Aerotherm Chemical Equilibrium (Ace) and Charring Material Thermal Response and Ablation Programs (Cma) Tutorial

Discipline: Thermal Control & Protection

The main thermal design considerations in a solid rocket motor (SRM) nozzle are erosion and char of the insulation liner and the bondline temperature between the liner and overwrap. The bondline between the liner and overwrap usually has a temperature limit it must not exceed by end of burn (EOB). The ACE/CMA code calculates the thermal erosion and char of the carbon phenolic in the nozzle exit cone at each station and the heat conduction into the aft exit cone which provides bondline temperatures used for requirement validation. The ACE/CMA model results can be validated by data obtained from a static motor test. With the validated model, bondline temperature predictions can be made using 3σ erosion and char.

This presentation will illustrate the various steps involved in creating this analysis. Included will be a description of the various codes, inputs required and how the various outputs from codes are used as inputs for other codes to arrive at a solution. The process used to match data and validate the model will be discussed. The results will demonstrate what looked like an issue, the bondline exceeding the required temperature, is not because the predicted bondline temperature transient shows the exceedance occurs significantly after EOB.

About the Presenter:
Mr. O’Malley received his B.S. in Chemical engineering from Arizona State University in 1979 and his M.S. in Mechanical engineering from University of Iowa in 1985. He was employed by Thiokol Corporation at Promontory, Utah for 13 years in the thermal group specializing in SRM motor joint flow/thermal analysis and nozzle ablation analysis. Significant experience was gained while involved in the redesigned solid rocket motor effort after the Challenger accident. Presently employed by NASA, supporting the LSP program for the last 20 years. LSP specializes in integration of spacecraft to launch vehicles, qualification of spacecraft components and entire launch vehicles, thermal analysis, anomaly resolution and launch console support. Supported from its inception, the qualification effort for the GEM63 and GEM63XL SRM program for the Atlas V and Vulcan programs.

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