An air-breathing engine is an engine that takes in air from its surroundings in order to burn fuel. All practical air breathing engines are internal combustion engines that directly heat the air by burning fuel, with the resultant hot gases used for propulsion via a propulsive nozzle. A continuous stream of air flows through the air-breathing engine. The air is compressed, mixed with fuel, ignited and expelled as the exhaust gas. Thrust produced by a typical air-breathing engine is about eight times greater than its weight. The thrust results from the expulsion of the working gases from the exhaust nozzle. To expel the gases from the nozzle at high velocity, the air entering the combustion chamber of the engine is compressed. A) Turbine powered Turbine powered engines uses turbo machinery to compress incoming air and produce sufficient thrust to propel the vehicle. Gas turbines are the typical turbine powered engines. There are many different variations of gas turbines, but they all use a gas generator system of some type. Gas Generator Gas generator is the heart of the gas turbine engine. The compressor, combustor and turbine are the major components of the gas generator which is common to the turbojet, turbofan and turbo prop engine. The purpose of the gas generator is to provide high temperature and high pressure gas. It is also called core of the engine.. A1) Turbojet Turbojets consist of an inlet, a compressor, a combustor, a turbine (that drives the compressor) and a propelling nozzle. The compressed air is heated in the combustor and passes through the turbine, and then expands in the nozzle to produce a high speed propelling jet. The compressor is powered by the turbine, which extracts energy from the expanding gas passing through it. The engine converts internal energy in the fuel to kinetic energy in the exhaust, producing thrust. Turbojets have a low propulsive efficiency below about Mach 2 and produce a lot of jet noise, both a result of the very high velocity of the exhaust. Modern jet propelled aircraft are powered by turbofans. What happens to the air that passes through the engine? Large amounts of surrounding air are continuously brought into the engine intake. Intakes come in many shapes and sizes depending on the aircraft's mission. At the rear of the inlet, the air enters the compressor. The compressor acts like many rows of airfoils, with each row producing a small jump in pressure. A compressor is like an electric fan. We have to supply energy to turn the compressor. At the exit of the compressor, the air is at a much higher pressure than free stream. In the burner a small amount of fuel is combined with the air and ignited. (In a typical jet engine, 100 pounds of air/sec is combined with only 2 pounds of fuel/sec. Most of the hot exhaust has come from the surrounding air.) Leaving the burner, the hot exhaust is passed through the turbine. The turbine works like a windmill. Instead of needing energy to turn the blades to make the air flow, the turbine extracts energy from a flow of gas by making the blades spin in the flow. In a jet engine we use the energy extracted by the turbine to turn the compressor by linking the compressor and the turbine by the central shaft. The turbine takes some energy out of the hot exhaust, but there is enough energy left over to provide thrust to the jet engine by increasing the velocity through the nozzle. Because the exit velocity is greater than the free stream velocity. A2) Turbofan How does a turbofan engine work? The incoming air is captured by the engine inlet. Some of the incoming air passes through the fan and continues on into the core compressor and then the burner, where it is mixed with fuel and combustion occurs. The hot exhaust passes through the core and fan turbines and then out the nozzle, as in a basic turbojet. The rest of the incoming air passes through the fan and bypasses, or goes around the engine. The air that goes through the fan has a velocity that is slightly increased from free stream. So a turbofan gets some of its thrust from the core and some of its thrust from the fan. The ratio of the air that goes around the engine to the air that goes through the core is called the bypass ratio. Turbofan engines are more efficient than turbojets because of the additional thrust form bypass and fan. How does a turbofan engine work? The incoming air is captured by the engine inlet. Some of the incoming air passes through the fan and continues on into the core compressor and then the burner, where it is mixed with fuel and combustion occurs. The hot exhaust passes through the core and fan turbines and then out the nozzle, as in a basic turbojet. The rest of the incoming air passes through the fan and bypasses, or goes around the engine. The air that goes through the fan has a velocity that is slightly increased from free stream. So a turbofan gets some of its thrust from the core and some of its thrust from the fan. The ratio of the air that goes around the engine to the air that goes through the core is called the bypass ratio. Turbofan engines are more efficient than turbojets because of the additional thrust form bypass and fan. A3) Turboprop Many low speed transport aircraft and small commuter aircraft use turboprop propulsion. The turboprop uses a gas turbine core to turn a propeller. Propeller engines develop thrust by moving a large mass of air through a small change in velocity. Propellers are very efficient and can use nearly any kind of engine to turn the prop (including humans!). In the turboprop, a gas turbine core is used. How does a turboprop engine work? There are two main parts to a turboprop propulsion system, the core engine and the propeller. The core is very similar to a basic turbojet except that instead of expanding all the hot exhaust through the nozzle to produce thrust, most of the energy of the exhaust is used to turn the turbine. There may be an additional turbine stage present which is connected to a drive shaft. The drive shaft (shown in green) is connected to a gear box. The gear box is then connected to a propeller that produces most of the thrust. The exhaust velocity of a turboprop is low and contributes little thrust because most of the energy of the core exhaust has gone into turning the drive shaft. Because propellers become less efficient as the speed of the aircraft increases, turboprops are used only for low speed aircraft like cargo planes. High speed transports usually use high bypass turbofans because of the high fuel efficiency and high speed capability of turbofans. A variation of the turboprop engine is the turboshaft engine. In a turboshaft engine, the gear box is not connected to a propeller but to some other drive device. Turboshaft engines are