The requirements to reduce engine fuel burn costs and gaseous emissions combine to ensure that gas turbine engine manufacturers continually seek to increase the peak cycle temperatures of new engine designs. Consequently, high-pressure turbine components must be developed that can withstand increasing gas temperatures, resulting in the continuous introduction of new technologies that allow appropriate service life. Accurate gas path measurements are vital for early understanding of the performance of a new design, although the accurate measurement of fluid temperature in a turbine stage is becoming increasingly difficult. The use of active probe-assembly cooling is important to ensure a sufficiently robust measurement system. Cooling issues may also affect the measurement performance because the component to which the temperature instrumentation is attached is cooled (for example, a guide vane). The use of a radial traverse total temperature device in the turbine section of a large civil aero-engine has previously been reported and the results analysed and compared to expectation. One outcome of ongoing work has been a proposal for a new design of turbine traverse probe with improved total temperature measurement accuracy. The new design directly addresses those uncertainties caused by conduction of heat from the thermocouple junction and into the cooled probe support. Extensive conjugate CFD modelling followed by validation tests in a high temperature free-jet rig confirmed the success of the design in reducing the magnitude of the thermal conduction error. The probe is likely to be used in future tests to improve engine performance validation.

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