The development of a Doppler Global Velocimeter (DGV) for the measurement of transonic turbo-machinery flows in the Oxford Isentropic Light Piston Tunnel rotor facility is described. A novel optical arrangement for capturing both reference and iodine cell discriminated images with a single CCD camera and frame grabber is presented. Practical arrangements for determination of the iodine cell transmission properties as a function of temperature and light frequency are discussed in the context of using an argon ion continuous wave laser for illumination. Flow seeding aspects of the experiment are described with particular emphasis on particle dynamics and light scattering. Error bounds for the DGV measurements are assessed and quantified in respect to the frame grabber resolution and Gaussian beam profile. Results of measurements of the velocity of a rotating disc with tip speed of nominally 90 m/s, obtained with 0.5 W single mode argon ion laser illumination are presented. Practical aspects for employing the DGV on the established Oxford rotor facility, such as seeding of the flow, optical access and synchronisation of data acquisition are addressed.

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