Variation of Cooling Mass Flow Rate and its Effect on Unsteady Aerodynamic and Heat Transfer Performance of a Rotating Turbine Stage

Sperling, Spencer; Celestina, Richard; Christensen, Louis; Mathison, Ronald; Aksoy, Hakan; Liu, Jong

doi:10.2514/6.2020-3698

Cited by 2 publications

(1 citation statement)

References 15 publications

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“…Typically, these sensors have used polyimide as the dielectric material and a platinum deposition on the order of nanometers for the metal deposition [1,2,5,6,10]. These selections allow the sensors to be flexible enough to wrap around complex airfoil geometries with a time response on the order of kilohertz which is critical to characterize harmonics of blade passing events present in turbomachinery flows [10][11][12][13][14][15]. Noteworthy research by a host of institutions over the last several decades has advanced the design and fabrication of these type of sensors [1,[5][6][7]11].…”

Section: Literature Reviewmentioning

confidence: 99%

Application of 3-omega method for thin-film heat flux gauge calibration

Siroka

Foley

Berdanier

et al. 2021

Meas. Sci. Technol.

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Double-sided thin-film resistance temperature detector (RTD) heat flux gauges (HFGs) are commonly used to characterize heat transfer rates in high-heat flux environments with complex flow features. These gauges comprise two thin-film RTDs on opposing sides of a dielectric. To deduce accurate heat flux, the RTDs must be properly calibrated and the material properties of the dielectric must be characterized. This study presents a complete gauge characterization method for sensors of this type by applying standard calibration procedures with specially-designed RTDs capable of utilizing the 3-omega method. The 3-omega method quantifies the thermal conductivity and thermal product of a material by measuring the response of a specially designed heater/thermometer deposited on the substrate. This study shows the 3-omega method enables RTD calibrations and thermal property determination over a range of temperatures for individual gauges, reducing the uncertainty in calculated heat flux. Although the method is quite general, this study utilized platinum RTDs with a polyimide dielectric, which is common in turbomachinery applications. The thermal properties obtained through this method agree with previous characterization efforts; however, discrete characterization of seven gauges shows that gauge-to-gauge variation in the dielectric could influence measured heat flux by as much as 30%. This study also builds the framework to characterize the thermal conductivity of the adhesive layer beneath the gauge which is necessary to mount the sensors to the test article. Although often uncharacterized, the adhesive thermal conductivity has a significant impact on matching experimental measurements to simulations. Additionally, this study found that if the thermal conductivity of the dielectric is constant (an assumption that holds for the present study), an in-situ RTD calibration can be performed. In-situ RTD calibration and traditional method RTD calibration agreed to within 0.1%. Overall, this work has practical implications in obtaining high quality measurements from HFGs of this type.

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