Scramjets are an evolution of the ramjet that are able to operate at much higher speeds than ramjets (or any other kind of airbreathing engine) are capable of reaching. They share a similar structure with ramjets, being a specially-shaped tube that compresses air with no moving parts through ram-air compression. Scramjets, however, operate with supersonic airflow through the entire engine. Thus, scramjets do not have the diffuser required by ramjets to slow the incoming airflow to subsonic speeds.
Scramjets start working at speeds of at least Mach 4, and have a theoretical maximum speed of Mach 17. Due to aerodynamic heating at these high speeds, scramjets are expected to be very heavy. Cooling, as a result, poses a challenge to engineers.
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Come lets know more about jet engines
JET ENGINE
How does a jet engine work?
A jet engine uses a gas turbine to drive a fan that sucks in air, mixes it with burning fuel, and then blasts the expanded air-gas mixture out the back.
Because every action has an equal and opposite reaction, as the air streams backward the engine is forced forward.
turbine
Safety and reliability
Jet engines are usually very reliable and have a very good safety record. However failures do sometimes occur.The most likely failure is compressor blade failure, and modern jet engines are designed with structures that can catch these blades and keep them contained them within the engine casing. Verification of a jet engine design involves testing that this system works correctly.
model jet engine
combustion chamber
diagrams
In order to understand how an engine works..
we first need to understand the process of combustion. Combustion is defined as the burning, or oxidation, of matter to produce energy. Two substances are necessary for combustion to occur--a fuel and an oxidizer. A fuel can be anything from the wood, coal, or natural gas used to produce heat in a furnace to gasoline or hydrogen used in an internal combustion engine. An oxidizer, as its name implies, is a substance that contains oxygen.
The purpose of both the jet engine and the rocket engine is to combust a mixture of fuel and oxidizer. This combustion process generates a high-pressure exhaust that creates thrust to push a vehicle forward. The fundamental difference between the two types of engines, however, is where the oxidizer comes from.
A jet engine obtains its oxidizer from the external atmosphere, as illustrated in the diagram below. Air enters the engine through an inlet and is then slowed down and compressed by a series of compressor blades. The compressed air is then mixed with fuel, typically a petroleum-based liquid similar to kerosene, and burned. The high-pressure gas is exhausted through a nozzle to generate thrust.
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