| Budget Amount *help |
¥15,930,000 (Direct Cost: ¥14,400,000、Indirect Cost: ¥1,530,000)
Fiscal Year 2007: ¥6,630,000 (Direct Cost: ¥5,100,000、Indirect Cost: ¥1,530,000)
Fiscal Year 2006: ¥9,300,000 (Direct Cost: ¥9,300,000)
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| Research Abstract |
In operating turbomachinery at off-design conditions, various abnormal flow phenomena occur, resulting in noise and vibration. In order to establish an outstanding technology characteristic of Japan, which can totally suppress these abnormal flow phenomena without dropping total efficiency, the experimental research and the numerical simulations were preceded.
In the fast step of research, inducers were tested, as the most severe cavitation phenomena are usually observed. J-Groove technique was applied to several inducers, and the results showed that the cavitation is suppressed drastically in the low flow range and the suction performance is improved to twice the conventional when the groove is optimized In the high flow range the suction performance can also be improved to 15 times the conventional, when J-Groove is coupled with a swirl stop. Next, the J-Groove technique was applied to centrifugal pumps of semi-open impeller, the suction performance is improved considerably without dropping the maximum efficiency, however in the case of closed impeller J-Groove is difficult to apply because of its shape. Here is proposed a new impeller of semi-closed type with J-Groove, resulting in perfect suppression of performance curve instability without dropping the maximum efficiency, and also in improving suction performance in the high flow range.
In the second step, centrifugal compressor was tested as the most severe surge is usually observed Experiment revealed that J-Groove technique is very effective in suppressing surge and in enlarging surge-margin. From numerical simulations, it was made clear that the initiation of rotating stall of diffuser is of key importance to suppress surge, and that J-Groove technique is successfully applied to suppress the initiation of rotating stall and to enlarge surge-margin to a large extent when it is mounted near the outlet of diffuser, though its effect becomes less when mounted near the inlet of diffuser.
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