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Journal articles on the topic "A-22 (Jet fighter plane)"
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Wang, Zheng, and Kevin Avruch. "Culture, Apology, and International Negotiation: The Case of the Sino-U.S. "Spy Plane" Crisis." International Negotiation 10, no. 2 (2005): 337–54. http://dx.doi.org/10.1163/1571806054740958.
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AbstractThis article traces the course of the Sino-U.S. negotiation in April 2001, to resolve the crisis following the collision of a U.S. surveillance aircraft with a Chinese fighter jet off of China's coast and the subsequent unauthorized emergency landing of the U.S. plane at a Chinese airfield on Hainan Island. The negotiation focused on the Chinese demand for a full apology from the United States and the U.S. resistance to this demand. The article examines the role that culture, particularly linguistic differences, played in the course of the negotiation and its eventual resolution.
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KARACOR, ADIL GURSEL, ERDAL TORUN, and RASIT ABAY. "AIRCRAFT CLASSIFICATION USING IMAGE PROCESSING TECHNIQUES AND ARTIFICIAL NEURAL NETWORKS." International Journal of Pattern Recognition and Artificial Intelligence 25, no. 08 (December 2011): 1321–35. http://dx.doi.org/10.1142/s0218001411009044.
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Identifying the type of an approaching aircraft, should it be a helicopter, a fighter jet or a passenger plane, is an important task in both military and civilian practices. The task in question is normally done by using radar or RF signals. In this study, we suggest an alternative method that introduces the use of a still image instead of RF or radar data. The image was transformed to a binary black and white image, using a Matlab script which utilizes Image Processing Toolbox commands of Matlab, in order to extract the necessary features. The extracted image data of four different types of aircraft was fed into a three-layered feed forward artificial neural network for classification. Satisfactory results were achieved as the rate of successful classification turned out to be 97% on average.
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Shao, Yang, Zhen Peng, Kheng Hwee Lim, and Jin-Fa Lee. "Non-conformal domain decomposition methods for time-harmonic Maxwell equations." Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 468, no. 2145 (April 4, 2012): 2433–60. http://dx.doi.org/10.1098/rspa.2012.0028.
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We review non-conformal domain decomposition methods (DDMs) and their applications in solving electrically large and multi-scale electromagnetic (EM) radiation and scattering problems. In particular, a finite-element DDM, together with a finite-element tearing and interconnecting (FETI)-like algorithm, incorporating Robin transmission conditions and an edge corner penalty term , are discussed in detail. We address in full the formulations, and subsequently, their applications to problems with significant amounts of repetitions. The non-conformal DDM approach has also been extended into surface integral equation methods. We elucidate a non-conformal integral equation domain decomposition method and a generalized combined field integral equation method for modelling EM wave scattering from non-penetrable and penetrable targets, respectively. Moreover, a plane wave scattering from a composite mockup fighter jet has been simulated using the newly developed multi-solver domain decomposition method.
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Lams, Lutgard. "Linguistic tools of empowerment and alienation in the Chinese official press." Pragmatics. Quarterly Publication of the International Pragmatics Association (IPrA) 20, no. 3 (September 1, 2010): 315–42. http://dx.doi.org/10.1075/prag.20.3.02lam.
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Attempts at reinvigorating mythical sensations of shared values and cultural identities happen particularly at times of dislocatory events in a community’s history, when ‘the national Self’ is perceived to be threatened by external forces. Such a critical moment for China was the collision between a US surveillance plane and a Chinese F-8 jet fighter on April 1, 2001, and the ensuing diplomatic standoff between the US and China. As the Chinese authorities and the state media viewed this incident in a series of ambiguous incidents involving the US, it was concluded that the collision had been the inevitable outcome of US hegemonism intended to provoke China. It is this concurrence of events, triggering feelings of disempowerment of the Self that causes recurrent flurries of heated anti-Other rhetoric. Boundaries of exclusion/inclusion along cultural, historical and political lines set up the Other as the negative mirror of the Self, which as a consequence is positively reasserted. Informed by insights from Language Pragmatics and Critical Discourse Analysis, this paper sets out to examine linguistic tools of alienation and empowerment in the Chinese official press narratives about the collision, comprising the Chinese-language Renmin Ribao, its English equivalent The People’s Daily and the English-language China Daily. It aims to trace processes of meaning generation, in particular discursive practices of an ideological nature, such as antagonistic portrayals of in- and outgroups, hegemonic exercise of power, as well as naturalized conceptualizations of contingent processes, structures and relations.
