No abstract

The dual bell nozzle concept's primary goal is to increase performance through the idea of selfadaptation for two operating regimes without mechanical activation. The dual bell nozzle type known asthe planar double divergent nozzle (DDN) has a rectangular cross section. In this study we propose anumerical method for the design of the nozzle profile with double planar divergent. The design of the doubledivergent nozzle is carried out in two parts. The first divergent is a contour of a two-dimensional supersonicnozzle with a sharp-edged throat that gives uniform parallel flow at the exit. The method of characteristicapplied to the two-dimensional isentropic flow of an ideal gas was used for the design of a supersonic planarnozzle. The contour of the second divergent (nozzle extension) is a polynomial. This is achieved using thedirect method of characteristics. A numerical analysis of a double divergent nozzle, and a planar nozzlewith the same area ratio and the same length using ANSYS-Fluent software. The analysis's findingsindicated that the double divergent nozzle had a weight decrease of 0.61%. The thrust increase is estimatedat 3.88% in the low-altitude operating mode for the double divergent nozzle.

The focus of this research work is to investigate numerically the effect of adding the gas on the design and performance of axisymmetric MLN nozzles. A FORTRAN code was developed to design this nozzle using the characteristics method (MOC) at high temperature. The thermochemical and combustion studies of the most used liquid propellants on the satellites and launch vehicles allow to known all gases. Four engines are investigated: Ariane 5 (Vulcain 2), Ariane-5 upper stage engine (Aestus), Zenit first stage (RD-170) and Falcon 9 upper stage (Raptor). Thermodynamic analysis of parameters design MLN (such as length, Mach number, mass, thrust coefficient) was conducted. The comparison shows that the presence of 50% of H2O gas in combustion species increases the nozzle design parameters (diatomic gas including air) in the order of 25%. On the other hand, the existence of CO2 gas considerably increases approximately 35% the length and the exhaust radius. These rise depend on gases percentage in the combustion. The truncation method is applied in the MLN nozzles to optimize the thrust/weight ratio.