Effect of High Polymer Additives on Diffuser Separation Flow Noise

摘要

Tests were made with Polyox, Guar Gum and tap water for different flow conditions. The results with tap water for parallel walls showed fair agreement with the results of other investigators. The most significant results were those of overall sound-pressure level SPL for different flow regimes, power spectral density as a function of frequency and visual observations of flow types. In the region of marginal separation the Polyox and Guar Gum additives, in small concentrations, reduced the flow noise below that of tap water; reductions of up to 10 decibels were found. The acoustic energy was primarily in the low frequency region below 200 cycles per second. In the marginal separation region the additives reduced the power spectral density values significantly below that of tap water. For the region of no separation, the SPL for Polyox and Guar Gum was slightly above that for tap water. For the regime of definite separation, Polyox and Guar Gum gave SPL values essentially the same as that of tap water. (Author)