Discharge device

A discharge device comprising a conduit having an outlet end having an end surface and having a porous permeable body having a central longitudinal axis, and having a core having pores and a side surface, wherein said core is connected to an annular layer having pores wherein said annular layer is arranged around the side surface of the core, and wherein the permeability of the annular layer is smaller than the permeability of the core and wherein the porous permeable body is fustro-conically shaped, tapering in the direction of fluid flow during normal operation and wherein the ratio of the thickness of the annular layer to the diameter of the largest end surface is between 0.01 and 0.10 and wherein the pores of the core have a diameter between 0.10 and 1.0 mm and wherein the pores of the annular layer have a diameter between 0.05 to 0.10 times the diameter of the pores of the core and wherein the core comprises a metal foam having interconnected cells and the annular layer comprises wire gauze and the porous permeable body is joined to the outlet end of the conduit so that the central longitudinal axis of the porous permeable body extends in the direction of fluid flow through the outlet end during normal operation, wherein resistance to flow through the porous permeable body in the direction of its central longitudinal axis is larger than resistance to flow through the porous permeable body in a lateral direction.