File Name: design and construction of aircraft gas turbine engine .zip
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You must log in to edit PetroWiki. Help with editing. Content of PetroWiki is intended for personal use only and to supplement, not replace, engineering judgment. SPE disclaims any and all liability for your use of such content. More information. This page focuses on the gas turbine engine, the differences between types of turbines, and items to consider when they are applied as the prime mover.
As shown in Fig. This cycle consists of:. The heated air is expanded through the gas producer turbine section between Points 3 and 5 , where the energy of the working fluid is extracted to generate power for driving the compressor, and expanded through the power turbine to drive the load Point 7. The air is then exhausted to the atmosphere. A starting system is used to get the air compressor up to sufficient speed to supply air for combustion with the fuel injected into the combustor.
The output power of a gas turbine may be increased by increasing the maximum cycle temperature. The maximum cycle temperature is designated TRIT, which stands for turbine rotor inlet temperature. TRIT is calculated immediately upstream of the first-stage turbine rotor and includes the calculated effects of cooling air and temperature drop across the first-stage stator vanes. The output power of a gas turbine may also be increased by increasing the mass flow of air through the gas turbine.
The geometry of the gas turbine, particularly the compressor, and the speed of the compressor dictate basic air mass flow. An increase in flow requires an increase in speed, which is limited to the maximum continuous running speed of any particular design.
At a given speed, an increase in inlet air density increases air mass flow. Inlet air density increases directly with barometric pressure and inversely with ambient temperature. Increasing any one of these parameters increases the output power capacity of the gas turbine. Speed and temperature may be dictated by the output power and heat rate desired within the constraints imposed by the following factors:.
As the speed of a gas turbine increases, the centrifugal forces on the rotating components increase. These forces increase the stress on the rotating components, particularly the following:. Component materials have stress limits that are directly proportional to their speed limits and should not be exceeded. Thus, the maximum continuous speed of the rotating element is a function of:.
One way to increase output power is to increase the fuel flow and therefore TRIT. As TRIT increases, hot section components operate at higher metal temperatures, which reduces the time between inspection TBI of the gas turbine. Because the life of hot section materials is limited by stress at high temperature, there are limitations on the maximum temperatures for a given TBI. Material life decreases rapidly at higher temperatures. The creep or stress rupture limit is established by the material properties as a function of their stress level and operating temperature.
A rating point can be established for determining gas turbine performance for specified ambient conditions, duct losses, fuel, etc. This has become a standard rating point for comparing turbines of various manufacturers and designs. The site rating is a statement of the basic gas turbine performance under specific site conditions, including:.
For instance, an increase in ambient temperature reduces output power at a rate influenced by gas turbine design. Most of the mechanical energy extracted from the gas stream by the turbine is required to drive the air compressor, with the remainder available to drive a mechanical load.
The gas stream energy not extracted by the turbine is rejected to the atmosphere as heat. In the recuperative cycle, also called a regenerative cycle, the compressor discharge air is preheated in a heat exchanger or recuperator, the heat source of which is the gas turbine exhaust.
The energy transferred from the exhaust reduces the amount of energy that must be added by the fuel. In Fig. The three primary designs used in stationary recuperators are the:. Adding a steam bottoming cycle to the Brayton cycle uses the exhaust heat to produce additional horsepower, which can be used in a common load, as shown in Fig.
The shaded area represents the additional energy input. Inlet Air Filtration. The quality of air entering the gas turbine is a very important design consideration. Turbine efficiency will decrease over time because of deposits building up on the turbine internal flow path and rotating blades.
This buildup results in increased maintenance and fuel consumption. Selecting and maintaining the proper inlet air filtration system for the specific site conditions will affect the rate of decrease of efficiency over time. It is critical to minimize the pressure drop of the air passing through the: Inlet ducting Inlet air filter Inlet silencer see Noise Attenuation below.
