Posts Tagged with Tuned Acoustic Absorber

Active Boom Noise Abatement in a Sport Utility Vehicle (SUV)

Large vehicles, such as sport utility vehicles (SUVs) and minivans, exhibit body boom phenomena during multiple source excitation events including rough road/impact and power-train induced events. The main cause of the boom is the low-frequency acoustic/vibroacoustic standing waves (modes) of the cabin cavity being excited via the high acoustic transfer functions at multiple paths, due […]

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Active Boom Noise Abatement in a Sport Utility Vehicle (SUV)

  An active boom noise control solution which can be viewed as a low-frequency ‘active tuned acoustic damper’ is developed to add acoustic damping to the low-frequency standing waves inside the cabin of a large SUV to quiet its tonal persistent boom noise.  The existing stock 8 inch subwoofer as well as one of the […]

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Active Boom Noise Damping in Rooms/Cabins

Problem: Most rooms/cabins have dimensions that favor standing waves (resonant modes) which are in the range of vibration frequencies of the propulsion engines, gensets, or other machinery on board watercraft. undesirable and unfortunate coupling of the room acoustic modes with the machinery vibration frequencies results in boom/rumble in the room. such low-frequency noise, which is […]

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Self-Tuning of Tuned Dampers/Absorbers

The use of a tuned damper or a dynamic absorber in time-varying systems can only be effective if they are adjustable (semi-active) and continuously returned to the current resonant frequency of the system. Such dampers require a tuning algorithm that can automatically adjust the adjustable parameter of the tuned damper/absorber, e.g., the stiffness of the […]

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Flame Instability (Combustion-driven Oscillation) Mitigation

The performance of modern combustion systems including fuel efficiency, emissions, pattern factor, and lean flammability limit depend on the mixing process between the combustion air and the fuel. For proper mixing, modern combustors rely on a combination of large and small scale turbulent eddies and vortices to control mixing, fuel droplet dispersion (for liquid fuel), […]

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Perforated Liner Tuned Acoustic Absorbers

In many noise control applications, the offending noise occurs only in a narrow range of frequencies or even at a single frequency. Noise generated by industrial machines/equipment mostly falls in this category. For such situations, it is possible to design a sound absorption system that is “tuned” to those target frequencies. One of the most […]

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Effectiveness of Adjacent Reactive Absorbers

In some sound absorption applications, it is necessary to use more than one reactive absorbers (such as quarter-wave tubes or Helmholtz resonators) all tuned to the same frequency. Close placement of these resonators can have an adverse impact on their effectiveness. When such devices are placed along the direction of variation in the shape of […]

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Active Feedback-Controlled Boom Noise Damping/Absorption in a Large SUV

Large vehicles, such as SUVs (Sport Utility Vehicle) and minivans, exhibit body boom phenomena during multiple source excitation events including rough road/impact and powertrain induced events. The main cause of the boom is the low-frequency acoustic/vibro-acoustic modes of the cavity being excited via the high acoustic transfer functions at multiple paths, due to an inherently […]

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