Land Gas Turbine Exhaust Noise

Abstract

An acoustic test program on a 1/7-scale model of the exhaust configuration for a General Electric MS 5000 gas turbine has been carried out. The tests were designed to isolate the noise contributions of the individual exhaust system components and to identify the additional noise due to combinations of two or more components. This model of the MS 5000 system was found to have three principal noise sources. At a high degree of turbine exit swirl all three sources appear with the most dominant due to an interaction between aft bearing support strut wakes and downstream exhaust hood turning vanes. At zero swirl the isolated turning vane noise and an exhaust hood plenum resonance are the remaining principal noise sources. A rather unexpected effect was uncovered in the course of this program; a strong reduction in the noise generation of separated flow downstream of struts and vanes was observed when a diffuser was placed immediately behind the strut or vane exit plane. This reduction in noise was much greater than could be attributed to the reduction in velocity caused by the diffuser.