An Analytical Study on the Influence of Rocket Nozzle Geometry on Thrust Generation

The nozzle is a tube-shaped device that is used for releasing hot exhaust gases coming from the combustion chamber. The gases are accelerated, often to supersonic velocities, thus providing the thrust needed to overcome the gravitational pull on the rocket. In other words, the process of propulsion is governed by Newton’s Third Law, since downwards momentum of exhaust gases leads to the upwards momentum of the rocket. The shape of the nozzle is a critical parameter which should be considered when designing this element of the propulsion system because it impacts greatly on the overall rocket’s effectiveness. Over time, the forms of nozzles have become more complicated from conical to types such as bell, plug, expansion-deflection, double bell and multi-nozzle grids. However, among all these options, conical and bell nozzles still receive considerable attention from scientists and engineers and, thus, serve as a good basis for further nozzle research. The losses of energy that occur during the process of propulsion result in the reduction of the velocity of exhaust gases leaving the nozzle and, consequently, the thrust produced. That is why choosing the apt nozzle geometry is crucial during the design process and maximising propulsion performance. This study presents a comparative analysis of conical and bell nozzles based on existing literature, with emphasis on their influence on thrust generation. It critically examines how nozzle contour affects momentum transfer, divergence losses, and overall propulsion efficiency, providing a comprehensive evaluation of these performance characteristics.