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SMITH, NICK. "BEATRICE SHILLING: BATTLE OF BRITAIN INNOVATOR." Engineer 301, no. 7924 (February 2021): 48–49. http://dx.doi.org/10.12968/s0013-7758(22)90438-6.
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Alves, Pedro, Miguel Silvestre, and Pedro Gamboa. "Aircraft Propellers—Is There a Future?" Energies 13, no. 16 (August 11, 2020): 4157. http://dx.doi.org/10.3390/en13164157.
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The race for speed ruled the early Jet Age on aviation. Aircraft manufacturers chased faster and faster planes in a fight for pride and capability. In the early 1970s, dreams were that the future would be supersonic, but fuel economy and unacceptable noise levels made that era never happen. After the 1973 oil crisis, the paradigm changed. The average cruise speed on newly developed aircraft started to decrease in exchange for improvements in many other performance parameters. At the same pace, the airliner’s power-plants are evolving to look more like a ducted turboprop, and less like a pure jet engine as the pursuit for the higher bypass ratios continues. However, since the birth of jet aircraft, the propeller-driven plane has lost its dominant place, associated with the idea that going back to propeller-driven airplanes, and what it represents in terms of modernity and security, has started a propeller avoidance phenomenon with travelers and thus with airlines. Today, even with the modest research effort since the 1980s, advanced propellers are getting efficiencies closer to jet-powered engines at their contemporary typical cruise speeds. This paper gives a brief overview of the performance trends in aviation since the last century. Comparison examples between aircraft designed on different paradigms are presented. The use of propellers as a reborn propulsive device is discussed.
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Haber, Ralph Norman. "Why Low-Flying Fighter Planes Crash: Perceptual and Attentional Factors in Collisions with the Ground." Human Factors: The Journal of the Human Factors and Ergonomics Society 29, no. 5 (October 1987): 519–32. http://dx.doi.org/10.1177/001872088702900502.
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A detailed analysis of a recent jet fighter mishap is made in terms of perceptual and attentional factors that may have contributed to or caused the mishap. The crash occurred in clear air while the fighter was maneuvering over rugged terrain of irregular and unpredictable features. There were no mechanical failures and no evidence of pilot error. The analysis concentrates on the effects of the underinformativeness of the terrain; the difficulties of perceiving distance, ground clearance, and position under these conditions; the consequences of the high gravitational forces generated by the jet just prior to impact; and the competition for the pilot's visual attention. The effects of the combinations of these various factors are then considered. Finally, specific suggestions are made for improvements in training for low-altitude flight.
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James, Michael M., Kent L. Gee, Alan T. Wall, J. Micah Downing, Kevin A. Bradley, and Sally Anne McInerny. "Aircraft jet source noise measurements of a Lockheed Martin F‐22 fighter jet using a prototype near‐field acoustical holography measurement system." Journal of the Acoustical Society of America 127, no. 3 (March 2010): 1878. http://dx.doi.org/10.1121/1.3384569.
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Gal-Or, Benjamin. "Expanded R&D by Jet-engine-steering Revolution." International Journal of Turbo & Jet-Engines 34, no. 4 (October 26, 2017): 305–11. http://dx.doi.org/10.1515/tjj-2017-5001.
