Case Study: VTT Technical Research Centre reduces exhaust noise with MSC Software Actran

Finding the Solution to a Noise Problem

VTT Technical Research Centre of Finland was tasked with solving an intolerable low-frequency noise issue originating from the engine testing facility of their client, Wärtsilä. The challenge was to identify the source of a dominant 94 Hz noise peak from an engine exhaust system that was causing complaints from a nearby residential area, despite overall noise levels being within legal limits. They partnered with MSC Software, using its Actran software for vibro-acoustic modeling to investigate the problem.

MSC Software's solution involved using Actran to create and iteratively refine a computational model of the exhaust system. By expanding the model to include previously overlooked ductwork, they identified a standing wave resonance in the inlet pipe as the root cause. A simple physical modification to the silencer inlet was proposed and simulated, predicting a significant noise reduction. Once implemented, the modification achieved a 20 dB reduction in the problematic noise band and a 10 dB reduction in total noise, effectively solving the issue with minimal physical testing.

VTT Technical Research Centre

Erin Komi

Research Scientist