Patent ID: 8439158
Filing Date: 2013-05-14
Classification: F01N,G10K

Abstract:
1. An acoustic resonator, comprising: a pipe defining a resonant chamber having a longitudinal axis, the pipe having an open end and a closed end; a resonating fluid located in the resonant chamber; a resistance member extending from the open end of the resonant chamber inwardly toward, but not extending to, the closed end of the resonant chamber, the resistance member having first and second end surfaces, the first end surface being located at the open end of the resonant chamber, the second end surface being located at the antinode of a standing wave occurring in the resonant chamber, the resistance member including a high resistance region and a radially inward low resistance region located adjacent one another as viewed along a plane extending perpendicular to the longitudinal axis and extending through the resistance member, the high and low resistance regions presenting different resistances to motion of the resonating fluid, whereby the primary resonance frequency of the resonator is lower than it would be absent the presence of the resistance member.