Abstract
In this study, surface temperature maps of three turbocharger turbine wheels subject to three different tests, were generated using Thermal History Coatings (THCs). THCs are ceramic-based sensor coatings doped with a luminescent ingredient and the coating luminescence permanently changes with temperature. Therefore THCs can be used to assess temperatures post-test (i.e. offline). A parallel study was performed to optimize the THC application to the turbine wheels because of their complex geometry by deliberately altering the THC application parameters between the three wheels. An initial comparison of the THC data to Conjugate Heat Transfer (CHT) simulations of each test was also made.
The THC-derived temperature profiles measured reflected the test conditions each wheel was subject to. The wheel temperatures were generally hottest at the blade leading edges and decreased radially towards their hubs. The surface resolution of the temperature maps was 1–2 mm and there was good coverage across the wheel surfaces. Some THC erosion occurred at the leading edge of the wheel exposed to the most extreme environment, but the coating was not optimized for this particular test. The coating applied to one turbine wheel showed the most success, with excellent durability along the blade leading and precise blade-to-blade measurements. The initial CHT/THC comparison for this turbine wheel was very promising, with the vast majority of points showing a temperature difference < 10 °C at like-for-like surface locations for the case of one wheel.
Concluding, THC technology was successfully used to profile temperatures of turbocharger turbine wheels. Future work aims to apply thermal history coating technology to further turbocharger development (e.g. E-Turbo applications) and on other inaccessible turbocharger components (e.g. bearing cartridges).
