Jet Classification - PDF

JET CLASSIFICATION WHAT IS PROPULSION derived from two Latin words: pro meaning before or forwards and pellere meaning to drive act of changing the motion of a body with respect to an inertial reference frame push forward or drive an object forward Newton’s third law of motion Ma...

JET CLASSIFICATION WHAT IS PROPULSION derived from two Latin words: pro meaning before or forwards and pellere meaning to drive act of changing the motion of a body with respect to an inertial reference frame push forward or drive an object forward Newton’s third law of motion Matter is forcefully ejected from a system, producing an equal and opposite reaction on what remains Jet propulsion is a type of motion whereby a reaction force is imparted to a vehicle by the momentum of ejected 2 matter (gas or liquid) at high speeds. AIR BREATHING PROPULSION SYSTEMS AKA “duct jet propulsion” comprises devices which entrain and energize airflow inside a duct. push forward or drive an object forward They use atmospheric oxygen to burn fuel stored in the flight vehicle 3 TURBOJET The turbojet is the most widely used air-breathing propulsion system. After the air is drawn into the engine through an inlet, its pressure is first increased by a component called a compressor. The air then enters the combustion chamber, where it is burned with fuel to increase its temperature. 4 TURBOJET The hot, high-pressure gas then expands through a wheel-like device called a turbine, where it produces power. The turbine is connected to the compressor by a shaft, and the power output of the turbine drives the compressor. At the turbine outlet the hot-gas pressure is still above that of the surroundings, and the final expansion takes place 5 through an exhaust nozzle where AXIAL AND CENTRIFUGAL COMPRESSORS In an axial compressor, gas flows parallel to the axis, passing through multiple stages of rotating and stationary blades, which allows for high flow rates and efficiency in large-scale applications like jet engines. 6 AXIAL AND CENTRIFUGAL COMPRESSORS Axial compressors are ideal for high-flow, high-pressure situations but require more stages to achieve desired pressure ratios, making them larger and more complex. 7 AXIAL AND CENTRIFUGAL COMPRESSORS Centrifugal compressors, on the other hand, achieve higher pressure per stage and are effective in smaller systems with moderate flow and pressure needs, such as turbochargers and refrigeration systems. 8 TURBOPROP a conventional aircraft propeller is usually mounted in front of the jet engine and in one type of engine is driven by a second, or free, turbine. This is located behind the turbine that is driving the compressor. In other designs the power is obtained by additional stages on the main turbine. 9 TURBOPROP Turboprops are advantageous for small- and medium-sized planes and at air speeds from 300to 400 miles (480 to 640 kilometers) per hour. They cannot compete with turbojets for very largeplanes or at higher speeds. 10 TURBOFAN combine the best of both worlds between turbojets and turboprops as it employs a duct fan located at its inlet. The duct fan in front creates additional thrust, helps cool the engine, and lowers the noise output of the engine. 11 TURBOFAN the air taken in by the inlet is divided into two separate streams. One stream, flows around the engine, also known as bypass air, while the other passes through the engine’s center. The bypass air that flows around the engine is accelerated by theduct fan, therefore producing additional thrust. 12 RAMJET variant of an air breathing jet engine that does not include a rotary compressor; rather, it uses the engine’s forward motion to compress the incoming air. The air into which an engine rushes at high flight speeds is partially compressed by the so-called ram effect. 13 RAMJET A ramjet cannot function at zero airspeed and therefore cannot be used to power an aircraft in all phases of flight A ramjet equipped aircraft requires another type of propulsion to accelerate it to a speed at which the ramjet is capable of producing thrust. The combustion that produces thrust in the ramjet occurs 14 at a subsonic speed in the SCRAMJET For a vehicle traveling supersonically, the air entering the engine must be slowed to subsonic speeds by the aircraft inlet. Shock waves present in the inlet cause performance losses for the propulsion system. Above Mach 5, ramjet propulsion becomes very inefficient. The new supersonic combustion ramjet, or scramjet, solves this problem by performing 15 the combustion supersonically in PULSEJET a type of jet engine that operates on the principle of intermittent combustion, generating thrust through a series of rapid explosions or “pulses.” Unlike continuous combustion engines like turbojets, pulsejets burn fuel in pulses, which create shock waves that propel the engine forward. The engine consists of a combustion chamber and a simple exhaust pipe with minimal 16 moving parts. NON-AIR BREATHING PROPULSION SYSTEMS AKA “Rocket Propulsion” class of jet propulsion that produces thrust by ejecting matter, called the working fluid or propellant, stored entirely in the flying vehicle. The energy source most commonly used in rocket propulsion is chemical combustion. 17 CHEMICAL ROCKET PROPULSION is a propulsion in which the thrust is provided by the product of a chemical reaction, usually burning (or oxidizing) a fuel. Energy from the combustion reaction of chemical propellants, usually a fuel and an oxidizer, ina high-pressure chamber goes into heating reaction product gases to high temperatures (typically2500 to 4100 ∘C or 4500 to 7400 ∘F). 