FEASIBILITY DEMONSTRATION OF A TRANSPIRATION COOLED NOZZLE SYSTEM

The use of transpiration cooling for advanced solid propellant application is described. The mechanism used for demonstration purposes consisted of a porous tungsten insert cooled by anhydrous ammonia supplied from an externally pressurized source. Discussion of analytical derivations include heat transfer, stress, design application, and porous tungsten material processing. Size range of the units tested were 2.4 to 2.7 inches throat diameter. Evaluation of methods of creating a pressure tight seal between the insert and coolant chamber are discussed. These methods included welding, brazing, and mechanical seals. It was determined that the best joint was created by a mechanical shrink-fit seal. Materials used for construction of the test units included CGW and RVD graphite, tantalum, and silica and graphite cloth reinforced phenolics. The selection and general performance of these materials is reviewed.