Pressure loss on the atmospheric air entering the turbine greatly affects the performance of the gas turbine. The noise produced by a gas turbine is primarily in the higher-frequency ranges, which are not transmitted as far as the lower-frequency noises produced by slower-speed prime movers such as reciprocating engines. Most high-frequency noise produced by the turbine is generated in the air inlet, with a smaller amount coming from the exhaust. The sources of noise and method of attenuation are as follows:.
The inlet silencer should be specifically designed to the noise profile of the gas turbine and the site requirements. This silencer is installed in the air inlet ducting between the air filter and the turbine air compressor inlet. The exhaust silencer should be specifically designed to the noise profile of the gas turbine and the site requirements. The exhaust stack height in conjunction with the silencer is an important consideration.
Discharging the hot exhaust gases as high as practical reduces the measurable noise at ground level plus has the added benefit of reducing the chance of recirculation of the hot exhaust back into the air inlet. Pressure loss backpressure on the exhaust of the turbine greatly affects the performance of the gas turbine. Sound-attenuating enclosure s can be installed directly over the equipment such as skid-mounted walk-in enclosures or a building containing the equipment insulated to meet the requirements or both.
These generate fan noise that can be controlled with fan tip speed. The use of shell and tube water coolers can be noise-efficient if the cooling media is available. Aircraft turbine engines or jet engines are designed with highly sophisticated construction for light weight specifically for powering aircraft. These designs require maximum horsepower or thrust with minimum weight and maximum fuel efficiency.
Aircraft turbines have roller bearings and high firing temperatures requiring exotic metallurgy. They can be operated on a limited variation of fuels.
When a jet engine is used in an industrial application, it must be coupled with an independent power turbine to produce shaft power. The basic design parameters for heavy industrial gas turbine engines evolved from industrial steam turbines that have slower speeds, heavy rotors, and larger cases than jet engines to ensure longer life. These gas turbines are capable of burning the widest range of liquid or gas fuels.
The basic design parameters and technology used in aircraft turbines can be combined with some of the design aspects of heavy industrial gas turbines to produce a lighter-weight industrial turbine with a life approaching that of a heavy industrial gas turbine.
These engines are called light industrial gas turbine engines. This combustor surrounds the gas turbine rotating parts and is integral to the engine casing Fig. Aircraft turbines and light industrial gas turbines use this design. This is a single- or multi-combustion system that is separated from the rotating turbine as external combustion cans Fig. Designs using this type of combustor can burn a wider range of fuels.
The gas turbine can have either a single-shaft or a two-shaft design. The single-shaft design consists of one shaft connecting the air compressor, gas producer turbine, and power turbine as one rotating element Fig. This design is best suited for constant-speed applications such as driving electric generators for a constant frequency.
The two-shaft design has the air compressor and gas producer on one shaft and the power turbine on a second independent shaft. This design provides the speed flexibility needed to cover a wider performance map of the driven equipment more efficiently.
This allows the gas producer to operate at the speed necessary to develop the horsepower required by the driven equipment such as centrifugal compressors or pumps. Major components include the compressor, combustion system, gas producer turbine, and power turbine. This design includes a two-stage gas producer turbine and a two-stage power turbine. This includes such systems as the:. Additional operationally required systems are all generally separate pre-engineered packaged systems that can be provided and customized by the turbine manufacturer.
Included in this category are systems such as:. Deterioration of the atmosphere by gaseous pollutants is an important environmental issue. The gas turbine by basic cycle design gives a cleaner combustion and produces a lower level of pollutant compared with other prime movers, which is a major advantage. The gas turbine pollutants that typically are regulated are:.
The solution to some, but not all, of these pollution problems lies within the gas turbine combustor. A brief discussion follows. Almost all emission concerns involving prime movers relate to NO x production and NO x controls. The gas turbine is relatively clean compared with other prime movers. For example, gas turbines burning natural gas generally produce 4 to 12 times less NOx per unit of power than reciprocating engines produce. However, NOx is the major factor in permitting gas turbine installations.
