Abstract:The noise generated by the frost protection wind machine in the tea orchard at night had a serious impact on the surrounding residents, to reduce the aerodynamic noise of the frost protection wind machine of arc-plate blade, a sawtooth noise reduction structure was designed. Taking the length, width, number and position of the sawtooth as the test factors, and the sound pressure level (SPL) at 1m directly in front of the impeller axis and the average wind speed at the outlet surface as the evaluation index, the combination of numerical simulation and response surface method was used to optimize the structural parameters of the sawtooth. The optimization results showed that the significant order of the influence of sawtooth parameters on the SPL was the width, number, length and position of the sawtooth;the significant order was the sawtooth position, width, number and length on wind speed. The optimal parameter combination was the sawtooth length of 26.0mm, width of 11.6mm, number of 16, and position of 480.0mm. The performance test of the sawtooth blade was carried out. The test results showed that the SPL at a distance of 30m from the sawtooth-blade fan was lower than the national standard limit of 45.0dB, and the SPL at the front, rear and radial right points of the sawtooth blade were reduced by an average of 7.71% compared with the control blade. The wind speed distribution trends of the two blade types were similar and both could produce a good temperature rise effect. The maximum wind speeds of control blade type and sawtooth blade type were 3.19m/s and 3.17m/s, respectively, which were both measured at 12m. The average temperature rises of leaf type at 10m and 15m were 2.8℃ and 3.2℃, respectively;the average temperature rise of control leaf type at 10m and 15m were 3.0℃ and 3.1℃, respectively, and there was no significant difference between the two. The sawtooth blade type could effectively reduce the noise of the fan on the premise of ensuring the frost protection performance.
