Submitted by Dhirendra singh

Roll no-1271940903 ME-3rd year

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1-Rocket principle2-rocket propellant3- type of rocket propellant ● solid propellant rocket ● liquid propellant rocket ●gas propellant rocket ● hybrid propellent rocket3- Rocket fuel selection

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Rocket Principles

High pressure/temperature/velocity exhaust gases provided through combustion and expansion through nozzle of suitable fuel and oxidiser mixture.

A rocket carries both the fuel and oxidiser onboard the vehicle whereas an air-breather engine takes in its oxygen supply from the atmosphere.

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How Rocket Engines OperateRocket propulsion is based

on Sir Isaac Newton’s three laws of motion. The third law is the heart of rocketry because the action of the rocket engine produces the forward motion of the rocket.

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Types of Rocket EnginesSolid Propellant

• In a solid propellant rocket system the fuel and oxidizer are mixed together from the start.

• The rocket case is the combustion chamber and holds the propellants. There are no valves, pumps, or sensors. Additives, if needed to increase temperature or to control burning, are simply mixed with propellant grains.

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SOLID ROCKETS AND NOZZLE FLOW

Special issue with solid propellants that use powdered metals as a fuel additive

Adding aluminum to formation of solid propellant increases gas temperature, but incurs performance penalties related to solid particles that are generated Aluminum burns with oxygen to form Al2O3 particles

Particles are initially liquid and solidify during expansion processAlso tend to agglomerate to become large particlesLarge particles do not accelerate as quickly as the gas surrounding themThese particles may constitute as much as 10-25% of total massNeed to consider this in nozzle design, which must account for two-

phase flow

Simplified models exist for analysis of performance: Results indicate that large particle sizes are a detriment However, for small particles, there is an optimum amount of Al to add

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Liquid propellant rocket

Liquid Propellant Classifications• Monopropellants

Contains its oxidizer and fuel in one solution. May be a single chemical compound. The compounds are stable at ordinary

temperatures and pressures, but break down when heated and pressurized, or when the breaking down process is started by a catalyst.

Monopropellant rockets are simple since they need only one propellant tank and associated equipment.

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Types of hybrid Rocket EnginesHybrid Propellant

• Hybrid propellants combine in a single rocket engine many of the advantages of both liquid and solid propellant rockets.

• Flexibility gives the hybrid rocket its biggest operational advantage. It can be throttled from zero to full thrust and can be stopped and started in flight.

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Solid Fuel, Liquid Oxidizer Example

ROCKET FUEL SELECTION GUIDEDesirable Physical Properties

Low freezing point High specific gravity (dense propellant) Stability (with time) Heat transfer properties Pumping properties (low vapor pressure, low viscosity) Small variation in physical characteristics with temperature Ignition, combustion, and flame properties

Performance of PropellantsEconomic FactorsPhysical Hazards (Explosion, Fire, Spills)Health HazzardsCorrosion

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