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Abstract Since 1987 [1, 2, 3, 4, 5] the global jet engine community is facing the historical fact that jet engine steering is gradually replacing canards and the common, often dangerous and obsolete, aerodynamic-only flight control – a fact that (i) has already affected the defense-industrial complex in the US, Russia, China, Japan, S-Korea and India, (ii) has integrated the traditional jet-engine components R&D with advanced aero-electro-physics, stealth technology, thrust vectoring aerodynamics and material science. Moreover, this military revolution is historically due to expand into the civil transport jets domain, [6, 7, 8, 9]. The historical aim of the JES-Revolution remains the same: Replace the common, stall-spin sensitive canards [6] and Aerodynamic-Only-Obsolete-Flight Control (“AOOF Control”). Invented about 100 years ago for propeller-driven air vehicles, it has already been partially replaced for failure to function in WVR-combat post-stall domain, and for the following reasons: In comparison with complete Tail-Less, Canard-Less, Stealth-JES (Figure 5 and References [1, 2, 3, 4, 5, 6]), the common AOOF Control increases drag, weight, fuel consumption, complexity, cost, and reduces flight safety, stealth, [Low Detectability] and provides zero post-stall, WVR air combat capability while its CANARDS KILL LD & REDUCE JES. Examples of stealth fighter aircraft that have already replaced canards and AOOF-Control where JES provides at least 64 to 0 KILL-RATIO advantage over AOOF-Controlled conventional fighter aircraft: The U.S. JES F-22 and, apparently, the Russian JES-Su-T-50 & 35S, China 2016-J-31, Indian HAL AMCA & FGFA, Japanese JES IHHI ATD-X, S-Korean JES KF-X. Cf. X-44 in Figure 5. Consequently, the jet engine is no longer defined as providing only brute force forward. Instead, it successfully competes with and wins over the wrong, dominating AOOF-Control, at least as a backup flight control whose sole factual domain is currently a well-established, primary flight controller RE any post-stall, super-agility, [2, 3, 4, 5, 6, 7, 8, 9].
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Reis, Rachelle Simões, José F. C. Henriques, Guilherme Janson, Karina Maria Salvatore Freitas, and Wilana Moura. "Dental, skeletal and soft tissue effects of the Distal Jet appliance: A prospective clinical study." Dental Press Journal of Orthodontics 24, no. 6 (December 2019): 56–64. http://dx.doi.org/10.1590/2177-6709.24.6.056-064.oar.
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ABSTRACT Objective: This study evaluated the dental, skeletal and soft tissue effects in Class II malocclusion patients treated with Distal Jet appliance, compared to an untreated control group. Methods: 44 patients with Class II malocclusion were divided into two groups: Group 1 (experimental) - 22 patients, mean age of 12.7 years, treated with the Distal Jet appliance for a mean period of 1.2 years; Group 2 (control) - 22 untreated patients, mean age of 12.2 years, followed by a mean period of 1.2 years. Lateral cephalograms were obtained before treatment (T0) and at the end of the distalization (T1).Independent t test was used to identify intergroup differences. Results: When compared to control group, the Distal Jet produced a significant increase in mandibular plane angle (0.7 ± 2.0o). The maxillary second molars presented distal inclination (6.6 ± 3.8o), distalization (1.1 ± 1.1 mm) and extrusion (1.3 ± 2.1 mm). The maxillary first molars distalized by 1.2 ± 1.4 mm. The maxillary first premolars mesialized by 3.4 ± 1.1 mm. The maxillary incisors showed slight labial tipping of 4.3 ± 4.7o and were protruded by 2.4 ± 1.7 mm. There were no significant changes in the facial profile. The overjet increased 1.5 ± 1.1 mm and overbite had no significant changes. Conclusion: The Distal Jet appliance is effective to distalize the maxillary first molars, but promotes increase in mandibular plane angle, distal inclination, extrusion and distalization of maxillary second molars, mesialization of maxillary first premolars, proclination and protrusion of maxillary incisors, and increase in overjet, when compared to a control group.
