论文部分内容阅读
It is shown from both the numerical calculation and experimental research in flow ducts with an absorbing wedge at ekit that there does exist considerable noise reduction using single bypass added to the main duct, but the amount and spectrum of noise reduction sometimes are not satisfactory in practice. Furthermore, the exit of practical duct is always connected with atmosphere directly so there is not any absorbing wedge at exit. In order to resolve these two problems, a method for predicting the noise reduction in practical ducts using multiple bypasses and numerical samples are presellted in the paper. It is proved correct by a site test, and there is noise reduction of 5 dB(A), even though the site test is not under the optimum situation.
It is shown from both the numerical calculation and experimental research in flow ducts with an absorbing wedge at ekit that there does exist great noise reduction using single bypass added to the main duct, but the amount and spectrum of noise reduction sometimes are not satisfactory in practice . The exit of practical duct is always connected with atmosphere directly so there is not any absorbing wedge at exit. In order to resolve these two problems, a method for predicting the noise reduction in practical ducts using multiple bypasses and numerical samples are presellted. in the paper. It is proved correct by a site test, and there is noise reduction of 5 dB (A), even though the site test is not under the optimum situation.