Ablation Experimental Characterization and Numerical Investigation of a 3-Dimensionally Built Carbon/Phenolic Composite for Aerospace Applications

摘要

ArianeGroup has developed a 3-Dimensionally Carbon/Phenolic Composite material (called Naxeco? Phenolic resin material), built from low cost, non-aerospace grade carbon fibers, and a phenolic resin already used to make impregnated 2D ablative fabrics but modified to be compatible with the Resin Transfer Molding (RTM) process. The material is engineered to design low cost ablative freestanding parts, such as nozzle cowl and exit cones or heat shields because of its unique high resistance against delamination. ArianeGroup and Koo Research Group, Austin Texas, conducted an investigation to characterize the ablation behavior of Naxeco? Phenolic resin material. Historically, the method of analyzing the ablation of a material has been primitive: through visual inspection the material before and after exposure. However, the Koo Research Group has developed a sensing technique that enables ablation detection throughout the lifetime of the part, the "In-Situ Ablation Sensor" and a testing method, which enables the collection of optical diagnostics data, the Oxy-acetylene Test Bed (OTB). These tests exposed Naxeco? Phenolic resin material samples to heat fluxes of 350 W/cm~2 and 1000 W/cm~2, which are representing thermal fluxes commonly calculated in nozzle cowl or exit cones and hypersonic vehicle TPS, respectively. This test program generated data from two optical imaging techniques, previously unused by Dr Koo's research group, in addition to the group's proprietary In-Situ Ablation Sensor and a two-color infrared laser pyrometer. In the series of tests under heat flux of 350 W/cm~2, no material surface regression was measured as it is observed on the SRM nozzle parts where this material is used. Under heat flux of 1000 W/cm~2, the material showed behavior in conformity with the ablative performance-versus-density law and it demonstrated again a unique resistance against delamination.