Editing Gas turbine (section)

==Advances in technology==
Gas turbine technology has steadily advanced since its inception and continues to evolve. Development is actively producing both smaller gas turbines and more powerful and efficient engines. Aiding in these advances are computer-based design (specifically [[computational fluid dynamics]] and [[finite element analysis]]) and the development of advanced materials: Base materials with superior high-temperature strength (e.g., [[single-crystal]] [[superalloy]]s that exhibit [[yield strength anomaly]]) or [[thermal barrier coatings]] that protect the structural material from ever-higher temperatures. These advances allow higher [[compression ratio]]s and turbine inlet temperatures, more efficient combustion and better cooling of engine parts.

[[Computational fluid dynamics]] (CFD) has contributed to substantial improvements in the performance and efficiency of gas turbine engine components through enhanced understanding of the complex viscous flow and heat transfer phenomena involved. For this reason, CFD is one of the key computational tools used in design and development of gas<ref>{{cite web |url=http://www.hcltech.com/sites/default/files/CFD_for_Aero_Engines.pdf |title=CFD for Aero Engines |publisher=HCL Technologies |date=April 2011 |access-date=13 March 2016 |archive-date=9 July 2017 |archive-url=https://web.archive.org/web/20170709034400/https://www.hcltech.com/sites/default/files/CFD_for_Aero_Engines.pdf |url-status=dead }}</ref><ref>{{Cite journal|last1=Chrystie|first1=R|last2=Burns|first2=I|last3=Kaminski|first3=C|date=2013|title=Temperature Response of an Acoustically Forced Turbulent Lean Premixed Flame: A Quantitative Experimental Determination|journal=Combustion Science and Technology|volume=185|pages=180–199|doi=10.1080/00102202.2012.714020|s2cid=46039754}}</ref> turbine engines.

The simple-cycle efficiencies of early gas turbines were practically doubled by incorporating inter-cooling, regeneration (or recuperation), and reheating. These improvements, of course, come at the expense of increased initial and operation costs, and they cannot be justified unless the decrease in fuel costs offsets the increase in other costs. The relatively low fuel prices, the general desire in the industry to minimize installation costs, and the tremendous increase in the simple-cycle efficiency to about 40 percent left little desire for opting for these modifications.<ref>{{cite book |last1=Çengel |first1=Yunus A. |first2=Michael A. |last2=Boles. |title=9-8. Thermodynamics: An Engineering Approach |edition= 7th |location=New York |publisher=McGraw-Hill |year=2011 |page=510}}</ref>

On the emissions side, the challenge is to increase turbine inlet temperatures while at the same time reducing peak flame temperature in order to achieve lower NOx emissions and meet the latest emission regulations. In May 2011, [[Mitsubishi Heavy Industries]] achieved a turbine inlet temperature of {{cvt|1600|C|F|round=50}} on a 320 megawatt gas turbine, and 460 MW in gas turbine [[combined-cycle]] power generation applications in which gross [[thermal efficiency]] exceeds 60%.<ref>{{cite web |title=MHI Achieves 1,600&nbsp;°C Turbine Inlet Temperature in Test Operation of World's Highest Thermal Efficiency "J-Series" Gas Turbine |publisher=Mitsubishi Heavy Industries |date=26 May 2011 |url= http://www.mhi.co.jp/en/news/story/1105261435.html |archive-url= https://web.archive.org/web/20131113162749/http://www.mhi.co.jp/en/news/story/1105261435.html |archive-date=2013-11-13}}</ref><ref>{{cite tech report |url=https://asmedigitalcollection.asme.org/GT/proceedings-abstract/GT2012/44694/599/289409?redirectedFrom=PDF |title=Evolution and Future Trend of Large Frame Gas Turbines: A New 1600 Degree C, J Class Gas Turbine |first1=Satoshi |last1=Hada |first2=Masanori |last2=Yuri |first3=Junichiro |last3=Masada |first4=Eisaku |last4=Ito |first5=Keizo |last5=Tsukagoshi |publisher=The American Society of Mechanical Engineers |doi=10.1115/GT2012-68574 |date=2013-07-09 |access-date=2023-12-23 |url-access=subscription}}</ref>

Compliant [[foil bearing]]s were commercially introduced to gas turbines in the 1990s. These can withstand over a hundred thousand start/stop cycles and have eliminated the need for an oil system. The application of microelectronics and [[power switching]] technology have enabled the development of commercially viable electricity generation by microturbines for distribution and vehicle propulsion.

In 2013, General Electric started the development of the [[GE9X]] with a compression ratio of 61:1.<ref>{{cite web|url=https://www.flightglobal.com/analysis-ge-opens-five-year-development-effort-for-777x-engine/109167.article|title=ANALYSIS: GE opens five-year development effort for 777X engine|first=Stephen|last=Trimble|date=2013-03-22|website=Flight Global}}</ref>