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Internal combustion engines and fuels
Published in J. F. Griffiths, J. A. Barnard, Flame and Combustion, 2019
J. F. Griffiths, J. A. Barnard
In these engines, air is first compressed and then fuel is injected and burned continuously in a combustion chamber. The burned gas at high pressure and temperature then provides the energy source. The propulsion of a turbojet is gained from the thrust at the exhaust, which is generated by increasing the momentum of the fluid passing through the engine. The exhaust nozzle has an extremely important function in accelerating the fluid to high velocity. The sole function of the turbine is to drive the air compressor which, in the simplest design, is a single spool system; the turbine downstream from the combustion chamber drives the upstream, air compressor (Fig. 13.3). Propulsion by a turboprop aircraft engine relies on an independent power turbine to drive a propeller. The power turbine is driven by the high velocity, combustion exhaust gases and is capable of rotating at different speeds from the compressor/turbine shaft. In industrial and marine gas turbine applications the power turbine follows the turbojet type of compressor/burner/turbine combination. Some industrial and marine gas engines are derived from turbojets.
Turn performance and flight maneuvers
Published in Mohammad H. Sadraey, Aircraft Performance, 2017
This section and Section 9.4 are devoted to the analysis of the turn performance for both jet and prop-driven aircraft. They cover the aircraft requirements to perform a level turn with a desired turn radius and turn rate. The type of aircraft engine will influence the aircraft turn performance in various aspects. Aircraft engines are divided into several groups, two of which are jet (e.g., turbofan and turbojet) and prop-driven (e.g., turboprop and piston-prop). This section presents the turn performance for a jet aircraft, while Section 9.4 presents the turn performance for a prop-driven aircraft. Two main unknown parameters to perform a level turn are engine thrust and engine power.
Influences of cryogenic CO2 and LN2 on surface integrity of inconel 625 during face milling
Published in Materials and Manufacturing Processes, 2021
In general, nickel alloys have an ability to retain their strength even at extremely high temperatures. Therefore, it is the only choice of metal used in parts of the gas turbine or aircraft engine. The difficulties faced by manufacturing industries during milling of nickel alloys are due to their poor thermal conductivity, work–hardening behavior and adhesion of chips onto the cutting tool. These unfavorable characteristics create an excessive cutting tool wear and also produce end product with poor surface integrity index.[2] In addition, a heavy thermo-mechanical load is experienced by the cutting inserts during milling of nickel alloys. For that reason, well-designed lubrication and cooling techniques are required to trim down friction and to lessen cutting temperature. Moreover, the lubricant or coolant is used during the milling operation to avoid excessive cutting tool wear, cutting zone temperature, cut surface damage and cutting forces, which improves surface integrity. Wet/flood coolant is often preferred by metal cutting industries for lubrication and cooling of milling processes. However, it has a lot of harmful effects on the machinist and environment. In addition, it also adds up to high cost due to cleaning, disposal of chip, treatment and extraction of coolant.[3] At present, cryogenic coolants replace standard industrial-based wet/flood coolant in metal cutting industries. The liquid CO2 and LN2 are commonly used cryogenic coolants which improve the machinability or cutting of hard-to-cut metals.[4]
Exergo-sustainability behavior of high by-pass turbofan engine of a passenger aircraft during main flight phases
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2021
Sustainability analysis plays a key role in the evaluation of the environmental performance of propulsion systems. To provide more realistic outcomes, effects of flight phases should be involved for analysis. Moreover, realized possibilities or advantages from exergy analysis should be evaluated with economic analysis. This effort allows us to determine the proper trade-off between improvement potential and costs. Also, based on exergy approach, life cycle assessment for the propulsion system could allow to mitigate environmental damage from the aircraft engine. As next study, optimization flight conditions could be researched so as to find out minimum environmental effect by employing meta-heuristics approaches. Furthermore, exergo-economic and advance exergy methods could be implemented over the course of flight phases. Finally, emission analysis such as NOx and CO2 for PW4000 engine could be performed at cruise phase.
Multicriteria decision and sensitivity analysis support for optimal airport site locations in Ordu Province, Turkey
Published in Annals of GIS, 2023
H. Ebru Çolak, Tuğba Memişoğlu Baykal, Nihal Genç
One environmental factor that has great importance in airport site selection is noise. Noise from the aircraft engine harms the environment. With the increasing air transportation in the developing world, aircraft development with more powerful engines has brought along the noise problem. It can also cause problems such as headaches and hearing loss. It makes communication, rest, and sleep difficult; causes restlessness, sleep disorders, and psychological problems. The reasons such as taking care of public health, which has been adopted more and more with the increasing awareness of the society over the years, also make noise an essential factor. It is also considered in the land use plan of properties located in or around the airport land area (ICAO 1987).