Phase-angle measurements between hot-wire signals in the turbulent wake of a two-dimensional bluff body

Measurements have been made of the phase difference between the signals of two hot wires separated in the stream direction and placed in and close to the turbulent wake of a two-dimensional bluff body. Results are presented in the form of the wavelength and the phase speed of perturbations at the vortex shedding frequency for various positions in the flow. It is shown that values of the phase speed may be obtained that are in agreement with published values of the vortex transport velocity. It is necessary to ensure that the hot wires are close to the paths of the centres of the vortices in the wake, otherwise spurious results caused by the influence of the bound vorticity at the model will be obtained.