Resonant Interaction of a Rectangular Jet with a Flat-plate

Abstract

A resonant interaction between a large aspect ratio rectangular jet and a flat-plate is addressed in this experimental study. The plate is placed parallel to but away from the direct path of the jet. At high subsonic conditions and for certain relative locations of the plate, the resonance accompanied by an audible tone is encountered. The trends of the tone frequency variation exhibit some similarities to, but also marked differences from, corresponding trends of the well-known edgetone phenomenon. Under the resonant condition flow visualization indicates a periodic flapping motion of the jet column. Phase-averaged Mach number data obtained near the plate's trailing edge illustrate that the jet cross-section goes through large contortions within the period of the tone. Farther downstream a clear 'axis switching' takes place. These results suggest that the assumption of two-dimensionality should be viewed with caution in any analysis of the flow.

Non-homogeneous rapid distortion theory on transversely sheared mean flows

“…(6.55) over the range |y 2 − y d | t d /2 and set (αD) 2 = 2.3 (where D is a characteristic length defined more precisely below) in order to fit the mean flow measurements of Zaman et al (2013). Figure 4, which is in qualitative agreement with experimental observations over the frequency range where amplification occurs, shows that the peak noise levels occur at fairly low Strouhal numbers and increase with increasing Ma.…”

“…As stated earlier, the model problem considered in this section can be used to represent the interaction between a jet emanating from a large-aspect-ratio rectangular nozzle with the trailing edge of a flat plate. Recent experiments on this configuration were performed at the NASA Glenn Research Center Zaman et al 2013). The relevant geometric parameters are shown in figure 5.…”

“…A schematic of the problem is shown in figure 2. This relatively simple geometry can be used to represent the experimental configuration of a subsonic jet emanating from a large-aspect-ratio rectangular nozzle in the vicinity of a flat plate recently considered at the NASA Glenn Research Center Zaman et al 2013). A computeraided design (CAD) drawing of the experimental set-up is shown in figure 3.…”

“…problems involving the interaction of turbulence with solid surfaces and other non-uniformities) by using them to calculate the sound radiation produced by the interaction of a two-dimensional jet with the trailing edge of a flat plate -a problem that is currently of considerable interest because of its relevance to understanding noise production in future aircraft configurations. Comparisons with recent experiments conducted at the NASA Glenn Research Center (Brown 2012;Zaman, Brown & Bridges 2013) are also presented in that section.…”

An Experimental Study on the Characteristics of Rectangular Supersonic Jet on a Flat Plate

“…Seiner and Manning [7] studied supersonic jet-plate flows from a supersonic rectangular nozzle, and they showed that the gap distance between the nozzle exit and plate surface was an important parameter with respect to the jet screech tone. Research has also shown that jet noise characteristics are influenced by the flat plate (flap) length [8][9]. In addition, the turbulence characteristics of such jet flows and their impact on jet noise have also been studied both numerically and experimentally [10].…”