Dissertations / Theses on the topic "A-22 (Jet fighter plane)"
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Beales, Brian O. "F-22 versus UCAV fixing today's deficiencies leaves questions about tomorrow's dominance." Thesis, Monterey, California : Naval Postgraduate School, 2009. http://edocs.nps.edu/npspubs/scholarly/theses/2009/Dec/09Dec%5FBeales.pdf.
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Thesis (M.A. in Security Studies (Homeland Security and Defense))--Naval Postgraduate School, December 2009.Thesis Advisor(s): Looney, Robert E. ; McNab, Robert M. "December 2009." Description based on title screen as viewed on January 27, 2010. Author(s) subject terms: F-22, MQ-1, MQ-9, UCAV, homeland defense, aircraft effectiveness, defense spending, manned flight, unmanned flight. Includes bibliographical references (p. 71-76). Also available in print.
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Simon, Yolande. "Prospects for the French fighter industry in a post-cold war environment is the future more than a mirage? /." Santa Monica, CA : RAND, 1993. http://www.rand.org/pubs/rgs%5Fdissertations/RGSD106/.
Full textBooks on the topic "A-22 (Jet fighter plane)"
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Lockheed Martin F/A-22 Raptor: Stealth fighter. [Hinckley, England]: Aerofax, 2005.
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Controlling costs in tactical aircraft programs: Hearing before the Subcommittee on National Security, Emerging Threats and International Relations of the Committee on Government Reform, House of Representatives, One Hundred Eighth Congress, first session, April 11, 2003. Washington, D.C: U.S. G.P.O., 2003.
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Kinzey, Bert. F-14 A & B Tomcat: Su-22 killer : in detail & scale. Blue Ridge Summit, PA: Aero, 1987.
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YF-22 and YF-23 advanced tactical fighters: Stealth, speed and agility for air superiority. Osceola, WI: Motorbooks International, 1991.
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Bolkcom, Christopher C. F-22 aircraft program. [Washington, D.C.]: Congressional Research Service, Library of Congress, 2000.
Find full textBook chapters on the topic "A-22 (Jet fighter plane)"
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Toal, Gerard. "Geopolitics Thick and Thin." In Near Abroad. Oxford University Press, 2017. http://dx.doi.org/10.1093/oso/9780190253301.003.0014.
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On November 24, 2015, a Turkish F-16 fighter jet shot down a Russian Sukhoi Su-24M aircraft on the Syria-Turkey border. For seventeen seconds the Russian aircraft crossed the southern tip of a salient of Turkish territory that Syria claimed rightfully belonged to it. Two Russians ejected from the plane over Syria. A local Turkmen militia, commanded by a Turkish citizen, fired at the aviators, killing one. A second Russian serviceman was killed during a rescue mission to save the surviving aviator. The incident, recorded on radar systems by many countries and partially captured on video camera, was the first time since the Korean War that a North Atlantic Treaty Organization (NATO) country’s fighter jet destroyed a Soviet/Russian Air Force aircraft. Fortunately the event did not escalate into a full-blown NATO Russia crisis, although with tensions high over the Ukraine crisis and two authoritarian leaders at loggerheads, it could well have done so. There were background accusations. Turkish president Erdoğan was aggrieved that Russia was bombing co-ethnic kin in its southern near abroad while aiding Kurdish separatists, while Russian president Putin saw Turkey as an accomplice of international terrorists. Entwined territorial and terrorist anxieties, as well as near abroad insecurities, preoccupied both men. Had Russia responded with force against Turkey, this could have triggered Article V of NATO’s Washington Treaty, and NATO members would have faced the prospect of war with Russia over a tiny piece of territory in the Middle East most knew nothing about. Relations between the NATO alliance and Russia are now at their lowest point since the collapse of the Soviet Union. Airspace violations, incidents at sea, military training exercises, and hybrid war hysteria have kept tensions high. After Crimea, NATO moved to strengthen its capacity to respond to perceived Russian encroachment on the Baltic countries. The Obama administration’s European Reassurance Initiative was launched in June 2014 with a $1 billion budget for training and temporary rotations. In a speech in Riga in September 2014, President Obama declared: “We’ll be here for Estonia.
