The experiments on resistance reduction of a medium-size and a large-size gyroidal models were respectively carried out in a towing tank and a large circulating water channel, and the effects of air injection forms, air flow rates and injection pore size on the resistance reduction rate, propulsion performance, and radiative noise reduction were discussed. Some conclusions can be drawn as follows:the air injection at the bow of the gyroidal body can restrain radiative noise and reduce total resistance effectively, but decrease the propulsion performance; however, the reduction rate of propulsion performance by bubbly layer is close to that of resistance. At the same air flow rate and same velocity of water, the resistance reduction with air injection at the bow is better than that both at the bow and at the middle of the body. The factors such as velocity, air flow rate, and model size have significant influence on resistance reduction rate by bubbly layer. The resistance reduction rate of the medium-size model is about 11％ at Fr＞1.13. Then there is a saturated air flow rate, below which the resistance reduction increases with air flow rate rising and vice versa. When model size increases, the reduction rate decreases to some degree. The maximum resistance reduction rate of the large model with the length of 4. 17 m and the maximum diameter of 356.3 mm is about 4％ within 0.95＜ Fr＜l. 59. The resistance reduction rate with 0. 5 mm pore is higher than that with 1.0 mm pore.%在拖曳水池及大型循环水槽中,分别开展了中尺度及大尺度回转体模型喷气减阻试验研究,初步探讨了喷气方式、气流量、喷孔尺度变化对减阻率、推进性能及辐射噪声的影响规律.结果表明:回转体首部喷气能有效抑制辐射噪声、降低总阻力,但会引起推进性能的下降,推进性能下降率接近于减阻率.首部单独喷气的减阻效果优于首部、中部联合喷气的减阻效果;来流速度、气流量以及模型尺度对减阻率的影响较大,Fr＞1.13时,中尺度模型减阻率可达11%,存在饱和气流量,气流量小于饱和气流量时,减阻率随气流量的增加而增大,反之则减小.模型尺度增大时,减阻率有所下降,在试验的速度范围(0.95＜Fr＜1.59)内,长度4.17 m、最大直径356.3 mm的大尺度模型的最大减阻率约为4%.0.5 mm喷孔的减阻率高于1.0 mm喷孔的减阻率.
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