论文部分内容阅读
阐述了采用空化黏流CFD瞬态模拟和脉冲球形气泡辐射噪声理论相结合的思路在螺旋桨空化低频噪声谱预报上的应用方法。预报了全附体SUBOFF潜艇标称伴流条件下的NSRDC4383五叶大侧斜桨和某七叶大侧斜桨的片空化低频噪声谱,分析了桨叶负载和空化程度对线谱成分及其谱源级的影响。空化模拟时采用作者提出的且可信性经过验证的改进Sauer空化模型和修正SST湍流模型。噪声谱预报时空化体积由空化特征长度求取,较空泡表面球形等价假设更加合理。计算表明,七叶桨较五叶桨的确具有负载小、空化初生延迟、空化低频线谱噪声低的特征。在相同的基于航速的空化数下,非均匀进流与桨叶相互作用会明显增加线谱成分及其谱源级。在伴流、空化数和转速一定时,随着负载减小,推力、力矩和桨叶空化面积均会减小,但空化体积加速度幅度却变大,离散线谱噪声级增加且由奇次谐频为主转变为以偶次谐频为主;当仅减小空化程度时,谐频线谱成分明显被抑制,且1 kHz频率处谱源级减小2.54 dB。较完整地构建了螺旋桨空化水动力和噪声性能评估的数值平台,可用于指导艇尾低噪声桨的数值设计。
The application of the combination of cavitation viscous flow CFD transient simulation and pulse spherical bubble radiation noise theory in the prediction of low frequency noise spectrum of propeller cavitation is described. Prediction of cavitation low-frequency noise spectrum of NSRDC4383 large side slant and some big side slant of NSRDC4383 with full attachment SUBOFF submarine under nominal condition, and analyzed the influence of blade load and cavitation on line spectrum composition And its source-level impact. The cavitation simulation uses the improved Sauer cavitation model and the modified SST turbulence model proposed by the authors and verified in credibility. The noise spectrum predicts that the space-time volume is calculated from the length of the cavitation feature, which is more reasonable than the spherical equivalent assumption on the surface of the bubble. Calculations show that the seven-blade propeller has the characteristics of small load, cavitation primary delay and low cavitation low-frequency spectral noise. Under the same velocity-based cavitation number, the non-uniform inflow and blade interaction significantly increase the line spectral composition and its spectral source. When the entrainment, cavitation number and rotational speed are constant, as the load decreases, the thrust, moment and blade cavitation area will decrease, but the cavitation volume acceleration amplitude will increase and the discrete line noise level will increase However, when only the cavitation degree is decreased, the harmonic spectrum component is obviously suppressed, and the source level at 1 kHz is reduced by 2.54 dB. The numerical platform for evaluating aerodynamic and aerodynamic performance of propeller cavitation hydrodynamics can be constructed more completely, which can be used to guide the numerical design of low noise propeller.