Heat transfer during transient compression: measurements and simulations

Experiments have been performed to assess the utility of unsteady one-dimensional heat conduction modelling for the calculation of heat losses during a free piston compression process. Heat transfer measurements have been obtained within a gun tunnel barrel using surface junction thermocouple instrumentation. The gun tunnel was operated with a relatively heavy piston such that the shock waves induced by the piston motion were weak. Peak heat transfer values are estimated reasonably well by the unsteady one-dimensional model. However, overall quantitative agreement between the measurements and calculations has not been achieved at this stage, principally because the development of turbulent heat transport was not properly modelled. keywords: heat transfer measurements, heat transfer modelling, free piston compression