Efforts to reduce the noise from turbulent jets at fixed flow conditions, with aircraft noise as the principal technological motivation, have generally involved some degree of parametric empiricism often based upon a series of trial-and-error testing. As a result, it is unclear if the modest reductions found, in rare cases that do not greatly affect the flow field or incur prohibitive losses, a...

This paper reports on the simulation of the near-nozzle region of a moderate Reynolds number cold jet flow exhausting from a chevron nozzle. The chevron nozzle considered in this study is the SMC001 nozzle experimentally studied by the researchers at the NASA Glenn Research Center. This nozzle design contains six symmetric chevrons that have a five-degree penetration angle. The flow inside the ...

We have succeeded in measuring a substantial portion of the two-point space-time velocity correlation in hot, highspeed turbulent jets. This measurement, crucial in aeroacoustic theory and the prediction of jet noise, has been sought for a long time, but has not been made due to the limitations of anemometry. Particle Image Velocimetry has reached a stage of maturity where sufficient measuremen...

Astable regimes are common in nonlinear systems ranging from electrooptic devices to cardiac rhythms under environmental stress. Electrosprays exhibit three main axial regimes (dripping, pulsating, and cone-jet). It is generally accepted that the transition between the pulsating and cone-jet regimes is sudden, accompanied by an abruptly enhanced spray current. Here we present an alternative to ...

In the present paper the characterization of the flow field generated by means of a submerged gaseous jet exited by means of a coaxial synthetic jet has been investigated. The purpose of this investigation is to infer the aerodynamic interaction of the two fluid structures that play an interesting role in several industrial applications like jet actuator, flame stability in the combustor for mi...

Taguchi Method is explained in brief and one of the textile processes, called spinning process, is optimised by using Taguchi method for manufacturing optimum packing density of different technologies yarns. The effect of process variables like: lap hank, card draft, draft/doublings and drafts at speed frame, ring frame, rotor and air-jet spinning machine on packing density parameters of respec...

In an Orthogonal Frequency Division Multiplexing (OFDM) systems, the Peak to Average power Ratio (PAR) is high. The clipping signal scheme is a useful and simple method to reduce the PAR. However, it introduces additional noise that degrades the systems performance. We propose an oversampling scheme to deal with the received signal in order to reduce the clipping noise by using finite impulse r...

Experimental investigations on the noise characteristics in spool valve with v-notches are conducted in this paper. Cavitation noise with frequency peak forms when the flow state changes form single phase turbulent to cavitating. The peak frequency decreases with the increase of the flowrate. On the other hand, jet flow develops intensely from the notches. Self-sustained flow oscillation produc...

Image data compression by fractal techniques has been widely investigated. Although its high compression ratio and resolution-independent decoding properties are attractive, the encoding process is computationally demanding in order to achieve an optimal compression. A variety of speed-up algorithms have been proposed since Jacquin published a novel fractal coding algorithm. Unfortunately, the ...

Recent research efforts on nonlinear propagation from high performance jet aircraft have revealed an interesting challenge to predicting community response. This challenge focuses on receiver perception of these unique acoustical signals, which contain acoustical shocks that appear to increase their relative loudness and/or noisiness. This current finding suggests a need for an improved descrip...