Problem
Troubleshooting noise and vibration problems can be complex. This example demonstrates a standard acoustic baffle design used in a gas turbine outlet duct. In this case, a low frequency tonal noise was detected with sufficiently violent vibrations as to be a safety and environmental concern.

Solution
Transient computational fluid dynamics (CFD) simulations were performed to evaluate vortex shedding frequencies and subsequent fluid induced baffle loads. The overall goal was to identify the root-cause and develop a cost-effective fix.

Result
CFD models were successful in understanding the cause of vibrations in the duct. The addition of nose cones applied to the baffles eliminated this vibration by controlling vortex shedding of the baffles and removing transverse pressures waves. As a plus, pressure losses across the baffles were halved.