2. 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!!!

3. 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 in 1 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.

4. 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.

5. Motivating Examples Re-entry flows Rocket Nozzle Flows Jet Engine Inlets Celestial Gas Flows Volcanic Gas flows..

6. Descent of A Spacecraft

7. Landing of A Space Craft

8. Applicability of Continuum Theory

9. Entry Interface Gas Dynamics

10. Re-Entry

11. 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  o = 1:16 kg/m 3 to  s = 6:64 kg/m 3 (over five times as dense!!) To = 300 K to T s = 6100 K (hot as the sun's surface !!) Po = 1:0 atm !to P s = 116:5 atm (tremendous force change!!)

12. Rockets : An Example of Internal Flow

13. Rocket Nozzle Flows

14. Jet Engines

15. Supersonic Jet Engines

16. Supersonic Jet Engine Inlets

17. Volcanic Gas Dynamics

18. 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".