Rocket Nozzle Performance Optimization Using Modified Turbulence

Abstract

Vortex generators are widely used for enhancing the nozzle thrust output by creating different effects. The Ranque-Hilsh effect is observed in a swirling nozzle flow within a single tube is a spontaneous separation of total temperature. Here the colder stream near the tube centre line and the hotter air near its periphery. Hence the temperature difference due to the presence of disturbed flow can either increase (or) decrease the thrust output. This analysis is made of the velocity, temperature and pressure distribution in a turbulent vortex with radial and axial flow. The controlled flow expansion by modifying the geometry in the downstream of throat region can yield better shock expansion characteristics. The most important factor affecting the total temperature of a fluid element in a compressible vortex is the turbulent shear work done on or by the element. The parameter which is considered for this optimization of the vortex generator is exit nozzle opening area, Efficiency of Energy Separation, Profile of velocity, temperature, Length of the tube. Further the experimental investigation of output mass flow rate by geometry modification also will be studied. Computational Fluid Dynamics (CFD) based optimization procedure using the Parabolized Navier-Strokes (PNS) equation is used to design axisymmetric nozzle. The advantage of this procedure is that it accounts for viscosity during the design process. Remaining process will make an approximated Boundary Layer Correction after the inviscid design is created. The nozzle design begins with concerning control volume and the separation of Aerodynamic and Propulsive forces and moments will be demonstrated. The appropriate control volume can define the propulsive force vector that maximizes cruise efficiency. The different boundary layer thickness must be evaluated at various temperature and pressure conditions. Then the influence of boundary layer thickness in the net output will be evaluated numerically. The nozzle configuration of a truncated perfect nozzle is selected for computations. The starting process of unsteady flow characteristics and flow separation are observed carefully. The reattachment of the flow through nozzle is also visualized using the computational analysis.