframe static testing and the first of three (originally four) planned fatigue lifetimes of testing have been completed and the second fatigue life testing is nearly complete. The program now plans to complete three fatigue lifetimes prior to the completion of the ongoing engineering and manufacturing development phase in November 2005. Expansion of flight test into the high-speed, high-G load regions of the performance envelope is ongoing.

Design

A balanced approach to the design process, using a team approach called Integrated Product Development (IPD), led to an engine as innovative in its reliability and support as in its performance. Assemblers and flight line mechanics participated in the F119's design from its inception. The result is that ease of assembly, maintenance and repair are designed into the engine.

The F119 has 40 percent fewer major parts than current fighter engines, and each part is more durable and does its job more efficiently. Computational fluid dynamics (CFD), the study of airflow using advanced computers, led to the design of engine turbomachinery of unprecedented efficiency, giving the F119 more thrust with fewer turbine stages.

The F119 cuts requirements for support equipment and labor by one-half, which also saves precious space in airlifters in combat zone deployments. The F119 will require 75 percent fewer shop visits for routine maintenance than its predecessors.

Features


Integrally bladed rotors: In most stages, disks and blades are made from a single piece of metal for better performance and less air leakage.
Long chord, shroudless fan blades: Wider, stronger fan blades eliminate the need for the shroud, a ring of metal around most jet engine fans. Both the wider blades and shroudless design contribute to engine efficiency.
Low-aspect, high-stage-load compressor blades: Once again, wider blades offer greater strength and efficiency.
Alloy C high-strength burn-resistant titanium compressor stators: Pratt & Whitney's innovative titanium alloy increases stator durability, allowing the engine to run hotter and faster for greater thrust and efficiency.
Alloy C in augmentor and nozzle: The same heat-resistant titanium alloy protects aft components, permitting greater thrust and durability.
Floatwall combustor: Thermally isolated panels of oxidation-resistant high cobalt material make the combustion chamber more durable, which helps reduce scheduled maintenance.
Fourth-generation full-authority digital electronic engine control (FADEC): Dual-redundant digital engine controls - two units per engine, two computers per unit - ensure unmatched reliability in engine control systems. The same experience that introduced full-authority digital control to fighter engines works with the aircraft system to make engine and aircraft function as a single flight unit.
No visible smoke: Reduces the possibility of an enemy visually detecting the F-22.
Improved Supportability: All components, harnesses, and plumbing are located on the bottom of the engine for easy access, all line replaceable units (LRUs) are located one deep (units are not located on top of one another), and each LRU can be removed with just one of the six standard tools required for engine maintenance.
F119/F-22 Engine Nozzle

The F119 engine nozzle for the F-22 is the world's first full production vectoring nozzle, fully integrated into the aircraft/engine combination as original equipment.

The two-dimensional nozzle vectors thrust 20 degrees up and down for improved aircraft agility. This vectoring increases the roll rate of the aircraft by 50 percent and has features that contribute to the aircraft stealth requirements.

Heat-resistant components give the nozzles the durability needed to vector thrust, even in afterburner conditions.

With precision digital controls, the nozzles work like another aircraft flight control surface. Thrust vectoring is an integrated part of the F-22's flight control system, which allows for seamless integration of all components working in response to pilot commands.

The nozzle is manufactured at Pratt & Whitney's West Palm Beach facility, home to the company's military engine design and prototype construction.

Engine Assembly and Test Facilities

Pratt & Whitney's West Palm Beach, Fla., facility is the focal point for its military engine development activities. But given the Integrated Product Development process, which gives manufacture, assembly, and maintenance personnel a larger role in engine design, F119 development activities have also incorporated its eventual producers at company facilities in Middletown, East Hartford, and New Haven, Conn.; North Berwick, Me.; and Columbus, Ga.

Sea-level testing was conducted at the West Palm Beach facility. Extensive altitude testing was done at the Air Force's Arnold Engineering Development Center, Arnold AFB, Tullahoma, Tenn.

Most F119 assembly work will be conducted in Middletown, Conn., where Pratt & Whitney employs 3,000 people in the manufacture of combustors, engine cases, and major rotating parts. Middletown is a two-million square foot facility on 1,100 acres.

Components for the 26 F119 engines to be built during the current Engineering and

Manufacturing Development (EMD) phase are being produced in Middletown. At the conclusion of the proof-of-concept program, the facility and its people will have gained engine production experience and will be ready to gear up for full F119 production in support of the F-22 and Joint Strike Fighter (JSF) programs.

