Abstract: As the further development of piano key weir,trapezoidal piano key (TPK) weir is of strong discharge capacity and is slightly influenced by terrain.To study the effect of different sidewall angles on the discharge capacity of trapezoidal key weir,RNG k-ε turbulence model and VOF method was used to simulate the free surface of weirs with five different sidewall angles.Results show that α< 0° has a negative effect on the discharge capacity of TPK weir.The increase of sidewall angle enhances the discharge capacity.When α=9°,the discharge capacity is no longer improved.In addition,the discharge capacity of different overflow fronts was analyzed via numerical simulation,and the internal influence mechanism of sidewall angle on the discharge capacity was revealed.

Key words: trapezoidal piano key weir, sidewall angles, discharge capacity, numerical simulation, hydraulic characteristic