Detached Eddy Simulation of the Flow Noise Generation of Cylinders with Porous Cover

Abstract

The use of porous materials is a known method for the reduction of cylinder vortex shedding noise. In a previous experimental wind tunnel study, the noise reducing effect of a modification of circular cylinders with open-porous materials was shown. The cylinder models consisted of a solid core cylinder with porous covers with different material parameters. In order to obtain insight into the flow through the porous materials, the noise generation by such porous-covered cylinders is investigated numerically using Detached-Eddy Simulations. This was done for three different porous material covers as well as for a non-porous reference cylinder at three Reynolds numbers in the critical flow regime. Unlike the observations from the experiments, the numerical results show that fluid enters the porous materials and vortex shedding also takes place at the inner core cylinder, leading to an additional tone in the acoustic far field spectrum. In addition, the porous covers were found to have no effect on the directivity of the aeolian tone and to lead to a notable reduction of the aerodynamic drag.

The internal and external flow fields of a structured porous coated cylinder and implications on flow-induced noise

“…Geyer and Sarradj [4] observed that porous coating of a cylinder actually in some flow conditions strengthened the vortex shedding tone but decreased much of the broadband noise. Their more recent numerical simulations [5] agree with their experimental data. It should be noted that they used far less porous materials than the aforementioned literature.…”

Internal and Near-Wall Flow Fields of a Structured Porous Coated Cylinder and Their Role in Passive Flow and Noise Control

“…Numerical studies of a Porous Coated Cylinder (PCC) have been shown to cause a reduction of tonal noise amplitude and decrease the tone frequency [3][4][5]. Geyer and Sarradj [6] observed that by applying a porous coating to a cylinder can also decrease much of the broadband noise, in agreement with their following numerical simulations [7]. An interesting observation is that Sueki et al [1] experimentally showed that the material type (i.e., comparing a Metal Foam Porous Coated Cylinder (MFPCC) to a Polyurethane Porous Coated Cylinder (PPCC)) had little or no impact on the measured noise reduction.…”

Structured Porous Material Design for Passive Flow and Noise Control of Cylinders in Uniform Flow

“…This research was further investigated, revealing that the porous coating of a cylinder actually in some flow conditions strengthened the vortex shedding tone but decreased much of the broadband noise [9]. Their more recent numerical simulations [10] agree with their experimental data. For comparative purposes, it should be noted that they used far less porous materials than the aforementioned literature.…”