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Research on Measurement Method of Aerodynamic Noise of Muffler
ISSN: 0148-7191, e-ISSN: 2688-3627
To be published on April 14, 2020 by SAE International in United States
With the development of high-speed internal combustion engines, aerodynamic noise has become a major factor in reducing the performance of muffler. Based on the two-microphone transfer function method and static transmission loss of mufflers, this paper proposes a measuring method to detect the aerodynamic noise of the muffler. On the built-in muffler aerodynamic noise test bench, a special sampling tube was designed to measure the aerodynamic noise of the muffler at different flow velocity. For the sound absorption end with large reflection coefficient, the test and simulation data have a large error at low frequency. To cope with this problem, a correction formula is derived to eliminate the reflection of sound waves at the end of the test pipeline and form multiple reflections in the upstream and downstream. The test results of the muffler on the test bench show: The aerodynamic noise data obtained by the sampling pipe is basically consistent with the simulation results by means of leading out measurement, which realizes the measurement of high noise in the pipe by an ordinary sensor. The correction formula can effectively eliminate the influence of the reflected wave caused by the end load on the calculation of the transmission loss, reduce the performance requirements of the end sound-absorbing material, and ensure the accuracy of the aerodynamic noise measurement.