18 CHEMICAL ROCKET PROPULSION Chemical rocket propulsion systems are classified into two general types according to whether they burn propellants stored as solid or as liquid. Solid systems are usually called motors. liquid systems are referred to as engines 19 CHEMICAL ROCKET PROPULSION Liquid propellant rocket engines use propellants stored as liquids that are fed under pressure from tanks into a thrust chamber. Sub classifications: mono and bipropellant The common liquid rocket is bipropellant; it uses two separate propellants, a liquid fuel and liquid oxidizer. These are contained in separate tanks and are mixed only upon injection into the combustion chamber 20 CHEMICAL ROCKET PROPULSION Certain liquid chemicals can be made to form hot gas for thrust production by decomposition in a rocket chamber, such are monopropellants. The most common such monopropellant is hydrogen peroxide. The common liquid rocket is bipropellant; it uses two separate propellants, a liquid fuel and liquid oxidizer. These are contained in separate tanks and are mixed only upon injection into the combustion chamber 21 CHEMICAL ROCKET PROPULSION In solid propellant rocket motors, the ingredients to be burned are already stored within a combustion chamber or a case.. In the solid-chemical rocket, the fuel and oxidizer are intimately mixed together and cast into a solid mass, called a grain, and it contains all the chemical elements for complete burning. Solid propellant motors have simple construction when compared to its liquid counterparts therefore eliminating the need for feed systems and valves. 22 CHEMICAL ROCKET PROPULSION Gaseous propellant rocket engines use a stored high- pressure gas, such as air, nitrogen, or helium, as working fluid. Such stored gases require relatively heavy tanks. These cold gas thrusters were used in many early space vehicles for low-thrust maneuvers and for attitude-control systems and some are still used today. 23 CHEMICAL ROCKET PROPULSION Hybrid propellant rocket propulsion systems employ both liquid and solid propellant storage. Most frequent for such combination is to have the oxidizer in a liquid state and the fuel in solid state.Listed below are the following types of hybrid propellant combinations that exist. Classic hybrid propellant mixture: liquid oxidizer - solid fuel Inverse hybrid propellant mixture: solid oxidizer - liquid fuel Quasi-hybrid propellant mixture: liquid oxidizer - fuel rich solid propellant Inverse hybrid propellant mixture: oxygen rich solid propellant - liquid 24 fuel NUCLEAR ROCKET ENGINES These are basically a type of liquid propellant rocket engine where the power input comes from a single nuclear reactor and not from any chemical combustion. During the 1960s an experimental rocket engine with a nuclear fission graphite reactor was built and ground tested with liquid hydrogen as the propellant. It delivered an equivalent altitude specific impulse of 848 sec, a thrust of over 40,000 lbf at a nuclear reactor power level of 4100MW with a hydrogen temperature of 2500 K. No further ground tests of nuclear fission rocketengines have been undertaken 25 NUCLEAR ROCKET ENGINES In a rocket using nuclear thermal propulsion, a working fluid, usually liquid hydrogen, is heated to a high temperature in a nuclear reactor and then expands through a nozzle to create thrust. Providing a higher effective exhaust velocity, such a rocket would double or triple payload capacity compared to chemical propellants that store energy internally. 26 TYPES NUCLEAR ROCKET ENGINES In the nuclear fission reactor rocket, heat can be generated by the fission of uranium in the solid reactor material and subsequently transferred to the working fluid. The nuclear fission rocket is primarily a high-thrust engine (above 40,000 N) with specific impulse values up to 900 sec. 27 TYPES NUCLEAR ROCKET ENGINES In the isotope decay engine a radioactive material gives off radiation, which is readily converted into heat. Isotope decay sources have been used successfully for generating electrical power in space vehicles and some have been flown as a power supply for satellites and deep space probes. 28 TYPES NUCLEAR ROCKET ENGINES Fusion is the third nuclear method of creating nuclear energy that can heat a working fluid. A number of different concepts have been studied. To date none have been tested and many concepts are not yet feasible or practical. Concerns about an accident with the inadvertent spreading of radioactive materials in the earth environment and the high cost of development programs have to-date prevented a renewed experimental development of a large nuclear rocket engine. 29 ELECTRIC ROCKET PROPULSION a class of propulsion which makes use of electrical power to accelerate a propellant by different possible electrical and/or magnetic means. In all electric propulsion the source of the electric power (nuclear, solar radiation receivers, or batteries) is physically separate from the mechanism that produces the thrust 30 ELECTRIC ROCKET PROPULSION Among the three basic types of electric rocket propulsion, electro-thermal rocket propulsion most resembles chemical rocket engines; propellant is heated electrically, either by heated resistors or electric arcs, and the hot gas is then thermodynamically expanded and accelerated to supersonic speeds through an exhaust nozzle. The two other types, namely electrostatic (ion propulsion) engine and the electromagnetic (magneto-plasma) engine, accomplish propulsion by different principles and the thermodynamic expansion of gas in a nozzle, as such, does not apply and both of these types will only work inside a vacuum. 31 SOLAR ENERGY Several technologies exist for harnessing solar energy to provide power for spacecraft and also to propel spacecraft using electrical propulsion. Solar cell, also called photovoltaic cell, any device that directly converts the energy of light into electrical energy through the photovoltaic effect. 32 SOLAR ENERGY Solar thermal rockets, was an attractive concept that were first proposed in 1954 as a way to provide greater specific impulse than chemical rockets. These devices use the sun's energy to heat a propellant(typically hydrogen) to extremely high temperatures and then expel the hot gas through a nozzle to provide thrust. 33