烧蚀反应动力学参数的确定

DETERMINATION OF KINETIC DATA OF ABLATIVE REACTIONS

关键词:  喷管烧蚀计算  固体火箭发动机  复合材料  反应动力化学  参数估计

Key words:  Ablation  Nozzle throat  Solid rocket engine  Composite  Reaction kinetic chemistry  Parameter estimation

摘要:

本文提出了一种理论模型与实验相结合确定碳基材料烧蚀反应动力学参数（活化能和指前因子）的方法。首先建立了碳基材料热化学烧蚀的湍流边界层模型,运用数值方法对边界层守恒方程组、表面烧蚀和固相热传导进行耦合求解,计算过程中不需要事先假设烧蚀的控制类型。其次,在电弧加热器中模拟火箭发动机喷喉的烧蚀环境进行烧蚀材料与氧化性气体反应的烧蚀实验。最后,运用所建立的模型和在电弧加热器上的实验结果进行预测比较,确定烧蚀反应的动力学参数。作为实例,确定了石墨与CO₂的烧蚀反应的动力学参数。

Abstract:

A method combining theoretical model with test results to determine kineticparameters (activation energy and pre-exponential factor) of ablative reactions forcarbon-base materials has been developed.The theoretical model is based on ananalysis of a turbulent boundary layer over a carbon surface with thermo-chemical ablation.The boundary layer equations coupled with surface ablation equations and heat conduction equations are solved simultaneously and numerically and the ablative type needn’t be pre-assumed in the calculation process.Ablation of material with oxido-gas has been tested in an arc-plasma jet which simulates the flow conditions at rocket nozzle throat.Compared computional results from the proposed model with experimental data,the chemical kinetic properties of the ablative reaction are obtained. The chemical kinetic properties of graphite reacting with CO2,as a practical example,was determined in the paper.