Numerical Simulation Of Synthetic Jets
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Numerical Simulation of Synthetic Jets
Synthetic jet actuators (SJA) or zero-net mass flux (ZNMF) actuators are devices consisting of a cavity with a small orifice or slot, inside of which is a moving oscillator. Thecavity is connected to the external medium by means of a neck. The oscillator drivercan be a diaphragm, whose periodic movement makes the fluid leave and enter the cav-ity. When the flow exits from the neck a train of vortices is formed, to be able to obtainthe jet, these vortices cannot be swallowed back into the cavity when the membrane is moving down. To ensure that this is not happening the parameter jet formation criteria(JFC) is defined. The JFC only depends on geometrical parameters as the longitudeand the amplitude of the membrane, when the movement of the membrane is periodic.When the jet is successfully formed, it is able to transfer kinetic energy and momentumto the fluid without a mass addition. Several potential applications of this technologyexist, e.g, active flow control (AFC), cooling and fuel mixing.The present work solves a SJA impinged into a hot wall. The case at low Reynolds(Re= 50) is considered to be laminar and incompressible. Four different neck longitudes are compared to see which is the importance of the neck length. The strategy to solve these cases is running three meshes with different densities. The simulationwith the less dense mesh can run more cycles spending less computational time, theresults of this mesh are the inputs of the denser mesh. The case is configured usingmoving mesh techniques for the actuator membrane. In this situation, the decouplingof velocity and frequency is no longer possible and other strategies need to be applied.Velocity and temperature are found to reach a steady state after about 50 actuatorcycles, however, the Nusselt number features a low frequency that makes the whole case longer to converge. It is estimated that a number of around 200 actuator cyclesare needed for the Nusselt number to reach the steady state. This fact complicates theflow, despite the fact that the Reynolds number is low. The effect of changing the necklength has a direct effect on the velocity but has little influence on the temperature orthe Nusselt number.
Handbook of Numerical Simulation of In-Flight Icing
Author: Wagdi George Habashi
language: en
Publisher: Springer Nature
Release Date: 2023-12-11
This Handbook of Numerical Simulation of In-Flight Icing covers an array of methodologies and technologies on numerical simulation of in-flight icing and its applications. Comprised of contributions from internationally recognized experts from the Americas, Asia, and the EU, this authoritative, self-contained reference includes best practices and specification data spanning the gamut of simulation tools available internationally that can be used to speed up the certification of aircraft and make them safer to fly into known icing. The collection features nine sections concentrating on aircraft, rotorcraft, jet engines, UAVs; ice protection systems, including hot-air, electrothermal, and others; sensors and probes, CFD in the aid of testing, flight simulators, and certification process acceleration methods. Incorporating perspectives from academia, commercial, government R&D, the book is ideal for a range of engineers and scientists concerned with in-flight icing applications.
Synthetic Jets
Compiles Information from a Multitude of SourcesSynthetic jets have been used in numerous applications, and are part of an emergent field. Accumulating information from hundreds of journal articles and conference papers, Synthetic Jets: Fundamentals and Applications brings together in one book the fundamentals and applications of fluidic actuators.