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Analysis of Rocket Propulsion

THE TSIOLKOVSKY ROCKET EQUATION. Force Balance on A Rocket. Let. For a typical launch vehicle headed to an orbit, aerodynamic drag losses are typically quite small, on the order of 100 to 500 m/sec. Gravitational losses are larger, generally ranging from 700 to 1200 m/sec depending on the shape of the trajectory to orbit. By far the largest term is the equation for the space velocity increment..

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Analysis of Rocket Propulsion

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    1. Analysis of Rocket Propulsion P M V Subbarao Professor Mechanical Engineering Department

    2. THE TSIOLKOVSKY ROCKET EQUATION

    3. Force Balance on A Rocket

    6. REACHING ORBIT The lowest altitude where a stable orbit can be maintained, is at an altitude of 185 km. This requires an Orbital velocity approximately 7777 m/sec. To reach this velocity from a Space Center, a rocket requires an ideal velocity increment of 9050 m/sec. The velocity due to the rotation of the Earth is approximately 427 m/sec, assuming gravitational plus drag losses of 1700 m/sec. A Hydrogen-Oxygen system with an effective average exhaust velocity (from sealevel to vacuum) of 4000 m/sec would require Mi/ Mf = 9.7.

    7. Geostationary orbit A circular geosynchronous orbit in the plane of the Earth's equator has a radius of approximately 42,164km (26,199 mi) from the center of the Earth. A satellite in such an orbit is at an altitude of approximately 35,786km (22,236 mi) above mean sea level. It maintains the same position relative to the Earth's surface. If one could see a satellite in geostationary orbit, it would appear to hover at the same point in the sky. Orbital velocity is 11,066 km/hr= 3.07 km/sec (6,876 miles/hr).

    8. Travel Cycle of Modern Spacecrafts

    9. MULTISTAGE ROCKETS With current technology and fuels, a single stage rocket to orbit is still not possible. It is necessary to reach orbit using a multistage system where a certain fraction of the vehicle mass is dropped off after use thus allowing the non-payload mass carried to orbit to be as small as possible. The final velocity of an n stage launch system is the sum of the velocity gains from each stage.

    10. ANALYSIS OF MULTISTAGE ROCKETS

    16. MOMENTUM BALANCE FOR A ROCKET

    17. EFFECTIVE EXHAUST VELOCITY

    19. 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.

    20. Criteria of Performance

    21. Thrust (F)

    22. Specific Impulse (I or Isp)

    23. Total Impulse (Itot)

    25. Effective Exhaust Velocity (c)

    26. Thrust Coefficient (CF)

    27. Characteristic Velocity (c*)

    28. Thermodynamic Performance - Thrust

    29. Thermodynamic Performance - Specific Impulse

    30. Thermodynamic Performance - Specific Impulse

    31. 31 Thrust Coefficient (CF)

    32. Thrust Coefficient (CF) - Observations

    33. Actual Rocket Performance

    34. Internal Ballistics Liquid propellant engines store fuel and oxidiser separately - then introduced into combustion chamber. Solid propellant motors use propellant mixture containing all material required for combustion. Majority of modern GW use solid propellant rocket motors, mainly due to simplicity and storage advantages. Internal ballistics is study of combustion process of solid propellant.

    35. Solid Propellant Combustion Combustion chamber is high pressure tank containing propellant charge at whose surface burning occurs. No arrangement made for its control charge ignited and left to itself so must self-regulate to avoid explosion. Certain measure of control provided by charge and combustion chamber design and with inhibitor coatings.

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