Development of Powered Resonance-Tube Actuators for Aircraft Flow Control Applications

Abstract

The present paper addresses both active-flow-control actuator technology development and the demonstration of the effectiveness of actuators that could be easily integrated into practical aircraft applications. The actuator used is an adaptation of the Hartmann oscillator. Demonstration experiments that illustrate the effectiveness of this actuator include cavity tone suppression at transonic speeds and the reduction of jet-impingement tones. The actuator concept is based on a high-speed jet aimed at the mouth of a cylindrical tube closed at the other end. The result is a high-amplitude self-sustaining fluctuating field accompanied by an intense narrowband tone, all in the region between the supply jet and the resonance tube. Using unsteady pressure sensors and flow visualization, we explored the effect of varying actuator parameters such as the spacing between the power jet and the resonance tube, supply pressure, resonance-tube depth, diameter, shape, and lateral spacing. By varying the depth of the tube, the frequency could be varied from about 1.6 kHz to over 10 kHz and amplitudes as high as 156 dB (microphone location dependent) were obtained in the vicinity of actuation. To integrate this concept into practical aircraft applications, two generations of a more complex version of this device known as the powered resonance-tube bank (PRTB) were developed and demonstrated. Results indicate that by using high-frequency excitation at 5-kHz suppression levels in excess of 20 dB were consistently obtained over a range of operating conditions in both cavity and impingement flow situations. Based on our results, we have grounds to believe that a properly designed PRTB has significant advantages over conventional actuators such as acoustic, piezo, and oscillatory microstructures. Introduction I N this paper we describe the development of novel powered resonance-tube actuators. The actuators operate over a range of frequencies and produce high amplitudes of pressure fluctuations. Such actuators are attractive alternatives to conventional electromagnetic and piezoelectric actuators. The conventional actuators are fragile and have high power and maintenance requirements. This paper describes our attempts to harness the oscillatory field of the Hartmann oscillator by suitable adaptation and integration. The final result is a high-frequency actuator with no moving parts that can inject high-amplitude fluctuations into a flow that we wish to control. Such actuators could eventually replace steady mass-addition methods with oscillatory addition of fluid at lower mass-flow (bleed) levels. Two examples of applications (cavity and impinging jet) that demonstrate the effectiveness of this type of actuator are also provided.The role of an actuator is to inject perturbations at a prescribed frequency, amplitude, and mode (spanwise or azimuthal) at locations where the flow is most receptive to these inputs. The actuation then leverages or disrupts the flow to bring about a desired effect. An example of leveraging is the excitation ...

The Influence of Acoustic Field Induced by HRT on Oscillation Behavior of a Single Droplet

“…However, for the droplets with different initial diameters, the resonance frequency happens at different values and modes, which means that for a specific acoustic frequency, when the resonance frequency of the droplet matches the acoustic frequency, the shape oscillation will reach its maximum. On the other hand, the SPL of the acoustics only affects the specific deformation amplitude, as described in Equations (8) and (21). As with the discussion for cases with different cavity lengths and nozzle pressure ratios in Figure 14.…”

“…Michael et al [20] compared the flow characteristics of a HRT, with and without shielding, with the SA one-equation turbulence model, and they reported that the presence of a shield caused intense flow/shock oscillation around the cavity mouth. Raman et al [21] concluded that properly designed HRT had significant advantages over conventional actuators, such as acoustic, piezo, and oscillatory microstructures, and could be widely used in an active-flow-control field.…”

Application of Hartmann Acoustic Generator in Source of Underwater Pyrotechnic Combustion

“…Hartmann acoustic generator mainly consists of nozzle and circular resonant cavity which is characterized by simple construction, low cost and producing high intensity sound in liquid [6,7]. The Hartmann acoustic generator is one such device which can be effectively used in numerous applications such as coagulating and precipitating dust and smoke using sound waves, atomization, active noise control and ignition device of rocket engine in aviation field [8][9][10][11][12][13].…”

Jet Impingement Tone Suppression Using Powered Resonance Tubes

“…However, it is surprising that the potential of this incredibly simple device has not been fully exploited. Murugappan and Gutmark [17], Kastner et al [18], Raman and Kibens [19], and Raman et al [20] have investigated the application of PRTs for controlling high speed flows. The use of the PRT and other active flow control actuators is also described in a review paper by Raman and Cain [21].…”