OCTOBER 19-20, 2012 - YMCA University of Science & Technology

Proceedings of the National Conference on
Trends and Advances in Mechanical Engineering,
YMCA University of Science & Technology, Faridabad, Haryana, Oct 19-20, 2012
Thrust per unit mass flow rate = V 2 – V 1 = (9.966+002) – (3.32e+002) = 6.644e+002 N Kg -1 s = 664.4 N Kg -1 s
Fig 3.10: Pressure distribution in the proposed model (sectional view)
Fig 3.11: Pressure distribution in the proposed model (side view)
Pressure difference between the front and rear faces would result into form or pressure drag which is detrimental
to the model.
Approximate pressure difference =2.094e+004-(-2.419e+005) Pa =2.513e+005 Pa
4. Conclusion
Just by bringing about certain changes in the design of the body and channelling the ambient air to pass through
the body in a certain way it was possible to create an additional thrust to the body without affecting the fuel
consumption. After the converging passage was introduced the pressure difference was utilized to make the air
exit the converging passage at high velocity, which being coherent in nature also helped to straighten out the
eddies that were being formed in the wake region. In rockets channelling ambient air from the front and sides
will also increase the mass flow rate of the exhaust gases: If these designs of converging passages are
introduced into the body of a rocket such that the passage would channel the ambient air into the exhaust of the
rocket, from where all the exhaust gasses of rocket propulsion exit the rocket, not only it would create an
additional thrust for the rocket (because of the increased kinetic energy) but it would also increase the mass flow
rate of the exhaust gasses which would in turn further increase the thrust for the rocket according to impulse
momentum theorem. The analysis has been performed on a general aerodynamic body, its practical
implementation is still a difficult task because of the complex design problems related to the real bodies.
Moreover, if a method is devised to vary the outlet cross-section with the help of PID controllers, thrust
generation can be optimized for different speeds. It has been established by the above result that circular and
rectangular section provides a higher maximum out velocity, however an elliptical cross-section provides a
more coherent flow field. Structurally, a circular section is easy to carve out and most symmetrical thus must be
preferred. The structure can have any cross-section suiting to the particular application.
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