title: Comments on the low frequency radiation impedance of a duct exhausting a hot gas.
abstract: The influence of convection and temperature on the radiation impedance of an open duct termination exhausting a hot gas is commonly described by a complex theory. A simplified analytical expression is proposed for low frequencies. Both models assume a free jet with uniform velocity bounded by infinitely thin shear layers. The convective velocity that should be assumed when applying these models to a non-uniform outflow is uncertain. A simplified version of the so-called Vortex Sound Theory demonstrates that the convective velocity one should assume is lower than the jet centerline velocity.
authors.affiliation: Department of Applied Physics, Technische Universiteit Eindhoven, Postbus 513, 5600 MB Eindhoven, Netherlands A.Hirschberg@tue.nl.
authors.forename: Avraham
authors.initials: A
authors.lastname: Hirschberg
authors.affiliation: Department of Mechanical Engineering, Technische Universiteit Eindhoven, Postbus 513, 5600 MB Eindhoven, Netherlands P.M.G.Hoeijmakers@tue.nl.
authors.forename: Maarten
authors.initials: M
authors.lastname: Hoeijmakers