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Chen, Beatrice. "“Resist the Earthquake and Rescue Ourselves”: The Reconstruction of Tangshan after the 1976 Earthquake." In The Resilient City. Oxford University Press, 2005. http://dx.doi.org/10.1093/oso/9780195175844.003.0017.
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At 8:02 a.m. on the morning of July 28, 1976, approximately five hours after an earthquake struck Tangshan in northeastern China, a MIG-8 fighter jet landed at the People’s Liberation Army base nine kilometers from the sprawling industrial city of Tangshan. Two army officers quickly ran toward the plane and an officer named Lee asked, “What is the flight’s mission?” The pilot replied, “We are looking for the epicenter of the earthquake.” Without checking the identity or credentials of the other passengers, Lee anxiously asked the pilot to fly over Tangshan and confirm his suspicion that the epicenter lay under the city. As Lee watched the plane fly toward Tangshan, he radioed the pilot, “Can you see Tangshan yet?” Through the speakers came the pilot’s shaky voice, “Yes, where it used to be!” When the earthquake shook Tangshan out of its slumber in the early hours of that summer morning, nobody imagined that it would turn the city into a vast ruin. Not a single structure in this city of thirtythree square kilometers escaped unharmed from this earthquake, which registered 7.8 on the Richter scale. Fully 78 percent of Tangshan’s industrial buildings and 97 percent of its residential buildings were leveled. The enormity of the physical destruction could only mean a comparable scale of human calamity. The official death toll stands at 240,000, but outside sources have posted much higher figures. Some current residents still believe that the death toll is at least twice that of the official tally. One third-generation Tangshan resident pointed out, “Not one single building escaped earthquake damage. How can the government officials say that only one quarter of the Tangshan population perished in this disaster?” To this day, the true death toll remains a haunting unknown. What is certain is that within three seconds on July 28, 1976, Tangshan was obliterated from the earth by a natural force roughly 400 times that of the atom bomb dropped on Hiroshima. It is conceivable that if the earthquake had not been detected by a number of seismological centers around the globe, the news of this great catastrophe would never have reached the outside world.
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Hiro, Dilip. "Multi-front Cold War between Riyadh and Tehran." In Cold War in the Islamic World, 275–312. Oxford University Press, 2019. http://dx.doi.org/10.1093/oso/9780190944650.003.0013.
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When rebel Houthis, followers of Zaidi Shia code, captured Sanaa in September 2014, and expelled Yemen’s Sunni President Abd Rabbu al Hadi, alarm bells rang in Riyadh. Deputy Crown Prince Muhammad bin Salman led a coalition of friendly states to intervene in the Yemeni civil war in March 2015. This ignited protest by the Shias in Saudi Arabia. Their indignation intensified when, ignoring international appeals for clemency, the Saudi government executed their revered Ayatollah Nimr al Nimr in January 2016. This led to the severance of diplomatic ties between Riyadh and Tehran. In Iraq, whereas Iran dispatched its trained Shia volunteers to fight Islamic Sate in Syria and Iraq (ISIS), Riyadh lent four jet fighters to the Pentagon in Washington’s anti-ISIS campaign. When Riyadh backed Syrian opposition with cash and weapons, Russian President Vladimir Putin sent air force units to Syria, and shored up Assad’s depleted arms arsenal. With Assad’s recapture of Eastern Aleppo, an opposition stronghold, in December 2016, Iran established superiority over Riyadh in Syria. In July 2015, Iran and six major world powers signed an accord on Tehran’s denuclearization program, titled Joint Comprehensive Plan of Action (JCPOA). It won universal approval except by Saudi Arabia and Israel.
