Combustion‐Generated Noise: An Environment‐Related Issue for Future Combustion Systems

Authors:
Publisher website
Google Scholar
Abstract
A first‐order estimation of the prediction of combustion‐generated noise from turbulent premixed flames was explored. The method was based on Lighthill's acoustic analogy and used measurement data from high‐speed imaging of chemiluminescent emissions as input. To determine the noise‐generating source, that is, the overall heat release rate from the measured chemiluminescence signals, numerical simulations were performed for 1 D laminar and 3 D turbulent freely propagating flames by employing detailed transport models and reaction mechanisms, including the full reaction chain of the electronically excited hydroxyl radical (OH*). It was shown for both the 1 D and 3 D cases that the local generation of OH* correlated strongly with the heat released from the chemical reaction, especially in the fuel‐lean range. As the chemiluminescence measurements gathered light only along the viewing direction, the line‐of‐sight summed values of heat release rate and OH* concentration were evaluated from the 3 D simulation, and a quasilinear relationship was identified for these integral values. Hence, a proportionality relation was applied for computation of the integral heat release from measured chemiluminescence intensity. An analytical solution of Lighthill's wave equation served as a transfer function, which took fluctuations in the total heat release rate or light intensity as input to calculate the sound radiation in the far field. This approach was applied to a generic burner operated with premixed methane/air jet flames. Good quantitative agreement was obtained between the sound pressures derived from the chemiluminescence measurements and the microphone data, which highlights the potential of the method for applications to more complex flame configurations.
Funding Information
  • DFG - Deutsche Forschungsgemeinschaft (DFG-BO693/27, DFG-PA920/12)

This publication has 31 references indexed in Scilit: