Numerical Solution of Lateral Jet and Nozzle Effects on Aerodynamic Coefficients of a Re-entry Hypersonic Projectile

One of the most common methods for controlling and increasing maneuverability of projectiles, especially the ones which move at high altitude and in low density air, is using lateral or reaction jets. The resultant force of the reaction jet is related to the jet and flow parameters. For finding their relation experimental, numerical, and analytical methods have been used. In order to change the pendulous path of a hypersonic projectile, when is returning to the atmosphere (free flight), we compared common lateral jet method with the common ones, using a lateral nozzle (or a blunt body). For this purpose, a projectile with known geometry and minimum angular acceleration for 20 degrees circulation is assumed. Hence, we can decide about parameters of a suitable reaction jet and lateral nozzle for changing the path of a hypersonic projectile. Aerodynamic forces and moments from jet and lateral nozzle (or a bluntbody), which are the result of angular acceleration of the projectile with jet and lateral nozzle, are obtained by producing a three-dimentional mesh on a model projectile and solving the Navier-Stocks equations (assuming ideal gas and an appropriate flow regime with respect to height). Results show that in order to change the pendulous path of a hypersonic projectile, more than one nozzle reaction jet should be used and also a combination of a reaction jet and a bluff body (like a sphere) can be used.