SUMMARY

Excess noise is an on-going problem in fluid power systems. The high speed of sound of hydraulic fluid and the low fundamental frequencies of pumps result in wavelengths of sound that are much longer than the size of noise control components. Thus, it is difficult to construct compact devices for reducing fluid-borne noise in fluid power systems. It is proposed that a solid, compliant lining, manufactured of syntactic foam, can lower the speed of sound in the fluid, which may, among other effects, result in lower resonant frequencies and thus smaller noise control devices. A syntactic foam liner is introduced to a prototype Helmholtz resonator, tuning cable, and Herschel-Quincke tube to reduce the size of the components relative to their unlined and non-syntactic foam-lined counterparts. The transmission loss of the devices will be measured from 0-2000 Hz using three different syntactic foam liners, along with their non-syntactic foam counterparts, at temperatures between 20 and 45C and static pressures from 2.1-20.7 MPa. Material properties are available from the liner manufacturer only at ambient pressure, therefore, analytical models will be developed using the wave-decomposition method that will capture the relevant physics. These models will then be used to estimate the properties of the materials at elevated hydrostatic pressures. Knowledge of the behavior of the materials at elevated pressures, and the development of the analytical models, may then be coupled to develop predictive models of the devices for tailored applications.