Hybrid synthetic jets as the nonzero-net-mass-flux synthetic jets

Abstract

The “hybrid synthetic jet” combines the zero-net-mass-flux synthetic jet and fluidic pumping through a valveless pump. No fluid is supplied from an external source (blower or compressor). Hot-wire experiments on a demonstration model confirm that the hybrid synthetic jet exhibits a higher extrusion volume flow rate than the ordinary synthetic jet. For the tested configuration, the increase is by 25% at the 1.30 ratio of the extrusion and suction volume fluxes.

Flow control in axial fan inlet guide vanes by synthetic jets

“…Following the previous experience with SJ actuators (Trávníček et al [8][9][10][11][12]), the full scale axial fan was equipped by electrodynamically driven SJ actuators, located at the IGVs. Namely three SJ actuators were built in the fan casing near the IGVs at the expected separation points.…”

“…where u 0 (t) is the instantaneous orifice velocity on the axis and T E is the duration of the extrusion stroke, which can be considered T E = T/2 under the present harmonic actuation [2,10].…”

“…The time-mean orifice velocity U 0 , relevant to the extrusion stroke is defined by integrating the velocity cycle [2,10,11]:…”

A new method for fluid input into a hybrid synthetic jet actuator

“…Since the end of the last century, the topic has been intensively investigated [1][2][3] and many useful applications of synthetic jets have been developed. Hybrid synthetic jets (HSJs, or non-zeronet-mass-flux jets), which were first introduced in [4][5][6], are very similar to SJs; they are generated by means of non-zero-net-mass flow in the nozzle. The applications of both, SJs and HSJs, may be found especially in boundarylayer separation control [7][8][9], jet vectoring [10], and heat transfer enhancement [11,12,6,13,14].…”

“…The outgoing fluid is responsible for formation of the coherent vortical structures in the immediate vicinity of the nozzle exit. The large vortex structures and higher jet velocities increasing the Reynolds number lead to an augmentation a e-mail: kordik@it.cas.cz of convective heat transfer of the jet [13,6,25] and removal of the already heated (or cooled) fluid from the neighborhood of the heat transfer surface. This is the reason why the HSJAs producing non-zero-net-mass-flux have a great potential in heat transfer applications, even greater than common SJs (this was confirmed experimentally in [13]).…”