Study of fluid-dynamic behavior in a convergent–divergent nozzle by shape optimization using evolutionary strategies algorithms

Abstract

The performance and thrust of a rocket propulsion system are based mainly on the utilization of the enthalpy of the propellants in the combustion chamber. This accumulated energy is transformed into kinetic energy by the expansion and acceleration of the gases produced by the chemical reaction of combustion, using a device known as a nozzle. This project studies the aerodynamic profile to trace the wall contour of a C-D nozzle based on the technical operating conditions of a rocket engine. The wall contour is traced using different design methods and, for each nozzle section, the behavior of the fluid-thermal properties of the flow field along the flow trajectory of the aerospace nozzle is analyzed. This is necessary because, in each wall contour suggested by the models, the angle of inclination of the curvature is different (the concavity or shape of the curve changes) and, therefore, the physical magnitudes of the properties vary according to the contour. To determine which design complies with the concept that processes occurring within a nozzle are isentropic and reversible, a statistical analysis of data dispersion is performed to choose the design with the lowest energy losses as a function of friction and entropy. An unconstrained optimization is applied to maximize or minimize the cross-sectional area of the nozzle geometric profile through genetic algorithms. To corroborate the nozzle wall contour and the design methodology used, a simulation is performed to evaluate the similarities between the operating characteristics and Mach number with another nozzle of a J-2 rocket engine.