THE JET ENGINE BOOK
It will be noted that the emphasis in this book is on the turbo-jet engine and that no special part deals with the propeller-turbine engine. This is because the. The Jet Engine [Rolls Royce] on ppti.info *FREE* shipping on qualifying offers. The Jet Engine provides a complete, accessible description of the working . This is a very good book for gas turbine engine technology. It is helpful over the whole subject, but having detailed sections of individual engines (really the best .
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Well written book that provides simple, concise, and illustrated description of the principles of Jet engines without having to resort to the use of highly complex. The Jet Engine provides a complete, accessible description of the working book, originally published in under Rolls Royce's own imprint. Buy The Jet Engine 5th by Rolls Royce (ISBN: ) from Amazon's Book Store. Everyday low prices and free delivery on eligible orders.
The hot exhaust gases exit the engine through a tapering exhaust nozzle. So the hot air leaving the engine at the back is traveling over twice the speed of the cold air entering it at the front—and that's what powers the plane. Military jets often have an after burner that squirts fuel into the exhaust jet to produce extra thrust. The backward-moving exhaust gases power the jet forward.
Because the plane is much bigger and heavier than the exhaust gases it produces, the exhaust gases have to zoom backward much faster than the plane's own speed.
In brief, you can see that each main part of the engine does a different thing to the air or fuel mixture passing through: Compressor: Dramatically increases the pressure of the air and, to a lesser extent its temperature. Combustion chamber: Dramatically increases the temperature of the air-fuel mixture by releasing heat energy from the fuel.
Exhaust nozzle: Dramatically increases the velocity of the exhaust gases, so powering the plane. Whittle's engines British engineer Sir Frank Whittle — invented the jet engine in , and here's one of his designs taken from a patent he filed in As you can see, it bears a resemblance to the modern design up above, although it works a little differently most obviously, there is no fan at the inlet.
Briefly, air shoots in through the inlet 1 and is pressurized and accelerated by a compressor 2.
Some is fed to the engine 3 , which drives a second compressor 4 , before exiting through the rear nozzle 5. The rear compressor's exhaust drives the compressor at the front 6.
Artwork: Gas turbine engine designed by Frank Whittle in and formally patented two years later. Drawing taken from US Patent: 2,, Propulsion of aircraft and gas turbines , courtesy of US Patent and Trademark Office, with colors and numbers added for clarity. The patent document explains how this engine works in a lot more detail. Types of jet engines Artwork: A summary of six main types of jet engine.
Each one is explained further in the text below, followed by a link to an excellent NASA website where you'll find even more graphics and animations.
All jet engines and gas turbines work in broadly the same way pulling air through an inlet, compressing it, combusting it with fuel, and allowing the exhaust to expand through a turbine , so they all share five key components: an inlet, a compressor, a combustion chamber, and a turbine arranged in exactly that sequence with a driveshaft running through them. But there the similarities end. Different types of engines have extra components driven by the turbine , the inlets work in different ways, there may be more than one combustion chamber, there might be two or more compressors and multiple turbines.
And the application the job the engine has to do is also very important. Aerospace engines are designed through meticulously engineered compromise: they need to produce maximum power from minimum fuel with maximum efficiency, in other words while being as small, light, and quiet as possible. Gas turbines used on the ground for example, in power plants don't necessarily need to compromise in quite the same way; they don't need to be either small or light, though they certainly still need maximum power and efficiency.
The BA had eight Pratt and Whitney J turbojets, each of which could produce about 10, pounds of thrust. Picture courtesy of US Air Force. Whittle's original design was called a turbojet and it's still widely used in airplanes today.
A turbojet is the simplest kind of jet engine based on a gas turbine: it's a basic "rocket" jet that moves a plane forward by firing a hot jet of exhaust backward. The exhaust leaving the engine is much faster than the cold air entering it—and that's how a turbojet makes its thrust. In a turbojet, all the turbine has to do is power the compressor, so it takes relatively little energy away from the exhaust jet. Turbojets are basic, general-purpose jet engines that produce steady amounts of power all the time, so they're suitable for small, low-speed jet planes that don't have to do anything particularly remarkable like accelerating suddenly or carrying enormous amounts of cargo.
The engine we've explained and illustrated up above is an example. Read more about turbojets from NASA includes an animated engine you can play about with. Turboshafts Photo: The gray tube you can see under the rotor of this US military Seahawk helicopter is one of its twin turboshaft engines.
There's another one exactly the same on the other side. You might not think helicopters are driven by jet engines—they have those huge rotors on top doing all the work—but you'd be wrong: the rotors are powered by one or two gas-turbine engines called turboshafts. A turboshaft is very different from a turbojet, because the exhaust gas produces relatively little thrust. Instead, the turbine in a turbojet captures most of the power and the driveshaft running through it turns a transmission and one or more gearboxes that spin the rotors.
Apart from helicopters, you'll also find turboshaft engines in trains, tanks, and boats. Gas turbine engines mounted in things like power plants are also turboshafts.
Turboprops Photo: A turboprop engine uses a jet engine to power a propeller. A modern plane with a propeller typically uses a turboprop engine. It's similar to the turboshaft in a helicopter but, instead of powering an overhead rotor, the turbine inside it spins a propeller mounted on the front that pushes the plane forward.
Unlike a turboshaft, a turboprop does produce some forward thrust from its exhaust gas, but the majority of the thrust comes from the propeller. Since propeller-driven planes fly more slowly, they waste less energy fighting drag air resistance , and that makes them very efficient for use in workhorse cargo planes and other small, light aircraft. However, propellers themselves create a lot of air resistance, which is one reason why turbofans were developed.
Read more about turboprops from NASA. Turbofans Photo: A turbofan engine produces more thrust using an inner fan and an outer bypass the smaller ring you can see between the inner fan and the outer case.