used in many helicopters, as well as tanks, boats, and even race cars B) Ram powered Ram powered jet engines are air-breathing engines similar to gas turbine engines. Ram powered engines and turbine powered engines are differed in compressing techniques used to compress in-coming air. Turbine engines used turbo machinery to compress the air where as ram engines uses kinetic energy of the incoming air and the geometry of the air intake to compress air. Ram powered engines are considered the simplest type of air breathing jet engine because they don’t have any moving parts. B1) Ramjets Ramjets are the most basic type of ram powered jet engines. A ramjet engine provides a simple, light propulsion system for high speed flight. They are mainly used in supersonic missiles. They consist of three sections; an inlet to compress incoming air, a combustor to inject and combust fuel, and a nozzle to expel the hot gases and produce thrust. Ramjets require a relatively high speed to efficiently compress the incoming air, so ramjets cannot operate at a standstill and they are most efficient at supersonic speeds. A key trait of ramjet engines is that combustion is done at subsonic speeds. The name ramjet comes from the way of air compression done by the inlet, which collects and compresses, or rams, the incoming air flow to the isolator[The transition from supersonic to subsonic flow occurs in the isolator section through a complex shock-train interaction with the wall boundary layer] and from there on to the combustor. By doing this, the air flow velocity decreases dramatically from supersonic to subsonic speeds by means of a normal shock system inside the isolator, and produces ram pressure and an increase in temperature of the air flow. In the fixed area combustor (consisting of a fuel injector and flame holder), heat and mass is added, through injection, mixing and burning of fuel with the incoming air flow. And finally the nozzle converts a portion of the energy of the outgoing combustion flow to kinetic energy to produce thrust. This is done by accelerating the flow and the reaction to this acceleration produces the thrust, as is explained by Newton's Third Law. Ramjets can be classified according to the type of fuel, liquid or solid; and the booster. B2) Scramjets A scramjet engine is an improvement over the ramjet engine as it efficiently operates at hypersonic speeds and allows supersonic combustion. Thus it is known as Supersonic Combustion Ramjet, or Scramjet. As in ramjets, a scramjet relies on high vehicle speed to forcefully compress and decelerate the incoming air before combustion (hence jet), but whereas a ramjet decelerates the air to subsonic velocities before combustion, airflow in a scramjet is supersonic throughout the entire engine. This allows the scramjet to operate efficiently at extremely high speeds: theoretical projections place the top speed of a scramjet between Mach 12 and Mach 24. A dual-mode scramjet (DMSJ) is a fixed geometry air-breathing engine the DMSJ is composed of four main sections. The inlet captures the air-mass, the isolator separates combustion effects from the inlet, the combustor introduces, mixes, and burns the fuel-air mixture, and the exit nozzle expands the exhaust gases to produce vehicle thrust1 . The DMSJ requires no mechanical compressor, but instead utilizes external and internal shock structures to achieve inlet air compression. This means that the DMSJ is only able to operate at supersonic speeds, which may be initially achieved via a rocket or turbine based systems C) Combined cycle Air augmented Rocket - It represents a hybrid class of rocket/ramjet engines, similar to a ramjet, but able to give useful thrust from zero speed, and is also able in some cases to operate outside the atmosphere, with fuel efficiency not worse than both a comparable ramjet or rocket at every point. This kind of propulsion use the supersonic exhaust of some kind of rocket engine to further compress air collected by ram effect during flight to use as additional working mass, leading to greater effective thrust for any given amount of fuel than either the rocket or a ramjet alone. Air turboramjet engine - The air turboramjet engine is a combined cycle engine that merges aspects-of turbojet and ramjet engines. The turboramjet is a hybrid engine that essentially consists of a turbojet mounted inside a ramjet. The turbojet core is mounted inside a duct that contains a combustion chamber downstream of the turbojet nozzle. The turbo-ramjet can be run in turbojet mode at takeoff and during low speed flight but then switch to ramjet mode to accelerate to high Mach numbers. The operation of the engine is controlled using bypass flaps located just downstream of the diffuser. During low speed flight, controllable flaps close the bypass duct and force air directly into the compressor section of the turbojet. During high speed flight, the flaps block the flow into the turbojet, and the engine operates like a ramjet using the AFT combustion chamber to produce thrust. The engine would start out operating as a turbojet during takeoff and while climbing to altitude. Upon reaching high subsonic speed, the portion of the engine downstream of the turbojet would be used as an afterburner to accelerate the plane above the speed of sound. The turboramjet engine is used when space is constrained, as it takes up less space than separate ramjet and turbojet engines Courtesy ISRO Grc.nasa.gov.in Wikipedia nasa Different Reference text books 1/5/2018 06:05:06 pm
Technology Submission - Featured Project Development: State of the Art Novel InFlowTech 1-Gearturbine RotaryTurbo, 2-Imploturbocompressor One CompressionStep: |/ *1; Gearturbine Project, Rotary Turbo, Have the similar basic system of the Aeolipilie Heron Steam Turbine device from Alexandria 10-70 AD · With Retrodynamic = DextroRPM VS LevoInFlow + Ying Yang Way Power Type - Non Waste Looses · 8X/Y Thermodynamic CYCLE Way Steps. 4 Turbos, Higher efficient percent. No blade erosion by sand & very low heat target signature Pat:197187IMPI MX Dic1991 Atypical Motor Engine Type. |/ *2; Imploturbocompressor; One Moving Part System Excellence Design - The InFlow Interaction comes from Macro-Flow and goes to Micro-Flow by Implossion - Only One Compression Step; Inflow, Compression and outflow at one simple circular dynamic motion / New Concept. To see a Imploturbocompressor animation, is possible on a simple way, just to check an Hurricane Satellite view, and is the same implo inflow way nature. http://stateoftheartnovelinflowtech.blogspot.mx/
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Khan Gach
10/30/2023 01:56:05 pm
Wow it was so nice Sir and stay bless!!!!!
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