A validation study of the model test method for propeller cavitation noise prediction. (1st October 2020)

• Record Type: Journal Article
• Authors: Park, Cheolsoo; Kim, Gun Do; Yim, Geun-Tae; Park, Youngha; Moon, Ilsung
• Is Part Of: Ocean engineering. Volume 213(2020)
• Publication Date: 2020-10-01
• Subjects: Propeller cavitation noise -- Model test -- Full-scale noise prediction -- Full-scale noise measurement -- Validation test; Ocean engineering -- Periodicals; Ocean engineering; Periodicals; 620.4162
• DOI: 10.1016/j.oceaneng.2020.107655
• Languages: English
• ISSNs: 0029-8018

Abstract

Abstract: Propeller cavitation noise, one of the main sources of ship noise, has recently gained much attention owing to its possible adverse effects on marine life. In order to predict full-scale propeller cavitation noise, a model test method using the large cavitation tunnel at the Korea Research Institute of Ships & Ocean engineering (KRISO) was developed. The standard procedure consists of reproduction of the noise source, noise measurement, postprocessing, and noise scaling. The propeller cavitation is reproduced in the same manner as in the cavitation observation test, and the noise is measured. After correcting the multipath effect and the background noise, the model-scale source level (SL) is estimated. The transfer function (TF), which represents the multipath effect, can be measured using a virtual source (or two sources for the twin propeller). Finally, the full-scale SL is predicted by a scaling method. This paper focused on validation of the TF correction and the scaling methods that most affect noise prediction. Validation tests were performed on two ships: a 14, 000 TEU container carrier with a single propeller and a 176 K LNG carrier with twin propellers. The validation study confirmed the effectiveness of the model test method in predicting full-scale propeller cavitation noise. Highlights: A validation study of the model test method to predict full-scale propeller cavitation noise was performed using a KRISO large cavitation tunnel. A series of model tests was performed, and data were processed in accordance with the standard procedure described in the paper. In addition, full-scale tests were carried out following the procedure of ISO 17208–1. Full-scale data of a 14, 000-TEU container carrier with a single propeller and a 176-K LNG carrier with twin propellers were used for the validation study of scaling methods. In this paper, the following are presented: (1) validation of the SL estimation method using the transmission loss (TL) correction, and (2) evaluation of scaling methods including low-frequency scaling, high-frequency scaling, and Reynolds scaling. To validate the TL correction, a known source (or two sources for the twin propeller) are used instead of the propeller(s). To evaluate the scaling methods, two types of validation studies are performed. First, a series of model tests are carried out at different flow speeds. The source levels at different flow speeds are scaled to a specific flow speed and are compared with each other. Second, full-scale noise measurements are carried out and are compared with the model test results. Validation tests are performed on two ships, each equipped with a single propeller and twin propellers. The validation study confirmed the effectiveness of the model test method in predicting full-scale propeller cavitation noise.