Tech@Edu

ELECTRICAL ROCKET ENGINES Electric propulsion engines generate exhaust velocities from about 4 to more than 100 times those of chemical rocket engines. There are three basic types of electrical rocket engines. They are : 1. Arc plasma rocket engine 2. Ion rocket engine 3. Magneto-plasma rocket engine 1. ARC PLASMA ROCKET ENGINE It is one of the simplest types of electrical rocket engines. It consists of: (1) Propellant tank (2) Combustion chamber (or) thrust chamber (3) Cooling system (4) Electric power supply The combustion chamber (or) thrust chamber contains two electrodes. The nozzle walls serve as the cathode, and an electrode within the chamber is serve as the anode. Liquid fuel from the propellant tank is pumped to a thrust chamber. When electric power supply is given, an arc is formed between cathode and anode. When the propellant is passing through the arc, an electrically neutral plasma gases (ionized gases) are produced. The highly heated plasma gases are then allowed to ex

NUCLEAR ROCKET ENGINE In nuclear rocket, nuclear energy is used to heat the propellant or working fluid to get high temperature in the combustion chamber. Liquid hydrogen is widely used as a propellant. The combustion chamber consists of nuclear fission reactor, reflector, moderator, control rods, etc. Parts of Nuclear Rocket Engine 1. Nuclear Reactor It is an apparatus in which heat is produced due nuclear fission chain reaction. Nuclear reactors are used at nuclear power plants for electricity generation, propulsion of ships and also in nuclear thermal Rocket Propulsion system. Components of Nuclear reactor 1. Reflector - Reflects neutrons produced in the reaction back into the core. It's Prevents neutron leakage & maintains reaction balance. 2. Shielding - Shielding is required to protect the working men from the harmful effects of the radiation. 3. Moderator - To slow down neutrons from high velocities and hence high energy level which they have on being released from fis

HYBRID PROPELLANT ROCKET ENGINE The hybrid rocket engines combine the advantages of both solid and liquid propellant rockets. In this type, solid fuel along with liquid oxidizer is used as a propellant. Solid fuel is packed in the combustion chamber and the liquid oxidizer is stored in the separate tank. Working The liquid oxidizer which is stored in the separate tank is injected into the combustion chamber. When liquid oxidizer mixes with solid fuel in the combustion chamber, combustion takes place automatically. When the combustion takes place in the combustion chamber, very high pressure and very high temperature gases are produced. The highly heated products of combustion gases are then allowed to expand in the nozzle section. In the nozzle, pressure energy of the gas is converted into kinetic energy. So the gases coming out from the unit with very high velocity. Due to high velocity of gases coming out from the unit, a force (or) thrust is produced in the opposite direction. This

SOLID PROPELLANT ROCKET ENGINE A solid propellant rocker engine Solid propellant is the combination of solid fuel (plastic or resin material) and oxidizer (nitrates, perchlorates, etc.) Solid fuel and oxidizer are homogeneously mixed and packed inside the shell. A liner is provided between the shell and the propellant. The purpose of liner is to protect the shell because high temperature will be generated during combustion process.  Working  In solid propellant rocker engine   the igniter located at the top and ignites the spark. So combustion takes place. When the combustion takes place in the combustion chamber, very high pressure and very high temperature gases are produced The highly heated products of combustion gases are then allowed to expand in the nozzle section. In the nozzle pressure energy of the gas is converted into kinetic energy. So the gases coming out from the unit with very high velocity. Due to high velocity of gases coming out from the unit, a force (or) thrust is

 LIQUID PROPELLANT FEED SYSTEM There are two types of liquid feed system. They are : (1) Gas pressure feed system (2) Pump feed system 1. GAS PRESSURE FEED SYSTEM In the gas pressure feed system an inert gas (Helium or Nitrogen) is stored in a tank at high pressure and it is passed into pressure-regulator valves. This high pressure inert gas from the regulator is used to force the propellants (Fuel and Oxidizer). The propellants under high pressure are forced to flow into the combustion chamber through control valves. Several regulating and check valves are used for filling, draining and checking the flow of propellants. Moving parts such as pumps and turbines are not used. Therefore, this system is considerably simpler. The pressurization of the propellant tank is comparatively much heavier. So, this system is not suitable for large rocket engines and long range missions. 2. TURBO PUMP FEED SYSTEM In this system, liquid fuel and the liquid oxidizer are stored in a separate tank at low

 LIQUID PROPELLANT ROCKET ENGINE In the Liquid propellant rocket engine liquid fuel (refined petrol, liquid hydrogen, hydra-zine, etc.) and liquid oxygen are used in this engine.Liquid fuel and liquid oxygen are stored separately in two different tanks. Preheater is used to heat the fuel and oxidizer. Nozzle is used to increase the velocity and decrease the pressure of the gases. Working * Liquid fuel and liquid oxygen are pumped separately into a combustion chamber through control valves. * Since the liquid fuel and liquid oxygen are stored at very low temperature, they are preheated in the preheater to a suitable temperature. * The preheated fuel-oxidizer mixture is injected into the combustion chamber through suitable injector and combustion takes place. * When the combustion takes place in the combustion chamber, very high pressure and very high temperature gases are produced. * The highly heated products of combustion gases are then allowed to expand in the nozzle section. * In th

 ROCKET PROPULSION The thrust required for the propulsion of rocket is produced by the high velocity of gases leaving  from the nozzle which is similar to Jet propulsion.  In Jet Propulsion, the oxygen required for combustion is taken  from the atmosphere. But in the case of rocket propulsion, since the  altitude of rocket engine is very high, enough oxygen is not available  in the atmosphere. So the oxygen is filled in a tank in the rocket  engine itself and used for combustion purposes. CLASSIFICATION OF ROCKET ENGINES Rocket engines are classified as follows: Method of Propulsion 1. Chemical rocket engines 2. Nuclear rocket engines 3. Electrical rocket engines 4. Solar rocket engines Chemical rocket engines can be classified as: 1. Liquid propellant rocket engine 2. Solid propellant rocket engine 3. Hybrid propellant rocket engine Nuclear rocket engines can be classified as: 1. Fusion rocket engine 2. Fission rocket engine Solar rocket engines can be classified as: 1. Solar sail roc

WELDING AS COMPARED TO CASTING  &  RIVETING 1. Welding is more economical & fast process as compared to riveting & casting. 2. Fabricated mild steel structure are lighter as compared to cast. 3. Welding can join dissimilar metals & thus in a complicated structures & different parts of the structure can be fabricated with different materials as compare to riveting & casting. 4. It’s a noiseless process as compare to riveting & Casting. 5. Cost of pattern making & storing is eliminated. 6. As compared to casting & riveting fewer persons are involved in welding. 7. A welding structure processes a better finish as compared to riveting & casting.  8. Layout of punching or drilling of holes is not required in welding.  9. Welding fabrication involve less inventory as compared to casting since no pattern are involved.  10. Structural shapes are not easily obtained by casting & riveting, can be produced by welding without much difficulty.  11.

Welding Welding is a process of joining similar and dissimilar metals or other material by application of heat with or without application of pressure and addition of filler material. ” Or “Welding is a fabrication process that joins materials, usually metals or thermoplastics, by using high heat to melt the parts together and allowing them to cool, causing fusion .” Welding is distinct from lower temperature  metal-joining  techniques such as brazing and  soldering, which do not melt the base metal.  It is used as permanent fasteners. Welding is  essential process of every manufacturing  industries such as computer industries,  mechanical industries, petroleum industries,  chemical industries etc.