Numerical Investigation of Dynamic Characteristics of a Fluidic Device

Abstract

Fluidic devices are of interest with turbomachinery internal air systems for modulation of cooling air and other applications. Generally, the flow states within a fluidic device are switched by control flow or flows. For most fluidic devices the switching procedure is almost instantaneous and hence it is difficult to characterize the performance of a device experimentally. The objective of this research is to numerically investigate the dynamic characteristics of a control flow operated fluidic device. In this study the dynamic characteristics of a nozzle during switching is considered. The simulations considered the unsteady interaction of the control flow with the nozzle jet for two different switching scenarios namely, switching of high to low flow state and vice versa. The magnitude of static pressure applied at the control port was identified as a controlling parameter and had to be below a critical value to achieve stable switching. The CFD solutions show that this is related to the flow physics and critical momentum flux ratios for switching are calculated for the present device.