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Rice, Mark. "The Junta and the Jipis, 1960–1975." In Making Machu Picchu, 98–128. University of North Carolina Press, 2018. http://dx.doi.org/10.5149/northcarolina/9781469643533.003.0005.
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Advances in jet travel ushered in Cusco’s first tourism boom in the 1960s and 1970s. However, a series of agrarian revolts and the collapse of Cusco’s traditional economic base threatened to unravel tourism. Increasingly, Cusco looked to the national state to use tourism as a source of economic development, especially after the 1968 military coup led by the left-leaning General Juan Velasco Alvarado. Working with transnational institutions like UNESCO and employing Machu Picchu as a populist symbol, the military sought to use cultural tourism with ongoing agrarian reform to remake Cusco’s regional society. Contrary to the military’s goals, these efforts ultimately failed. Plans to construct a modernist hotel at Machu Picchu provoked fights between development and preservation interests. In addition, the unexpected arrival of counter-cultural travellers shocked locals. Finally, the highly-technical strategies employed by the military and UNESCO only served to displace local control over tourism in favor of bureaucratic interests in Lima.
Conference papers on the topic "A-22 (Jet fighter plane)"
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Hackel, Lloyd A., C. Brent Dane, Jon Rankin, Fritz Harris, Chanh Truong, and Serena Marley. "Fatigue and SCC Lifetime Enhancement of Steels by Means of Laser Peening." In ASME 2011 Pressure Vessels and Piping Conference. ASMEDC, 2011. http://dx.doi.org/10.1115/pvp2011-58037.
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Laser peening is a technology employed to induce deep levels of plasticity in materials resulting in compressive residual stress to depths of 5mm (0.2 inches) or deeper enabling increased fatigue strength and lifetimes and greatly enhanced resistance to stress corrosion cracking. An advanced in Nd:glass laser technology has enabled high rate, cost effective industrial deployment of the technology that is now being widely used in aerospace and electric power generation applications. Examples of deep levels of compressive stress and resulting improvements in fatigue life and resistance to stress corrosion cracking will be shown. An advanced beam delivery technology incorporating a robotic arm coupled with a video detection/beam alignment system is enabling rapid setup and application in field applications. The technology has been approved and deployed to prevent early fatigue cracking of key structural components on the F-22 fighter jet. It is also being applied to oil and natural gas applications and has the potential to serve a broad base of field applications including oil and gas lines, on-board ship SCC, nuclear power plant SCC, and fatigue and corrosion applications in upstream exploration and downstream oil refining.
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Max, Philipp, Marcel Stößel, Michael Krummenauer, and Reinhard Niehuis. "Effectiveness of Active Flow Control Techniques in an Advanced S-Shaped Engine Intake." In GPPS Xi'an21. GPPS, 2022. http://dx.doi.org/10.33737/gpps21-tc-102.
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The development of modern military aircraft has to meet considerable requirements in terms of reducing the system weight, installation space, as well as radar signature. For fighter aircraft, serpentine intakes are commonly used since they reduce the radar visibility of the engine, the system weight, and allow the optimal use of the installation space. However, these intake systems cause flow disturbances for the engine. To avoid penalties in engine performance, active flow control methods can be implemented for controlling the flow through the intake. The experiments undertaken at the Institute of Jet Propulsion (ISA) at the Bundeswehr University Munich used a scaled model of a compact double s-shaped intake duct with flow control techniques utilizing air injection and suction for boundary layer control and separation suppression. Detailed total pressure measurements with a Kiel probe rake at the exit plane of the duct show the effectiveness of the individual flow control mechanisms. Suction is applied at three different locations. For each configuration, the suction port diameter and mass flow rate are varied. For tests with injection, air is blown into the intake duct through a Coanda nozzle at two specific positions. The Coanda nozzle slot width and the number of slots were varied. The results demonstrate which parameters must be set to effectively influence the flow and achieve favorable distortion parameters at the intake duct’s outlet.
