ABSTRACT
The purpose of the nozzle in a rocket engine is to expand the high-pressure hot gases generated by burning the propellant to a higher jet velocity for producing the requisite thrust. In order to enhance the thrust, the exhaust gas in the nozzle can be expanded fully to ambient pressure with parallel and uniform exit flow. The area ratios of the nozzle need to be changed continuously to adapt the nozzle performance with altitude. In order to overcome the problem of actuation mechanism of the extendible nozzle, a dual nozzle has been designed and developed by combining the two segments of the nozzle with a hump between them. When ambient pressure changes with altitude, hot gases fill the larger portion of the diverging section of the nozzle. It may be noted that the velocity at the nozzle exit under isentropic expansion condition is higher than that in the non-isentropic condition due to increased entropy caused by friction, and turbulence effects.
