VENTED NOZZLE CONCEPT FOR OPTIMUM PERFORMANCE OF LAUNCH VEHICLES

THE VENTED NOZZLE IS AN INNOVATIVE CONCEPT TO AERODYNAMICALLY MODULATE THE NOZZLE FLOW AREA DURING FLIGHT OF A LAUNCH VEHICLE AND THUS GREATLY IMPROVE THE NOZZLE PERFORMANCE. IT REQUIRES A LARGE AREA RATIO NOZZLE WHOSE WALLS ARE VENTED THROUGH A SERIES OF SPRINGLOADED CHECK VALVES. THIS ALLOWS CONTINUOUS AND PASSIVE ADJUSTMENT OF EXHAUST TO AMBIENT PRESSURES AND ALSO REDUCES THE TRANSIENT START LOADS ON THE NOZZLE. IN PHASE I OF THIS PROJECT, AN EXISTING CFD CODE WILL BE USED TO EXAMINE THE FEASIBILITY OFTHE BASIC CONCEPT. A SPACECRAFT NOZZLE, SUCH AS THE SSME NOZZLE, WILL BE ANALYZED WITH SEVERAL VENT CONFIGURATIONS. BASIC PERFORMANCE PARAMETERS AND FLOW DISTRIBUTIONS WILL BE STUDIED FOR SEVERAL PRESSURE RATIOS TO SIMULATE OPERATION ATVARIOUS ALTITUDES. EFFECTS OF FLOW PROTRUSIONS, INTRODUCED UPSTREAM OF CHECK VALVES TO ENHANCE THE RELIABILITY OF THEIR OPERATION, WILL ALSO BE ANALYZED. IN PHASE II, OPERATIONAL QUESTIONS SUCH AS SIDE LOADS DUE TO FAILED VALVES WILL BE ANALYZED AND AN OPTIMUM NOZZLE DESIGN WILL BEDEVELOPED AND TESTED. THE ADAPTED CFD CODE WILL ALSO SERVE AS A VALUABLE DESIGN TOOL.