Team

Dr Christopher Clark

Senior Research Associate

Biography

Chris studied as an undergraduate at University of Cambridge, undertaking a Masters thesis on turbine secondary flows. A PhD followed on utilizing splitter vanes in axial turbines to mitigate secondary flows in low aspect ratio vanes.

Chris is currently a research fellow in turbine aerodynamics, working with Rolls-Royce on their future civil propulsion. He is also a Bye-Fellow of Queens' College.

Research topics

Chris currently focuses on improving the aerodynamic performance of turbines. Targeting the losses associated with secondary flows as well as film cooling, he combines experimental testing campaigns with state of the art simulations.

From his experimental experience he has undertaken work into pneumatic probe design. Working on pneumatic probe designs, and calibrations, that avoid errors associated with non-uniform flow fields.

Chris is also interested in how data based techniques can be applied to the aerospace industry. In particular effective methods to use data in the design process are currently lacking. With the increase in compute power making large datasets of simulations more frequent these methods look set to play a significant part in the future of aerodynamic design.

Publications & updates

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

A Pneumatic Probe for Measuring Spatial Derivatives of Stagnation Pressure

This paper introduces a pneumatic 9-hole probe which can measure flow angles, stagnation and static pressures, and spatial derivatives of stagnation pressure. It does this through direct measurement at a single location, rather than empirical corrections using measurements at multiple points. The new design resembles a 5-hole probe with 4 additional holes positioned around the side of the probe head. This arrangement enables the probe to distinguish between flows with stagnation pressure gradient and flows at an angle. Mapping between the inputs, the probe hole pressures, and outputs, the calibration reference measurements, is achieved with a trained neural network which takes the place of a conventional calibration map.

Authors:

C.J. Clark, S.D. Grimshaw

Publication:

Proceedings of ASME Turbo Expo 2019

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