Design of Funnel Port Tubular Propellant Grain for Neutral Burning Profile in Rockets

Radial outward burning tubular propellant grain gives progressive burning profile, but trimming port at one end to conical form gives close to neutral burning profile. Though this configuration is easy to realize, but close-form burnback equation for performance prediction of such propellant geometry is not available. In this paper, close-form burnback equation for conically trimmed tubular propellant grain is developed. One propellant grain is also evaluated and performance matching to prediction by developed formulation is realised. Parametric study for different aspect ratio (L/D), diameter ratio (d/D) and slant angle (θ) is carried out for a typical configuration and variation is explained. The developed formulation is simple, handy, easy and quick.