3d布置与9点布置对发动机声功率测量的不确定度影响

3d and 9 Measurement Points Affecting the Uncertainty in Sound Power Level Measurement

通过对不同测距3d布置与9点布置的测点布置不确定度的试验研究及试验室环境修正的测量,建立了测点布置不确定度、试验室环境修正与声功率级不确定度的关系式,比较了3d布置及9点布置的声功率级测量不确定度。研究结果表明:验证样机采用3d布置所有测距测量不确定度均满足工程法要求;采用9点布置较小测距时,测量不确定度大于1.5dB,不满足工程法要求;3d布置环境适用范围优于9点布置。

By experimental study of the measurement uncertainties at 3d（d measurement distance） and 9 microphone positions and the environmental correction for laboratory test, the relationship between the measurement uncertainties at different microphone positions, the environmental correction for laboratory test and the uncertainty in sound power level measurement was established, comparing the uncertainties in sound power level measurement at 3d and 9 microphone positions with each other. Validation test of the engine prototype shows that the measurement uncertainties at all measurement distances comply with the requirements specified in the engineering method when using 3d layout. But it does not meet the requirements of the engineering method when using 9 microphone positions with measurement uncertainty more than 1. 5 dB. To sum up, 3d microphone position measurement suits the environmental conditions better.