A multiposition hot-wire technique for the study of swirling flows in vortex chambers

A multiposition single-slant hot-wire probe technique for the study of a three-dimensional confined vortex flow is described. Most of the previously reported observations of confined swirling flows were obtained by flow visualization or by using relatively large pressure probes. However, swirling flows are extremely sensitive to disturbances created by such probes. In addition, when such probes are used in turbulent flows, they are subject to errors caused by turbulent fluctuations. Because of these difficulties, more recent measurements have been made with hot-wire anemometers. Hot-wire probes have the advantage of small size, causing minimal disturbance to the flow, coupled with good signal sensitivity and a high frequency response, which enables the study of the occurring turbulence field. General response equations have been developed between Image and v., (the mean and fluctuating effective velocities, respectively). The corresponding derivation of the three main velocity components and six Reynolds stresses has been carried out. Velocity and turbulence intensity measurements have been taken and are presented (using the derived equations) for different exit conditions. These results demonstrate an extreme sensitivity of the flow regime to the exit conditions.