CAJ | 학술논문

运用计算流体动力学技术及声比拟理论研究了离心风机3个不同流量下蜗壳及叶片表面偶极子声源产生的基频噪声.风机内部三维瞬态流场由计算流体动力学模拟得到.根据气动声学的FW-H方程对蜗壳内表面提取偶极子声源,对于叶片噪声利用Lowson公式进行建模.为了使计算模型更符合实际,建立了以蜗壳为界的内外声学直接边界元模型,使用多区域声学边界元模型,考虑蜗壳对声传播的散射作用,内部噪声通过蜗壳的进出口传播到风机外部.结果表明:在非定常流场中,蜗壳表面的压力波动以基频为主,而叶片上的压力波动并没有明显的基频分量;蜗舌是基频噪声的最主要声源;随着流量变大,蜗壳辐射的噪声急剧增加;由叶片产生的偶极子基频噪声比蜗壳小,特别是在大流量工况下.
운용계산류체동역학기술급성비의이론연구료리심풍궤3개불동류량하와각급협편표면우겁자성원산생적기빈조성.풍궤내부삼유순태류장유계산류체동역학모의득도.근거기동성학적FW-H방정대와각내표면제취우겁자성원,대우협편조성이용Lowson공식진행건모.위료사계산모형경부합실제,건립료이와각위계적내외성학직접변계원모형,사용다구역성학변계원모형,고필와각대성전파적산사작용,내부조성통과와각적진출구전파도풍궤외부.결과표명:재비정상류장중,와각표면적압력파동이기빈위주,이협편상적압력파동병몰유명현적기빈분량;와설시기빈조성적최주요성원;수착류량변대,와각복사적조성급극증가;유협편산생적우겁자기빈조성비와각소,특별시재대류량공황하.
The computational fluid dynamics (CFD) technique combined with the acoustic analogy theory is employed to study the blade passing frequency (BPF) noise caused by the volute casing surface dipole and the blade rotating dipole in a centrifugal fan. A 3D unsteady turbulent internal flow is obtained by CFD at three different flow rates. The volute surface dipole is extracted based on the FW-H equation and the blade noise is modeled by the Lowson's formula. The multi-domain direct boundary element method is applied to study the noise propagation including the interior acoustic problem and the exterior acoustic problem, and these two models established are coupled together at the casing inlet and outlet openings. It is considered that the interior noise will spread outside through the casing openings by the sound scattering effect of the casing. The results show that the pressure fluctuation on the casing surface had the clear BPF component while there was no obvious BPF fluctuation on the blade. The volute tongue was the main contributor to the BPF fan noise. In addition, the casing noise strength was increased dramatically with the flow rate and the BPF blade noise was smaller than the casing noise, especially at large flow rates.