Development Of Engine Noise Test And Analysis System Based On Virtual Instrument

With the development of the Lightweight, High-speed and Integration, there have more challenges to control noise of the Engine. Engine radiated noise into surrounding, which have an effect on people’s sleepy and working efficiency. Auditory organ also can be damaged by high decibel noise and there will be dizziness, headache and other physiological effects in the high intensity noise surrounding for a long time, therefore, it’s very important to control the engine noise. The main noise sources must be isolated and identified and the noise signal’s characteristics of time and frequency must be researched before controlling to engine noise, therefore, it’s very necessary to develop a system for engine noise testing and analysis.For the content of engine noise testing and analysis system, the development of domestic and foreign noise test technologies were systematic analyzed and the advantages of combining virtual instrument technology was put forward, deeply studied the basic method of building the test system and developed a system for engine noise testing and analysis. Analyzed and deduced the wavelet analysis, the near-field acoustic holography and the partial coherence algorithm based on the noise test and analysis technology. On this basis, the test and analysis system was divided into hardware and software system combined with the virtual instrument technology. An automatic mobile control line array device was designed, which with the microphone, the PXI4498 data acquisition card made up the hardware system; for software system, programmed the frequency domain analysis system, time frequency analysis system based on FFT transform acoustic holography, and phase offset stem algorithm system through the virtual instrument development platform, built a testing platform including near field acoustic holography and nine sound power level testing.In order to verify the practical and effective of the engine noise testing and analysis system, near field acoustical holography tested the YN38CRD2 under the two kinds of working condition (1600 r·min-1 and 1800 r·min-1), analyzed the noise signal’s spectrum and continuous wavelet through the testing and analysis system’s time and frequency module. The results show that:under the 1600 r·min-1, the main energy of engine noise distributed in the range of 0-220Hz,300-850 Hz,1000～1150 Hz,1150～1600 Hz,1900～2110 Hz and 2200～2600 Hz. Under 1800 r·min-1, the main energy of engine noise distributed in the range of 0～250Hz,400～700 Hz.700～2000 Hz and 2000～2600 Hz. rebuilt the sound pressure level of the reconstruction surface for advantage dominant frequency, and the experimental results verified the acoustic holography technique can effectively separate the main sound source in the engine noise testing and analysis system. At the same time, used 9 point sound power level tested the 4100QB diesel engine at the idle condition in a semi anechoic chamber based on the 《B/T 1859 reciprocating internal combustion engine radiation measurement of airborne noise engineering method and simple method》, the results show that the system can meet the practical engineering application for enterprise.