%0 Journal Article %A Acharya, Ragini %D 2008 %I Begell House %N 5 %P 399-419 %R 10.1615/IntJEnergeticMaterialsChemProp.v7.i5.40 %T GRAPHITE ROCKET NOZZLE EROSION RATE REDUCTION BY BOUNDARY-LAYER CONTROL USING ABLATIVE MATERIALS AT HIGH PRESSURES %U https://www.dl.begellhouse.com/journals/17bbb47e377ce023,6b0442161c2f317b,613a59a26dc13ed7.html %V 7 %X The objective of this work is to study the effect of a nozzle boundary-layer control system (NBLCS) for reducing the nozzle throat erosion rates at broad range of pressures from 7 to 48 MPa (1,000 to 7,000 psia). A comprehensive model for graphite nozzle erosion minimization (GNEM) and numerical code developed by the authors, have been advanced to include the effect of gas-mixture injection from a NBLCS, which contains four center-perforated grains of ablative materials (made of succinic acid and poly-vinyl acetate) positioned across the nozzle entrance. This design allows a small portion of hot combustion product gases generated from the rocket-motor combustor to enter into the center-perforated ablative grains, which causes the evaporation of the ablative material to produce relatively low-temperature fuel-rich gases to be injected in an upstream location of the nozzle throat station. The injection of this gas-mixture is numerically shown to reduce the bulk temperature of combustion product gases into the boundary-layer region near the throat thereby resulting in a much cooler nozzle throat surface. This injection also reduces the mass fractions of the oxidizing gaseous species such as H2O, OH, and CO2 in the combustion products, thus reducing the chemical attack on the nozzle throat surface. The erosion rates of the graphite nozzles at ultra high-pressure operating conditions are significantly reduced by several orders of magnitudes and the thermochemical erosion process becomes a kinetic-controlled process. %8 2008-10-01