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Fu, T. C., A. M. Fullerton, E. Terrill, W. Faller, G. Lada, D. Hess, and L. Minnick. "Measurement and Modeling of the Motions of a High-Speed Catamaran in Waves." In ASME 2009 28th International Conference on Ocean, Offshore and Arctic Engineering. ASMEDC, 2009. http://dx.doi.org/10.1115/omae2009-79810.
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Wetdeck slamming can be defined as a large vertical acceleration event that occurs when ship motions cause an impact between the cross deck and the ocean’s surface. The use of Computational Fluid Dynamics (CFD) and other simulation tools to accurately predict wetdeck slamming loads and ship motions has become the objective of a number of efforts (Hess, et al, 2007; Lin, et al, 2007; Faller et al, 2008; for example). The Sea Fighter, FSF-1, is a high-speed research vessel developed by the U.S. Office of Naval Research (ONR). Christened in 2005, she is an aluminum catamaran propelled by four steerable water jets capable of speeds up to 50 knots. In 2006, Sea Fighter underwent a series of rough water trials to assess its operational profile in high sea states (Fu, et. al., 2007). Along with this assessment, ONR sponsored an effort to obtain full-scale qualitative and quantitative wave slamming and ship motion data. One of these rough water trials took place 18–20 April 2006 as the ship transited from Esquimalt, British Columbia, Canada to San Diego, California, USA. During this trial, the significant wave height ranged from 1.5 to 2.7 m and the ship speed ranged from 20 to 40 knots. This paper describes the results of the effort to characterize the Sea Fighter’s motion in waves. To provide suitable full-scale validation data, the incoming ambient waves had to be characterized. A Light Detecting and Ranging, (LiDAR) system, an array of ultrasonic distance sensors, and several video cameras were used to characterize the incoming wave field. In addition, three fiber optic gyro motion units were deployed to record ship motions. Additionally, a GPS unit was utilized to measure ship speed, pitch, roll, and heading. Several slam and near slam events are discussed over the range of ship’s speed, heading, and sea states tested. Similarities and differences between these events are also noted. Additionally, this data was used to develop a simulation of the Sea Fighter’s motion in waves similar to previous work done utilizing model test data (Hess, et al, 2007; Faller et al, 2008).
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Simmons, Kathy, and Graham Johnson. "Velocity Measurements in the Vicinity of the Exit and Inlet of a Spiral Bevel Gear Shroud." In ASME Turbo Expo 2015: Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/gt2015-43549.
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In many aeroengines the accessory power offtake is achieved using a spiral bevel gear set running off one of the main shafts. The crown and bevel gears are housed in an internal gearbox. Over the past few years the Nottingham University Technology Centre (UTC) in Gas Turbine Transmission Systems has researched flow near spiral bevel gears both computationally and experimentally using a purpose-built test rig. In the current investigation the rig was configured with a Trent crown gear and slightly modified shroud covering the full 360° of the gear. No external containment chamber was fitted and all testing was conducted single-phase (air only) at 5,000 rpm. Laser Doppler Anemometry (LDA) was used to obtain the three components of flow velocity at a shroud exit slot and at shroud inlet. A 2D system was utilised and thus two measurements were required at each point to give the 3 velocity components. The LDA technique enabled detailed mapping of flow features over the chosen regions, which included areas very near the shroud surfaces. Data was obtained over two measurement regions: 1) a volume mapping the air “jet” exiting the shroud exit slot at top dead centre (TDC) and 2) an area capturing the flow structures local to the shroud inlet. Combined the results form an excellent set of high quality, detailed, 3-component flow data for direct use in validating CFD models and/or to define CFD boundary conditions. At the shroud exit slot the maximum velocity measured was 46.2 m/s with the jet velocity dispersing over the measurement volume such that by 26 mm from slot plane the maximum velocity was less than 20 m/s. The jet angle was found to be only 16° off perpendicular azimuthally and 22° down from perpendicular. Data from the top 5 slots shows good similarity indicating the detailed data for the TDC slot is probably applicable to all slots. Air entering the shroud comes down the shroud face and up the rotating end face of the gear shaft. The azimuthal velocity component at shroud inlet was around 20 m/s; this is of the order of 50% of the maximum linear shaft surface speed. Within 3 mm of the rotating gear face the azimuthal velocity is less than 1 m/s. Detailed measurements were obtained only at one angular location but sufficient additional measurements were obtained to determine that for the purposes of CFD validation the results can be considered representative.
