Measurements versus Numerical Simulations for Slotted Synthetic Jet Actuator

Abstract

In many studies concerning synthetic jet flow fields the analysis is usually restricted to simple configurations, such as a single diaphragm oscillating in a cylindrical cavity, which is linked to the external environment with only one orifice/slot. Nonetheless, in many applications the requirement of small sizes and weights leads to many implementation issues, such as asymmetric actuator geometries, presence of several slots and diaphragms and irregular cavity shapes. Therefore, the design of a synthetic jet actuator for a specific flow control problem requires a dedicated study in order to characterize its behavior even in quiescent conditions. The aim of this work is to investigate the behavior of a novel synthetic jet actuator, composed of three independent diaphragms, acting on a single cavity, and linked to the external environment through four slots per diaphragm. The device has been studied in quiescent conditions, both numerically and experimentally. The experimental investigation has been carried out by means of hot-wire measurements. In particular, the distribution of the phase-averaged streamwise velocity along the slot spanwise direction has been detected near the slot exit plane. From the computational side, incompressible direct numerical simulations have been carried out using the open-source OpenFOAM code. The diaphragm motion is mimicked by a inhomogeneous inlet boundary condition, whose amplitude is chosen to match the experimental velocity at the exit plane. A fair agreement between the numerical and the experimental results is achieved for both the velocity field at the slot exit and the main non-dimensional parameters of the synthetic jet. After the validation, the numerical results are finally processed, to obtain information about the vortex motion in the external environment.

Receptivity to synthetic jet actuation in boundary layer flows

“…Further developments led to dedicated lumped-element models (LEM) of complex devices, with more cavities and/or orifices [30,31]. The flow field generated by unconventional SJ actuators, with noncircular orifices or multi-slot and multi-cavity characteristics are still object of current research [32][33][34], and these studies could be the basis for new LEMs. On the contrary, there are no LEMs for the synthetic jets in crossflow, which led the researchers to rely to empirical models or trial-and-error techniques for the design of the actuators.…”

Multiphysics Modeling of a Synthetic Jet Actuator in Operation

“…Modeling the diaphragm as a moving wall with a profile defined by an equation has also been achieved with some success [19]. Some researchers have omitted the cavity and nozzle to simplify computations and focus on the exterior flow [48][49][50]. Some researchers have employed a more realistic multiphysics approach incorporating piezoelectricity and structural mechanics [27][28][29][30].…”

Multiphysics Modeling of a Synthetic Jet Actuator in Operation

“…Modeling the diaphragm as a moving wall with a profile defined by an equation has also been achieved with some success [19]. Some researchers have omitted the cavity and nozzle to simplify computations and focus on the exterior flow [48][49][50]. Some researchers have employed a more realistic multiphysics approach incorporating piezoelectricity and structural mechanics [27][28][29][30].…”