By means of test research, a small sized inlet with a symmetrical bell-mouth form instead of traditional large sized one will be adopted for the TGP's hydropower station.

The sand retention apparatus is composed of an upper joint (1), a central tube (2), a retention ring (3), a sealing element (4), a spacing ring (5), an adjusting ring (6) and a bell mouth (7).

The bell has a specific name of the site, known as moving the upper and the lower part is called the drum bell mouth 16.20 for milling, bell onthe lips say, Name-minute dance.