Tip vortex cavitation noise of marine propeller became primary concems to reduce hazardous environmental impacts from commercial ship or to keep the underwater surveillance of naval ships. The investigations of the ti...Tip vortex cavitation noise of marine propeller became primary concems to reduce hazardous environmental impacts from commercial ship or to keep the underwater surveillance of naval ships. The investigations of the tip vortex and its induced noise are normally conducted through the model test in a water cavitation tunnel. However the Reynolds number of model-test is much smaller than that of the full-scale, which subsequently results in the difference of tip vortex cavitation inception. Hence, the scaling law between model- and full-scales needs to be identified prior to the prediction and assessment of propeller noise in full scale. From previous researches, it is generally known that the incipient caivtation number of tip vortex can be represented as a power of the Reynolds number. However, the power exponent for scaling, which is the main focus of this research, has not been clearly studied yet. This paper deals with the estimation of scaling exponent based on tip vortex cavitation inception test in both full- and model-scale ships. Acoustical measurements as well as several kind of signal processing technique for an inception criterion suggest the scaling exponent as 0.30. The scaling value proposed in this study shows slight difference to the one of most recent research. Besides, extrapolation of model-ship noise measurement using the proposed one predicts the full-scale noise measurement with an acceptable discrepancy.展开更多
The tip vortex cavitation（TVC） noise of marine propellers is of interest due to the environmental impacts from commercial ships as well as for the survivability of naval ships. Due to complicated flow and noise fiel...The tip vortex cavitation（TVC） noise of marine propellers is of interest due to the environmental impacts from commercial ships as well as for the survivability of naval ships. Due to complicated flow and noise field around a marine propeller, a theoretical approach to the estimation of TVC noise is practically unrealizable. Thus, estimation of prototype TVC noise level is realized through extrapolation of the model TVC noise level measured in a cavitation tunnel. In this study, for the prediction of prototype TVC noise level from a model test, a novel scaling law reflecting the physical basis of TVC is derived from the Rayleigh-Plesset equation, the Rankine vortex model, the lifting surface theory, and other physical assumptions. Model and prototype noise data were provided by Samsung Heavy Industries（SHI） for verification. In applying the novel scaling law, similitude of the spectra of nuclei is applied to assume the same nuclei distribution in the tip vortex line of the model and the prototype. It was found that the prototype TVC noise level predicted by the novel scaling law has better agreement with the prototype TVC noise measurement than the prototype TVC noise level predicted by the modified ITTC noise estimation rule.展开更多
为了在设计阶段实现推进泵水下低频辐射噪声的测试与评估,在模型泵水力性能测试装置的基础上,提出了基于矢量声强法的模型泵水下辐射噪声对比测试方法,研制了基于二维圆弧面扫描方式的推进泵模型水下辐射噪声测试装置。测试系统采用两...为了在设计阶段实现推进泵水下低频辐射噪声的测试与评估,在模型泵水力性能测试装置的基础上,提出了基于矢量声强法的模型泵水下辐射噪声对比测试方法,研制了基于二维圆弧面扫描方式的推进泵模型水下辐射噪声测试装置。测试系统采用两只一维矢量水听器组成测试线阵,实现模型泵水下辐射声功率的测试与计算。系统测试精度通过标准声源进行验证。结果表明:系统测量的绝对误差不大于±2 d B,重复性误差不大于±1.5 d B。该测试装置为推进泵的噪声控制及研究提供了比对测试试验手段和分析基础,也可为其他模型泵的噪声评估提供参考。展开更多
文摘Tip vortex cavitation noise of marine propeller became primary concems to reduce hazardous environmental impacts from commercial ship or to keep the underwater surveillance of naval ships. The investigations of the tip vortex and its induced noise are normally conducted through the model test in a water cavitation tunnel. However the Reynolds number of model-test is much smaller than that of the full-scale, which subsequently results in the difference of tip vortex cavitation inception. Hence, the scaling law between model- and full-scales needs to be identified prior to the prediction and assessment of propeller noise in full scale. From previous researches, it is generally known that the incipient caivtation number of tip vortex can be represented as a power of the Reynolds number. However, the power exponent for scaling, which is the main focus of this research, has not been clearly studied yet. This paper deals with the estimation of scaling exponent based on tip vortex cavitation inception test in both full- and model-scale ships. Acoustical measurements as well as several kind of signal processing technique for an inception criterion suggest the scaling exponent as 0.30. The scaling value proposed in this study shows slight difference to the one of most recent research. Besides, extrapolation of model-ship noise measurement using the proposed one predicts the full-scale noise measurement with an acceptable discrepancy.
文摘The tip vortex cavitation（TVC） noise of marine propellers is of interest due to the environmental impacts from commercial ships as well as for the survivability of naval ships. Due to complicated flow and noise field around a marine propeller, a theoretical approach to the estimation of TVC noise is practically unrealizable. Thus, estimation of prototype TVC noise level is realized through extrapolation of the model TVC noise level measured in a cavitation tunnel. In this study, for the prediction of prototype TVC noise level from a model test, a novel scaling law reflecting the physical basis of TVC is derived from the Rayleigh-Plesset equation, the Rankine vortex model, the lifting surface theory, and other physical assumptions. Model and prototype noise data were provided by Samsung Heavy Industries（SHI） for verification. In applying the novel scaling law, similitude of the spectra of nuclei is applied to assume the same nuclei distribution in the tip vortex line of the model and the prototype. It was found that the prototype TVC noise level predicted by the novel scaling law has better agreement with the prototype TVC noise measurement than the prototype TVC noise level predicted by the modified ITTC noise estimation rule.
文摘为了在设计阶段实现推进泵水下低频辐射噪声的测试与评估,在模型泵水力性能测试装置的基础上,提出了基于矢量声强法的模型泵水下辐射噪声对比测试方法,研制了基于二维圆弧面扫描方式的推进泵模型水下辐射噪声测试装置。测试系统采用两只一维矢量水听器组成测试线阵,实现模型泵水下辐射声功率的测试与计算。系统测试精度通过标准声源进行验证。结果表明:系统测量的绝对误差不大于±2 d B,重复性误差不大于±1.5 d B。该测试装置为推进泵的噪声控制及研究提供了比对测试试验手段和分析基础,也可为其他模型泵的噪声评估提供参考。