CO is also at a very low level in turbine exhaust because of the excess air in the combustion process. Therefore, it is usually not a problem. However, in some areas where the ambient level of CO is extremely high or when water injection is being used for NO x control in the gas turbine, CO may be a factor in obtaining permits. Unlike reciprocating engines that produce a significant amount of UHC, gas turbines produce a low amount of UHC because the large amount of excess air involved in the gas turbine combustion process completely combusts almost all the hydrocarbons.
Consequently, UHC emissions are rarely a significant factor in obtaining environmental permits for gas turbines.
Early gas turbines employed centrifugal compressors , which are relatively simple and inexpensive. They are, however, limited to low pressure ratios and cannot match the efficiencies of modern axial-flow compressors. Accordingly, centrifugal compressors are used today primarily in small industrial units. An axial-flow compressor is the reverse of a reaction turbine. The blade passages, which look like twisted, highly curved airfoils, must exert a tangential force on the fluid with the pressures on one side of the blade higher than on the other. For subsonic flow, an increase in pressure requires the flow area to also increase, thus reducing the flow velocity between the blade passages and diffusing the flow.
The combustion gas turbines being installed in many of today's natural-gas-fueled power plants are complex machines, but they basically involve three main sections:. Land based gas turbines are of two types: 1 heavy frame engines and 2 aeroderivative engines. Heavy frame engines are characterized by lower pressure ratios typically below 20 and tend to be physically large. Pressure ratio is the ratio of the compressor discharge pressure and the inlet air pressure.
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This article briefly describes the components and systems found in jet engines. The various components named above have constraints on how they are put together to generate the most efficiency or performance. For the engine optimisation for its intended use, important here is air intake design, overall size, number of compressor stages sets of blades , fuel type, number of exhaust stages, metallurgy of components, amount of bypass air used, where the bypass air is introduced, and many other factors. For instance, consider design of the air intake. Intakes are more commonly referred to as inlets in the U. Pitot inlets are used for subsonic aircraft.
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March Gas turbines are widely used throughout the chemical process industries CPI because they allow for high power output and high overall efficiency at relatively reasonable costs. In recent years, a variety of factors and ongoing technology advances have contributed to the continuing evolution of the gas turbine systems. These include the following:. The gas turbine business is a dynamic market with new designs introduced during each decade. The packaging of a gas turbine is the practice of combining and integrating machineries and components for specific application and plant settings.
Scottsdale, Arizona, USA. June 24—26, The purpose of designing and constructing this engine is to investigate the application of hybrid and alternative combustion systems as applied to gas turbine engines used for aircraft propulsion. The interest in this type of system comes from undesirable performance of gas turbine engines at extreme altitudes. The engine is a high-bypass, two-spooled turbofan with the inner spool and combustion system located on the outside of the fan bypass duct.
Стратмору нужен был козел отпущения. Кроме всего прочего, Хейл был настоящим ходячим несчастьем, готовым свалиться на голову в любую минуту. Из задумчивости Стратмора вывел звонок мобильного телефона, едва слышный в завывании сирен и свисте пара. Не останавливаясь, он отстегнул телефон от брючного ремня. - Говорите.
Пока ничего, сэр. Кажется, придется повозиться дольше, чем ожидалось, - это был звонок с мобильника. С мобильника, - мысленно повторил Нуматака. - Это кое-что. К счастью для японской экономики, у американцев оказался ненасытный аппетит к электронным новинкам.
Если Стратмор не забил тревогу, то зачем тревожиться. - Да в шифровалке темно как в аду, черт тебя дери. - Может быть, Стратмор решил посмотреть на звезды. - Джабба, мне не до шуток.
- Поддержи. Коммандер глубоко вздохнул и подошел к раздвижной стеклянной двери. Кнопка на полу привела ее в движение, и дверь, издав шипящий звук, отъехала в сторону. Чатрукьян ввалился в комнату. - Коммандер… сэр, я… извините за беспокойство, но монитор… я запустил антивирус и… - Фил, Фил, - нехарактерным для него ласковым тоном сказал Стратмор.