Predicting the gas-wall boundary conditions in a thermal barrier coated low temperature combustion engine using sub-coating temperature measurements

Abstract

Low temperature combustion (LTC) engines exhibit potential to significantly reduce fuel consumption and nitric oxide emissions over traditional spark ignited (SI) engines. A prior study has shown that thermal barrier coatings (TBCs) can increase the temperature swing during combustion, thus bolstering both low load LTC operation and its combustion efficiency. However, no attempt has been made so far to maximise the benefits through optimisation of TBC thermal and morphological properties. In this work, a finite element model was developed to expeditiously determine crank-angle resolved TBC surface temperatures across a spectrum of potential TBC thermal and morphological properties and facilitate exploration over a large design space. The simulation was validated using crank-angle resolved temperature and heat flux data from TBC coated, fast-response thermocouples. Experiments were carried out using a metal piston, and a TBC coated piston. Subsequent numerical study characterises the sensitivity of the temperature swing on the surface to TBC conductivity.