Publications

An unsteady pressure probe for the measurement of flow unsteadiness in tidal channels

An unsteady five-hole probe has been developed for the measurement of turbulent flow in tidal channels. Such measurements are vital for accurate prediction of unsteady loads on tidal turbines. Existing field-based velocimeters are either unable to capture the required range of frequencies or are too expensive to profile the variation of turbulence across a typical tidal power site. This work adapts the traditional five-hole wind tunnel probe to achieve a low-cost device with sufficient frequency range for tidal turbine applications. The main issue in the marine environment is that the ambient hydrostatic pressure is much higher than the dynamic pressure. This has been overcome by using novel calibration coefficients and differential transducers. In flume tank tests against laser Doppler velocimeter measurements, the frequency response of the probe has been shown to be sufficient to capture all the frequencies necessary for tidal turbine design.

Authors:

Young, A., Clark, C., Atkins, N., and Germain, G.

Publication:

IEEE Journal of Oceanic Engineering

DOI:

https://doi.org/10.1109/JOE.2019.2933131

Novel usage of five-hole probes: Tidal channel turbulence measurements

Authors:

Young, A., Guion, R., Atkins, N. and Costan, J.,

Publication:

In proceedings of the XXIII Biannual Symposium on Measurement Techniques in Turbomachinery

Turbine Blade Tip Heat Transfer in Low Speed and High Speed Flows

In this paper, high and low speed tip flows are investigated for a high-pressure turbine blade. Previous experimental data are used to validate a computational fluid dynamics (CFD) code, which is then used to study the tip heat transfer in high and low speed cascades. The results show that at engine representative Mach numbers, the tip flow is predominantly transonic. Thus, compared with the low speed tip flow, the heat transfer is affected by reductions in both the heat-transfer coefficient and the recovery temperature. The high Mach numbers in the tip region (M > 1.5) lead to large local variations in recovery temperature. Significant changes in the heat-transfer coefficient are also observed. These are due to changes in the structure of the tip flow at high speed. At high speeds, the pressure side corner separation bubble reattachment occurs through supersonic acceleration, which halves the length of the bubble when the tip-gap exit Mach number is increased from 0.1 to 1.0. In addit

Authors:

Andrew P. S. Wheeler, Nick R. Atkins, Li He

Publication:

Journal of Turbomachinery

DOI:

10.1115/1.4002424

Download paper