Patent ID: 9135908
Filing Date: 2015-09-15
Classification: F01N,F16L,G10K,H04R

Abstract:
1. A method of controlling a resonator chamber with variable volume, comprising the steps of: (a) recording a resonant frequency f to be attenuated in non-transitory computer readable memory; (b) randomly selecting a dimensionless area ratio λ in the range of 0.1<λ<1.0, wherein A2 being a cross-sectional area of a neck of a resonator chamber and A1 being a cross-sectional area of a primary chamber of the resonator chamber; (c) establishing a first length parameter L1 associated with a height of the primary chamber having a maximum value L1max given by where c is the speed of sound and L1=L1max−Δ, where Δ is an optimization parameter; (d) establishing a second length parameter L2 associated with a height of the neck of the resonator chamber, wherein where k is the wavenumber given by k=2π/c; (e) maximizing a transmission loss TL of the resonator chamber in terms of the optimization parameter Δ to determine a maximized parameter Δmax which maximizes the transmission loss, wherein (f) calculating the first length parameter L1 as L1=L1max−Δmax; (g) calculating the second length parameter (h) if TL is not maximized for all possible values of λ in the range 0.1<λ<1.0, then returning to step (b), otherwise calculating the height of the primary chamber H1 as H1=L1 and calculating the height of the neck of the resonator chamber H2 as H2=L2−δ1−δ2, where δ2 is a design parameter given by δ2=0.48√{square root over (A2)}(1−1.25√{square root over (λ)}) and δ1 is a design parameter given by and (i) transmitting a control signal to adjust the height of the primary chamber to H1 and the height of the neck of the resonator chamber to H2.