曝光臺 注意防騙 網(wǎng)曝天貓店富美金盛家居專營店坑蒙拐騙欺詐消費(fèi)者

Early entry of the 9H is part of the H System. development strategy
to reduce risk. The 9H incorporates critical ATS design features and pro-vided early design verification. Also, because ATS goals required ad-vancements in virtually all components of the gas turbine,
GEPS incorporated its new systems approach for the
H System.—the “design for six sigma” (DFSS)
design process. DFSS accelerated development
by improving up-front definition of perfor-mance requirements and specifications
for subsystems and components, and by
focusing the research and development
activities. Downstream, the benefits
will be improved reliability, avail-ability, and maintainability due to
integration of manufacturing and
operational considerations into the
DFSS specifications.

GEPS’ 400-ton MS7001H in transit to full-speed, no-load testing

Meeting the Technical Challenges Turbine
The need to address the conflict-ing goals of higher efficiency and lower NOx emissions required sys-temic changes. The major driver was to increase the firing temperature (temperature into the first rotating turbine stage) without exceeding the NO formation combustion tem-
x

perature of 2,800 oF. To do so, GEPS introduced closed-loop steam cool-ing at the first and second stage nozzles and turbine blades (buckets) to reduce the differential between combustion and firing temperatures. The closed-loop steam cooling re-placed open-loop air cooling that depends upon film cooling of the airfoils.
In open-loop air cooling, a sig-nificant amount of air is diverted from the compressor and is intro-duced into the working fluid. This approach results in approximately a 280 oF temperature drop between the combustor and the turbine rotor inlet, and loss of compressed air en-ergy into the hot gas path.  Alterna-tively, closed-loop steam improves cooling and efficiency because of the superior heat transfer character-istics of steam relative to air, and the retention and use of heat in the closed-loop. The gas turbine serves as a parallel reheat steam generator for the steam turbine in its intended combined-cycle application.
The GEPS ATS uses a firing temperature class of 2,600 oF, ap-proximately 200 oF above the most efficient predecessor combined-cycle system with no increase in combustion temperature. To allow these temperatures, the ATS incor-porates several design features from aircraft engines.
Single crystal (nickel superal-loy) turbine bucket fabrication is used in the first two stages. This technique eliminates grain bound-aries in the alloy, and offers supe-rior thermal fatigue and creep characteristics. However, single crystal material characteristics con-tribute to the difficulty in airfoil manufacture, with historic applica-tion limited to relatively small hot section parts. The transition from manufacturing 10-inch, two-pound aircraft blades to fabricating blades 2–3 times longer and 10 times heavier represents a significant challenge. Adding to the challenge is the need to maintain very tight airfoil wall thickness tolerances for cooling, and airfoil contours for aerodynamics.
　
中國航空網(wǎng) www.k6050.com
航空翻譯 www.aviation.cn
本文鏈接地址：Advanced Turbine Systems 先進(jìn)的渦輪系統(tǒng)(4)