Abstract Papaya spillway, mixing the piano key weir principles on a shaft spillway was tested in this research. Overall 80 experiments were conducted using physical models. Three models of papaya spillway with different angles were tested and experiments data were analyzed. This paper is devoted to explain about effects of using piano key inlet on shaft spillway on circulation number. Comparison between three papaya models showed that papaya model with an angle of 90 degrees has minor circulation number so that it has minor circulation strength compare with other models. As a result, it can pass higher amount of discharge through the shaft. In other words, papaya model with an angle of 90 degrees has better performance beyond comparison.

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