Porous Baffles Research Articles

The Use of Porous Baffles to Control Acoustic Vibrations in Crossflow Tubular Heat Exchangers

This paper describes how a single porous baffle can be used to prevent the occurrence of acoustic vibration in a crossflow tubular heat exchanger. A method for determining the optimum location and the optimum specific flow resistance of the porous baffle is presented. Finally, a description of how a porous baffle was successfully applied to control acoustic vibration which was occurring in the heat recovery region of a 375-MW brown coal steam generator is given.

Measurements of Entrainment by a Free Rotating Disc

Summary:Measurements are presented of the amount of air which flows axially towards the surface of a disc rotating at various speeds when the nature of flow is turbulent.The method used is similar to that of Ricou and Spalding for the case of the axisymmetrical turbulent jet. The area to one side of the disc is surrounded by a chamber, leaving a small gap between the chamber and the disc. Air is injected into this via a porous baffle until the pressure in the chamber is uniform and atmospheric, a condition which is taken to signify that the “entrainment appetite” of the disc is satisfied.Existing theories predict the results obtained well at high disc Reynolds numbers, but give greater entrainment rates than experiment at low disc Reynolds numbers. More precise measurements are needed to substantiate these conclusions: in particular the use of a hot-wire anemometer seems essential.