Author(s): M. Oertel; B. Belay; X. Shen; H. Willems

Linked Author(s): Mario Oertel

Keywords: Discharge coefficients; Large-scaled model; Piano key weir; 3D printing

Abstract: Piano key weirs (PKW) are novel hydraulic structures, characterized by an increased discharge capacity, compared to regular weirs. Through the last decades, experimental studies have mainly focused on efficiency aspects and design regulations. Therefore, often small scaled experiments were conducted in hydraulics laboratories in which model geometries were produced with materials like acrylic glass. But also in recent practices, 3D printing techniques are being used to plot small-scaled piano key weir configurations up to 30 or 40 cm width. The present investigation focuses on a large-scale 3D printed PKW with a total width of 1 m featuring quarter round crest shape in upstream direction. The weight of the printed structure is approximately 30 kg and 8 days continuous plotting process were necessary to produce the weir – consequently, it is the largest 3D printed PKW up-to-date. The plotted PKW was installed at Helmut-Schmidt-University’s new hydraulics laboratory within a 20 m long and 1 m wide flume. Discharges ranging from 20 to 330 L/s were used to investigate the hydraulic performance of this printed PKW with a height of 4 cm. Results depict that the scale difference between models of 30 cm and 40 cm in height is not significant if the objective is to study discharge coefficients. 30 cm models can reproduce similar flow properties at a relatively smaller cost and less preparation time. Moreover, patterns of nape detachment were observed at the downstream crest lip, indicating the influence of the printing layer height in inducing undesired flow separation for relative upstream heads above 0.33 that could likely affect the nape trajectory.

DOI: https://doi.org/10.26077/6d47-2e35

Year: 2022