Tikani, R., Vahdati, N., Ziaei Rad, S., Esfahanian, M., “A New Approach for Double-Notch Frequency Hydraulic Mounts", Inter-Noise 2010, Portugal.

Abstract: Passive hydraulic mounts are broadly applied in the aerospace applications to isolate the
cabin from the engine noise and vibration. In these applications definitely on turbofan
engines, the notch frequency of each hydraulic mount is adjusted to either engine low speed
shaft imbalance excitation frequency (N1) or to engine high speed shaft imbalance excitation
frequency (N2) at the cruise condition. Since most of today's passive hydraulic mount
designs have only one notch, isolation is only possible at N1 or at N2, but not at both. In this
paper, a novel double-notch passive hydraulic mount design is displayed, which has two
notch frequencies, and therefore can provide vibration and noise isolation at two different
frequencies. Also in this new design one can use two working fluids, one being a controllable
fluid. The new passive hydraulic mount design concept and its mathematical model are
presented in details and some discussions on the simulation results are also included.