Comparative investigation of the noise emission by armatures under air flow using several noise reducing secondary measures

The status of primary and secondary measures for the reduction of noise emission by flowed-through armatures is presented. The noise emission by three different armatures including the connected test section were investigated for several stroke settings and flow rates. The obtained thresholds show satisfactory agreement with the values expected according to the guideline VDMA 24 422. The noise reduction due to single and combined secondary measures confirms the picture of the noise production mechanism. Each reduction measure has to be evaluated apart. Obstacle masses, outer insulation, and wall reinforcements have only a limited effect, while measures with an influence on the flow can realize high reductions.