Compact fluid-borne noise silencers for aviation hydraulic systems

The aviation environment holds challenging application constraints for efficient hydraulic system noise reduction devices. Besides obligatory strong limits on component weight and size, the high safety and reliability standards demand simple and maintenance-free silencer solutions. Hence, basic Helmholtz-Resonators and inline expansion chambers are state-of-the-art aboard commercial aircrafts in service. Unfortunately, they do not meet today's noise attenuation performance aims regarding passenger comfort and equipment durability. Furthermore, production and installation costs have to be considered, plus particular aircraft operating conditions. Commercial aircrafts come with relatively high operating pressures of 210/350bar (3000/5000psi) and fluid-borne noise fundamental frequencies up to approximately 1200 Hz for some of the hydraulic pumps. This conference contribution discusses a new compact approach for an inline expansion chamber, named Disc- Silencer that accounts for the mentioned aviation constraints. The silencer chamber is designed as smooth expansion in only one radial direction relative to the connected piping. The perpendicular radial dimension is kept identical to the piping diameter. This results in a flat rectangular cross area of the flow passageway instead of a circular shape, enabling new options for installation and further incremental development. In this paper, the modelling and experimental validation of such an unconventional hydraulic silencer are presented.

Schlagworte

Aircraft hydraulic system

Attenuator

Expansion chamber

Flow impedance modeling (FIM)

Fluid-borne noise

Hydraulic system noise

Silencer

Silencer test methods

Transmission loss rating

Options

Compact fluid-borne noise silencers for aviation hydraulic systems