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Rojatkar, Prachi, Yi-Huan Kao, Milind A. Jog, and San-Mou Jeng. "Effect of Swirler Offset on Aerodynamics of Multiswirler Arrays." In ASME Turbo Expo 2014: Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/gt2014-26236.
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Multiple swirlers arranged in an annular fashion are used in modern day gas turbine engines. A section of this annulus can be considered as a straight line or what is referred to in the paper as a linear arrangement of swirlers. Three such linear arrangements are computationally analyzed and results are presented through this study. Study of linear arrangements is crucial and novel to the swirler aerodynamics research as it lays a foundation in understanding the flow physics when swirlers are arranged at a fixed distance next to each other. Swirling flows are complicated and when slight modifications are introduced in physical arrangements the flow is impacted drastically. In the present study observations have been presented on effect of changing the offset of exit plane of swirler from the base wall of confinement when there is a single swirler or a linear arrangement of swirlers. Computational simulations of flow through single and multi-swirler array have been carried out to understand the effect of the distance of exit plane of swirler from the base wall of confinement on the swirler aerodynamics. The swirlers used in this study are radial-radial swirlers with counter rotating vanes. The computational domain extended from the inlet manifold to 12 D downstream from the swirler where D is the diameter of swirler exit. Realizable k-ε turbulence model is used and the computational grid is about 4 million points for a single swirler arrangement, about 12 million points for a three swirler array and up to 22 million for the five swirler arrangement. The computational model is validated by comparing the results with velocity measurements carried out at three different planes downstream of the swirler exit using LDV technique. First, single swirler with the exit plane of swirler with an offset of 0.04 D and 0.02D with the base wall of confinement and that with no offset (swirler exit in-line with base wall of confinement) are analyzed. It is observed that flow development in region close to the swirler exit is highly sensitive to the offset condition. In case of 0.04D and 0.02D offset a strong jet is formed as soon as the air exits the swirler. The flow tends to progress vertically forming recirculation zones in the vicinity of corners of the horizontal and vertical walls. When there is no offset, the flow exiting the swirler tends to align with the base wall and then progresses vertically. Thus for no offset case a jet formation is not observed. Next, multi-swirler arrangements with 0.04D, 0.02D offset as well as no offset configurations are simulated. All the swirlers tend to show similar pattern as single swirler arrangements with a slight difference in intensity of the flow field. For swirlers with offset of 0.04D and 0.02D there is formation of a strong jet exiting the swirler and recirculation zones are formed in corners of the base and vertical walls of the confinement as was observed for the single swirler arrangement. Recirculation zones are also formed in areas between each swirler assembly in the multi swirler arrangement. For the no offset condition it is again observed that flow aligns with the horizontal base wall for each of the swirler assembly. The axial velocity of the flow in this arrangement tends to be lower than the offset case in regions between each swirler. An interesting phenomenon of multi swirler arrangement is an asymmetrical flow pattern that is observed at each swirler. While each swirler geometry is identical, the flow pattern as well as the strength of recirculation zone developed from each individual swirler differs significantly. Results show that alternate swirlers tend to exhibit similar flow characteristics.