Skip to main content
. Author manuscript; available in PMC: 2020 Apr 21.
Published in final edited form as: Appl Acoust. 2014 Jul 24;87:153–161. doi: 10.1016/j.apacoust.2014.07.008

Table 1.

Main parameters.

Variable Description Non-dimensional
Do Orifice diameter _
Dt Tube diameter DT/Do
to Orifice plate thickness to/Do
L1 Upstream length L1/Do
L2 Downstream length L2/Do
La Absorption thickness La/Do
Um Mean flow velocity Orifice Mach number (Mo = Um/c*)
fex Excitation frequency Orifice Strouhal number (fex Do)/Uex
Aex Excitation amplitude (pressure) SPL = 20 Log (P/P0**)
*

c denotes speed of sound at the laboratory temperature c = (γRT)0.5.

**

P0 denotes the reference pressure: P0 = 2 × 10−5 Pa.