Each one of these engines produces 43, pounds of thrust almost 4. Giant passenger jets have huge fans mounted on the front, which work like super-efficient propellers. The fans work in two ways. They slightly increase the air that flows through the center core of the engine, producing more thrust with the same fuel which makes them more efficient.
They also blow some of their air around the outside of the main engine, "bypassing" the core completely and producing a backdraft of air like a propeller. In other words, a turbofan produces thrust partly like a turbojet and partly like a turboprop. Low-bypass turbofans send virtually all their air through the core, while high-bypass ones send more air around it. Impressive power and efficiency make turbofans the engines of choice on everything from passenger jets typically using high-bypass to jet fighters low-bypass.
The bypass design also cools a jet engine and makes it quieter. Read more about turbofans from NASA. Jet engines scoop air in at speed so, in theory, if you designed the inlet as a rapidly tapering nozzle, you could make it compress the incoming air automatically, without either a compressor or a turbine to power it.
Engines that work this way are called ramjets, and since they need the air to be traveling fast, are really suitable only for supersonic and hypersonic faster-than-sound planes. Air moving faster than sound as it enters the engine is compressed and slowed down dramatically, to subsonic speeds, mixed with fuel, and ignited by a device called a flame holder, producing a rocket-like exhaust similar to that made by a classic turbojet.
Ramjets tend to be used on rocket and missile engines but since they "breathe" air, they cannot be used in space. Scramjets are similar, except that the supersonic air doesn't slow down anything like as much as it speeds through the engine. By remaining supersonic, the air exits at much higher speed, allowing the plane to go considerably faster than one powered by a ramjet theoretically, up to Mach 15, or 15 times the speed of sound—in the "high hypersonic" region. Read more about ramjets and scramjets from NASA.
Chart: Modern jet engines are about times more powerful than the ones invented by Frank Whittle and his German rival Hans von Ohain. A Scramjet slows the air down to low supersonic speeds and then burn high flame velocity fuels such as hydrogen or methane to try to get net thrust.
Wikipedia has related information at scramjet As the velocity increases the total temperature of the gas stream rises above the dissociation temperature of the combustion products.
This prevents efficient burning if the gas stream is diffused to subsonic speeds. To solve this, fuels with high propagation velocities such as hydrogen are used while diffusing the intake air to supersonic speeds without having a large rise in temperature of the gas stream.
The challenges become one of obtaining stable flame fronts and a net thrust. Turbojet[ edit ] A turbojet adds a rotating compressor powered by a turbine. This allows increased compression beyond the stagnation pressure of the intake and improves the efficiency over a ramjet at lower speeds.
The hot air after it leaves the turbine is accelerated by the nozzle and ejected. An afterburner can be used to augment the thrust.
Turbofan[ edit ] A shrouded fan allows a larger mass of air to be moved by a shrouded fan whose flow bypasses the core. The relative size of the fan compared to the core is identified by the bypass ratio.
Jet Engine theory books
The figure below shows the typical layout of a two shaft high bypass turbofan. The ratio of turbofan bypass mass flow to the engine core mass flow in a turbofan engine. As the name suggests, this is the ratio of the air which bypasses the engine core and flows round the outside of the engine and exits via the nozzle.
Increasing the size of the fan and the bypass ratio causes a weight penalty. Unducted fans or Propfans have reduced weight penalty but the noise has not been acceptable in the west. Geared Turbofan[ edit ] Since the fan is much larger diameter than the turbine it must operate at much lower rpm. Traditionally this is achieved by multiple turbine stages. However this makes the turbine system unnecessarily complex and so gearboxes have been attempted to reduce the number of turbine stages required..
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The power requirements have so far evaded application in larger size turbofans, but companies are still trying. Wikipedia has related information at turboprop Turboshaft with a gearbox and a propeller.
Turboshaft[ edit ] Intake, Compressor, Combustor, and Turbine powering a shaft. Used in helicopters, APUs , as well as surface applications like tanks, ships, electricity generation. Intake closure may be dynamic or with mechanical valves such as reed valves. Turbine Propulsion: A. Turbofan Engines - Large Fan in ahead of compressor-turbine spool s core with By-Pass Cold Airflow Duct around engine body and compressor-turbine spool s core. Turbine Torque: A. Non-Turbine Propulsion Powerplants: A.
Ramjet - Hollow convergent venturi tube, lit off when enough forward airspeed is present to provide the compression needed to light it off. Higher in efficiency and thrust than Propulsion Turbine Powerplants and is dependent on the ability of the fuel injection system pressure and fuel volume delivery limits.
Jet Propulsion/Jet engine types
Ramjets are limited to speeds below where the Nitrogen and Oxygen in the air do not compress to such enormous pressures as to where the Oxygen and Nitrogen merge as one killing combustion. Scramjet - Supersonic Scramjet or "scramjet". These propulsion powerplants are ramjets rated for much higher speeds from supersonic to into hypersonic speeds more than MHP.
The only limitation is what any ramjet needs to overcome: The merger of Oxygen and Nitrogen in the Air under enormous compression, when not controlled will merge the Oxygen and Nitrogen as one and kill combustion.The thrust from one or more engines pushes a plane forward, forcing air past its scientifically shaped wings to create an upward force called lift that powers it into the sky.
Only such description and formulae, therefore, as are necessary to the understanding of the function and the theory of the engine are included. Trivia About The Jet Engine. The Jet Engine by Rolls Royce. It will be noted that the emphasis in this book is on the turbo-jet engine and that no special part deals with the propeller-turbine engine.
No rotating machinery is used and compression is achieved by the intake and diffuser. Mohammed Nasser marked it as to-read May 21, Approach the design and testing process with caution and take appropriate safety measures i.