A visualized study of flow pattern and pressure distribution in a fluidic device

An attempt to define the flow pattern and pressure distribution in a wall attachment amplifier is reported. The pressure distribution was visualized using air as a working fluid and photographing with a Mach-Zehnder interferometer, using a supply pressure of 20,000 Pa. The flow pattern visualization was accomplished using the hydrogen bubble, tuft, surface floating, and suspension methods. The stream lines and the equivorticity lines were predicted numerically from the vorticity transport equation and the definition of vorticity in the case of Re at 2000, and a divergence from prediction was noted for the pressure distribution. The Coanda effect was observed to strengthen as the control flow rate increased, and separation of an attached vortex shifted to the upstream side at higher Re and the downstream side at a higher control flow rate.