Active Acoustic Control of a Rocket Fairing Using Spatially Weighted Transducer Arrays

Lane, Steven A.; Kemp, Jonathan D.; Griffin, Steven; Clark, Robert L.

doi:10.2514/2.3662

Cited by 12 publications

(8 citation statements)

References 7 publications

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“…Lane et al used an H 2 dynamic feedback controller based on a time-domain system identification of the structural-acoustic system. Their approach was later successfully demonstrated on a fiberglass payload fairing test article [19].…”

Section: A Controlmentioning

confidence: 97%

Active Vibroacoustic Device for Noise Reduction in Launch Vehicles

Griffin

Lane

Lazzaro

2008

Journal of Spacecraft and Rockets

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This paper presents the development of a noise mitigation device for launch vehicle fairings and the performance of the device as measured from sounding rocket experiments conducted by the U.S. Air Force Research Laboratory, Space Vehicles Directorate. A new modeling approach to predict the internal acoustic response particular to sounding rockets is presented wherein the interior noise results from the time varying accelerations acting through the forward bulkhead. This model is different from typical approaches used for payload fairing noise prediction in which the primary noise sources are the rocket motors. This model would also apply to rockets of a similar aspect ratio and acceleration profile. The active acoustic absorber presented in this work can be tuned for optimal performance just minutes before launch. Acceleration and acoustic measurements from two sounding rocket launches are presented to validate the modeling approach and to demonstrate the performance of the active acoustic absorber. Data showed that a single device achieved an 8.8 dB reduction in the sound pressure level from 20 to 300 Hz. Nomenclature Bl= loudspeaker force constant, N=A c = loudspeaker viscous damping constant, N s=m ft = loudspeaker applied force, N K f = filter gain k = loudspeaker stiffness, N=m L = loudspeaker inductance, H m = loudspeaker mass, kg P ref = reference pressure, Pa P rms = pressure rms, Pa R dc = resistance, v a t = loudspeaker voltage, V = frequency shift ratio = loudspeaker damping ratio f = low pass filter damping ratio p = spring/mass/damper damping ratio = bandpass filter damping ratio ! f = low pass filter resonance, rad=s ! p = spring/mass/damper resonance, rad=s ! = bandpass filter resonance, rad=s

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Section: A Controlmentioning

confidence: 97%

Active Vibroacoustic Device for Noise Reduction in Launch Vehicles

Griffin

Lane

Lazzaro

2008

Journal of Spacecraft and Rockets

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“…A convergence study on the spatial sampling was performed by computing NRS using 1,2,4,8,16, and 20 sets of measurement points across the surfaces of the shell. The NRS was mostly converged by 8 points, and the difference between 16 and 20 points was indistinguishable.…”

Section: Measurement Of Sound Transmissionmentioning

confidence: 99%

Investigation of the Sound Transmission into an Advanced Grid-Stiffened Structure

Vipperman

Avdeev

et al. 2003

Journal of Vibration and Acoustics

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The noise transmission behavior of an advanced grid-stiffened (AGS) composite structure has been investigated by combining numerical and experimental methods. Structuralacoustic coupling was found to be light, permitting separate analysis of the structure and acoustic cavity. Finite element analysis permitted the resonant frequencies of acoustic cavity and structure to be calculated, which play an important role for noise transmission through the structure. Acoustic mode shapes permitted internal coincidence frequencies to be estimated and provided insight into modal pressure distributions, when considering payload location. Experimental structural and acoustic modal analysis permitted the resonant frequencies and damping ratios for the structure and cavity to be determined, which in turn were used to corroborate the FEA model. Finally, direct measurement of the noise transmission was performed based on noise reduction spectrum (NRS), which is calculated from spatial averages of the RMS acoustic pressures inside and outside of the shell. It was found that the NRS was dominated by acoustic resonances, which were marked by sharp dips in the NRS curve. Internal coincidence of the axial wavenumbers was also found to be a significant mechanism for noise transmission. External coincidence and ring frequencies were found to provide less of an impact on the overall NRS for the structure.

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“…Work investigating active control technologies applied to launch vehicle payload fairings focuses on the use of smartmaterial based structural actuators 1 and acoustic actuators 2 . However, both of these investigations employed centralized control system designs.…”

Section: Introductionmentioning

confidence: 99%

Decentralized Vibration Control in a Launch Vehicle Payload Fairing

Frampton

2002

Noise Control and Acoustics

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The vibro-acoustic environment inside a launch vehicle payload fairing is extremely violent resulting in excessive development costs for satellites and other payloads. The development of smart structures and active noise and vibration control technologies promised to revolutionize the design, construction and, most importantly, the acoustic environment within these fairings. However, the early promise of these technologies has not been realized in such large-scale systems primarily because of the excessive complexity, cost and weight associated with centralized control systems. Now, recent developments in MEMS sensors and actuators, along with networked embedded processor technology, have opened new research avenues in decentralized controls based on networked embedded systems. This work describes the development and comparison of decentralized control systems that utilize this new control paradigm. The controllers are hosted on numerous nodes, possessing limited computational capability, sensors and actuators. Each of these nodes is also capable of communicating with other nodes via a wired or wireless network. The constraints associated with networked embedded systems control that the control systems be relatively simple computationally, scalable and robust to failures. Simulations were conducted that demonstrate the ability of such a control architecture to attenuate specific structural modes.

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Active Acoustic Control of a Rocket Fairing Using Spatially Weighted Transducer Arrays

Cited by 12 publications

References 7 publications

Active Vibroacoustic Device for Noise Reduction in Launch Vehicles

Active Vibroacoustic Device for Noise Reduction in Launch Vehicles

Investigation of the Sound Transmission into an Advanced Grid-Stiffened Structure

Decentralized Vibration Control in a Launch Vehicle Payload Fairing

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