NUMERICAL MODELING OF FULLY VISCOUS ROCKET PLUME FLOWS

THE PLUME PRODUCED BY THE GAS FLOW THROUGH THE NOZZLE OF A ROCKET ENGINE OR SYSTEM VENT ON A SPACECRAFT CAN CONTAMINATETHE SPACECRAFT, ITS SENSORS AND OTHER NEARBY APPARATUS. ANALYTIC METHODS FAIL FOR DENSE OR COOL EXHAUST GAS, WHICH EXHIBITS VISCOUS BOUNDARY LAYER FLOW, AND NUMERIC SOLUTIONS FOR THE NOZZLE CORE FLOW ARE THEN PATCHED TO THOSE FOR THE BOUNDARY LAYER FLOW. THE RESULTING CONTINUUM SOLUTION IS THEN PATCHED TO A MONTE CARLO SOLUTION FOR THE FREE-MOLECULAR REGIME. THE RESULTING SOLUTION ONLY MODELS STEADY PLUMES, SO THAT THE START-UP AND SHUT-DOWN PROBLEM ISNOT INVESTIGATED. FOR THIS PHASE I EFFORT THE 2-D FULLY VISCOUS UNSTEADY PLUME PROBLEM IS SOLVED IN THE CONTINUUM REGIME. THE PROPOSED NUMERICAL METHOD IS WELL-ADAPTED TO SOLVING TIME-DEPENDENT FLOWS INCLUDING VISCOSITY, STEEP GRADIENTS AND EVEN SHOCKS, AND IS THEREFORE CAPABLE OF CALCULATING THE FULLY TIME-DEPENDENT FLOW OF A ROCKET NOZZLE DURING A COMPLETE PULSE. IN PHASE I, THE NUMERICAL METHOD WILL BE APPLIED TO A CONICAL NOZZLE, AND FULLY VISCOUS CALCULATIONS OF THE PLUME OF A PULSED THRUSTER WILL BE PERFORMED, USING N2 OR HELIUM PROPELLANT. THE NEAR-FIELDFLOW PREDICTED BY THESE CALCULATIONS WILL BE BENCHMARKED AGAINST CALCULATIONS AND EXPERIMENTS FROM THE LITERATURE FOR STEADY-STATE PLUMES.