Jet Impingement Tone Suppression Using Powered Resonance Tubes

Abstract

This work is an experimental study of high subsonic jet impingement tone suppression. We begin by documenting the characteristics of the impingement tone for various Mach numbers and standoff (nozzle exit to ground plate) distances. The results revealed frequency staging and the presence of two types of impingement tones. A novel feature of our work is the use of four miniature high-frequency actuators known as powered resonance tubes that were located circumferentially around the main jet nozzle. The powered resonance tubes were capable of producing high amplitude acoustic excitation over a range of frequencies, up to 17.5 kHz. Our target excitation frequency range was about 3-5 times that of the natural flow instability. Using high-frequency excitation, tonal suppression levels as high as 20 dB and broadband suppression levels as high as 5-10 dB were obtained. The mass addition rate from the powered resonance tubes was of the order of 2% of the mass flow rate from the main jet. Mass flow reductions could be obtained under conditions when the powered resonance tube resonated strongly. Our results suggest that appropriately designed miniature powered resonance tube actuators have potential for use in flow control applications. Nomenclature a 1 = speed of sound corresponding to the freestream conditions C 1 , C 2 = correction factors for the main jet velocity and the acoustic velocity, respectively D = main nozzle exit diameter f = frequency of the acoustic wave h = standoff distance between the nozzle exit and ground plate M = Mach number n = number of the impingement stage p = phase shift associated with acoustic wave reflection u = flow velocity = acoustic wavelength Subscripts j = main jet properties PRT = powered resonance tube

Acoustic characteristics of jets impinging on permeable plates

“…Elavarasan et al 29 destroyed the feedback loop by inserting a baffle plate near the nozzle exit in the outside ambient flow region. Kastner and Samimy 30 used Hartmann tube fluidic actuators and steady injection; Sarpotdar et al 31 employed Powered Resonance Tube (PRT) actuators whereas, Alvi and group 27,32 applied microjets to control the noise. Fluidic inserts are applied to reduce the noise produced by jets impinging on aircraft carrier deck.…”

On Flow Field of Radially Emitted Underexpanded Jet

“…In both applications, since the noise produced by the jet deteriorates the working environment, a study on the noise source is important and the measures for noise reduction should be sought. As a simple model of such flow fields, the jet impinging on a flat plate has been studied by many researchers [5][6][7][8]. Among them Powell [6] is well known to propose a feed-back mechanism of the disturbance in the flow field concerning noise generation.…”