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MEL 715 : GAS DYNAMICS. P M V Subbarao Associate Professor Mechanical Engineering Department I I T Delhi. A Passion of Doing Adventures lead to a Hi-Fi Science and Technology!!!. The Shocking News. People had dreamed of flying for many years. A Shocking News ?#$?%?
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MEL 715 : GAS DYNAMICS P M V Subbarao Associate Professor Mechanical Engineering Department I I T Delhi A Passion of Doing Adventures lead to a Hi-Fi Science and Technology!!!
The Shocking News • People had dreamed of flying for many years. • A Shocking News ?#$?%? • 1 million to 10 million years they might be able to make a plane that would fly ?!?!?! • The United States Army was trying to develop an airplane in 1903, but the plane wouldn't fly. • The New York Times wrote that maybe in1 million to 10 million years they might be able to make a plane that would fly. • Only eight days later two men were successful in flying the first manned plane. • They were Wilbur Wright and his younger brother, Orville.
A Narrow Gap Between Possibility & Impossibility • The would-be aeronauts of the nineteenth century closely studied the flight of birds and began building flying machines patterned after avian structures. • Their birdlike craft failed miserably. • They quickly realized that in reality they knew nothing about the lift and drag forces acting on surfaces cutting through the atmosphere. • To fly, man first had to understand the flow of air over aircraft surfaces. • This meant that he had to build instrumented laboratories in which wings, fuselages, and control surfaces could be tested under controlled conditions. • Thus it is not surprising that the first wind tunnel was built a full 30 years before the Wrights' success at Kitty Hawk. • A science called Aerodynamics leading to Gas dynamics.
Motivating Examples • Re-entry flows • Rocket Nozzle Flows • Jet Engine Inlets • Celestial Gas Flows • Volcanic Gas flows..
Gas Dynamics of Re-entry • A range of phenomena are present in the re-entry of a vehicle into the atmosphere. • This is an example of an external flow. • Bow shock wave : Suddenly raises density, temperature and pressure of shocked air; consider normal shock in ideal air • ro= 1:16 kg/m3 to rs= 6:64 kg/m3(over five times as dense!!) • To = 300 K to Ts= 6100 K (hot as the sun's surface !!) • Po = 1:0 atm !to Ps= 116:5 atm (tremendous force change!!)
Propagation of a Pulsed Protostellar Jet Protostellar jets are unique in that they have high Mach numbers, are overdense compared to their surroundings, and they are strongly radiatively cooled. A large number of studies have reported the dynamical evolution of such jets: cooling results in the formation of thin dense shells which are easily fragmented into clumps and "bullets".