Components will be made by suppliers in states across the nation and at these Pratt & Whitney facilities: East Hartford, Conn.: Pratt & Whitney employs 7,800 employees in this 5.2-million square foot facility, which houses Large Commercial Engines headquarters, commercial engineering, marketing, and product support, overhaul and repair operations and manufacturing facilities. The facility specializes in single-crystal turbine blades, fans, and compressor blades, as well as commercial engine production.

North Haven, Conn.: The 1,600 employees in this 800,000-square-foot facility make turbine and compressor blades and vanes.
North Berwick, Me.: Here, 1,500 employees in an 880,000 square-foot facility manufacture blades, vanes, bearing compartments, and stators.
Columbus, Ga.: The 250 employees at Pratt & Whitney's newest manufacturing plant forge disks and other engine components.
Schedule

In the Engineering and Manufacturing Development (EMD) phase of the program, Pratt & Whitney designed, developed, and qualified three products: 26 flight test engines, the F119 support system, and the F119 training system.

Plans call for the production of 1,000 F119 engines. This number will provide engines for the 438 planned aircraft (two per aircraft) plus sufficient spares.

F-22 Airframe Mounted Accessory Drive (AMAD)

Built by Boeing, the F-22 Airframe-Mounted Accessory Drive (AMAD) transfers shaft power from the Air Turbine Starter System (ATSS) to the F119 engines for engine starts, and from the engines to a generator and hydraulic pumps for the electrical and hydraulic systems.

The AMAD transmits power required by the high-performance F-22 throughout the flight envelope and incorporates a high-reliability lubrication system that services the AMAD-mounted generator and ATSS as well as gearbox components.

Engine Trailer

The Boeing-developed F-22 engine trailer (designated A/M32M-34) is a piece of ground support equipment that is required for installation and removal of the Pratt & Whitney F119 engines. The trailer also supports the engine for on-base towing, air, and truck shipment. For air and truck shipment a shipping adapter (a support frame that fits over the top of the engine and attaches to the trailer to secure the engine) is also required.

During engine installation, the trailer provides a six-axis (vertical, lateral, pitch, roll, and yaw) adjustment capability to precisely align the engine to the aircraft. Fine adjustments in the vertical and lateral directions are also provided for load transfer of the engine to/from the aircraft.

Once aligned, the engine slides from the trailer's rails directly to a similar set of extension rails placed in the aircraft's engine bay. From there, the engine is pushed on to the engine mounts The lower segments of two of the aircraft's engine bay frames (numbers 5 and 6) drop down to allow for engine fitting.

There are only eight connections that have to be made between the engine and the aircraft, and with the drop out links, maintainers will be able to remove and replace an engine in approximately 75 minutes.

The engine trailer is approximately 14 feet in length and 6 feet wide. When fully lowered by means of its mechanically actuated scissors lift assembly, the trailer's height is only 38 inches. Maximum height is 5 feet. The empty weight of the trailer is 3,400 pounds. The trailer's maximum payload capacity is 7,500 pounds.

[ 本帖最后由 HammerSun 于 2008-8-11 23:01 编辑 ]
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 楼主| 发表于 2008-8-11 23:05:49 | 显示全部楼层
上个F119的大图3张:




[ 本帖最后由 HammerSun 于 2008-8-11 23:07 编辑 ]
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发表于 2008-8-11 23:09:43 | 显示全部楼层
谢谢 锤大... 不过又要考验我可怜的英语了... 先收下 慢慢研究... 都快一年没看航空方面的东西了... 一直在看海军...
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发表于 2008-8-11 23:30:37 | 显示全部楼层
以下是yahoo在线翻译 机翻的 不过勉强将就能看个大概吧...
第一段
F119-PW-100是为洛克希德马丁公司F-22猛禽先进的作战战斗机发展的复燃涡轮风扇引擎由普拉特&惠特尼。

The引擎提供在35,000 lbf (160 kN)被推的类(156的推力kN)和为超声速飞行设计,不用使用加力燃烧室(supercruise)。 交付差不多22%更推与40%少量部分比常规,第四代军用飞机引擎模型, F119提供由马赫1.72决定的被承受的supercruise速度导航技术的F-119喷管合并推力。 这些喷管在俯仰轴指挥引擎推力±20°给F-22A改进的操纵性。 F-22最大速度可能可能是接近马赫2.5,但是这是不太可能的由于它的飞机机架材料。

The普拉特&惠特尼F135,供给洛克希德马丁公司F-35动力,是F119的一个衍生物引擎。 它有40,000 lbf (180 kN)推力,在战斗机引擎。
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