Prediction of erosion in cementitious materials subject to high thermal and pressure loading

Abstract

The project is a collaboration between the University of Central Lancashire and British Aerospace Warton concerned with the modelling of onset of failure in limestone concrete, due to hot jet exhaust gases impinging on the concrete surface.
The temperature distribution was produced using a constant jet temperature with a standard finite difference approximation and the thermal properties of concrete which varied with respect to temperature. The properties of concrete were measured with an initial free moisture content of either 0% or 100%. The finite difference approximation of the saturated concrete simulation was further developed to model the evaporation of free pore moisture. The model predicted surface temperatures were then compared with experimental surface temperatures produced as a result of jet impingement. The results showed good correlation between modelled and experimental results especially at the higher temperatures.
Although the various models produced very similar surface temperatures, the distribution of temperature in the plane
perpendicular to the surface showed significant variation. The temperature distributions were expressed in terms of thermal
stress using firstly an elastic constant to failure and secondly an elastic-plastic model based on the stress-strain curve of concrete. The results produced by the respective models were then compared with experimental data of time to onset failure. The results showed that an elastic model was predicting failure sooner than was seen in practice. The elastic-plastic model was however predicting onset of failure times that were compared with experimental data. The saturated temperature distributions applied to the elastic-plastic model increased the period sustained beneath the jet and the evaporation of free pore moisture was not a significant factor in the prediction of failure.