Borescope for Infrared Thermography of Turbine Guide Vanes During Operation

Abstract This paper introduces the development and commissioning of an infrared thermography-based borescope for spatially resolved surface temperature measurement of the turbine’s first stage guide vane row of Kawasaki’s L30A gas turbine (30 MWel class). It has been developed in a cooperation between B&B-AGEMA GmbH and Kawasaki Heavy Industries, Ltd. (KHI). Main parts of the borescope are a heat-resistant pressure casing with internal cooling, an IR endoscope with remote focus adjustment, and an IR camera. The optical axis runs radially from the outer casing towards the center of the shaft. The projected image contains the rear part of the pressure side of a guide vane, the inner shroud platform of the flow channel, and a part of the suction side of the neighboring guide vane. The new borescope has been successfully commissioned in 2024. We confirmed the integrity of the borescope for all operating points up to the rated power of the gas turbine. The measured spatial temperature distribution enables the validation of the cooling system of the inner shroud platform. We find a good agreement between the temperature distributions in a qualitative comparison with the color distribution of thermopaint. The analysis of an advanced film cooling hole at the inner shroud platform showed that the cooling efficiency and the effective direction of the cooling film are independent of the gas turbine load.