Effects of Channel Bed Slope on Energy Dissipation of Different Types of Piano Key Weir

Authors: Munendra Kumar, Deepak Singh

Abstract:

The present investigation aims to study the effect of channel bed slopes on energy dissipation across the different types of Piano Key Weir (PK weir or PKW) under the free-flow conditions in rigid rectangular channels. To this end, three different types (type-A, type-B, and type-C) of PKW models were tested and examined. To document and quantify this experimental investigation, a total of 270 tests were performed, including detailed observations of the flow field. The results show that the energy dissipation of all PKW models increases with the bed slopes and decreases with increasing the discharge over the weirs. In addition, the energy dissipation over the PKW varies significantly with the geometry of the weir. The type-A PKW has shown the highest energy dissipation than the other PKWs. As the bottom slope changed from Sb = 0% to 1.25%, the energy dissipation increased by about 8.5%, 9.1%, and 10.55% for type-A, type-B, and type-C, respectively.

Keywords: Piano key weir, bed slope, energy dissipation across PKW, free overfalls.

References:

[1] M. R. Chamani and M. K. Beirami, “Flow Characteristics at Drops,” J. Hydraul. Eng., vol. 128, no. 8, pp. 788–791, 2002, doi: 10.1061/(asce)0733-9429(2002)128:8(788).
[2] J. Matos et al., “Extreme Pressures and Risk of Cavitation in Steeply Sloping Stepped Spillways of Large Dams,” Water (Switzerland), vol. 14, no. 3, pp. 1–24, 2022, doi: 10.3390/w14030306.
[3] A. Parsaie, A. H. Haghiabi, M. Saneie, and H. Torabi, “Prediction of Energy Dissipation of Flow Over Stepped Spillways Using Data-Driven Models,” Iran. J. Sci. Technol. - Trans. Civ. Eng., vol. 42, no. 1, pp. 39–53, 2018, doi: 10.1007/s40996-017-0060-5.
[4] A. M. Yazdi, S. Abbas Hoseini, S. Nazari, and N. Amanian, “Effects of weir geometry on scour development in the downstream of Piano Key Weirs,” Water Sci. Technol. Water Supply, vol. 21, no. 1, pp. 289–298, 2021, doi: 10.2166/ws.2020.272.
[5] M. Pinto, “Energy dissipation on stepped spillways with a piano key weir : experimental study,” pp. 1–11, 2017.
[6] K. R. Eslinger and B. M. Crookston, “Energy Dissipation of Type a Piano Key Weirs,” 2020.
[7] W. Lantz, B. M. Crookston, and M. Palermo, “Apron and cutoff wall scour protection for piano key weirs,” Water (Switzerland), vol. 13, no. 17, 2021, doi: 10.3390/w13172332.
[8] H. Chanson, “Current knowledge in hydraulic jumps and related phenomena. A survey of experimental results,” Eur. J. Mech. B/Fluids, vol. 28, no. 2, pp. 191–210, 2009, doi: 10.1016/j.euromechflu.2008.06.004.
[9] D. Singh and M. Kumar, “Energy dissipation of flow over the type-B Piano Key Weir,” Flow Meas. Instrum., vol. 83, no. November 2021, p. 102109, 2022, doi: 10.1016/j.flowmeasinst.2021.102109.
[10] F. Bahmanpouri, C. Gualtieri, and H. Chanson, “Flow Patterns and Free-Surface Dynamics in Hydraulic Jump on Pebbled Rough Bed,” Proc. Inst. Civ. Eng. - Water Manag., pp. 1–47, 2021, doi: 10.1680/jwama.20.00040.
[11] S. S. Elyass, “Effect of Channel Slope on Energy Dissipation of Flow for Single Step Broad – Crested Weirs صخلم INTRODUCTION” vol. 16, no. 3, pp. 91–103, 2012.
[12] H. Torabi, A. Parsaie, H. Yonesi, and E. Mozafari, “Energy Dissipation on Rough Stepped Spillways,” Iran. J. Sci. Technol. - Trans. Civ. Eng., vol. 42, no. 3, pp. 325–330, 2018, doi: 10.1007/s40996-018-0092-5.
[13] A. H. Haghiabi, M. R. Ghaleh Nou, and A. Parsaie, “The energy dissipation of flow over the labyrinth weirs,” Alexandria Eng. J., pp. 0–4, 2021, doi: 10.1016/j.aej.2021.08.075.
[14] B. M. Crookston and B. P. Tullis, “Labyrinth Weirs: Nappe Interference and Local Submergence,” vol. 138, no. 8, pp. 757–765, 2013, doi: 10.1061/(ASCE)IR.1943-4774.0000466.
[15] D. Singh and M. Kumar, “Hydraulic Design and Analysis of Piano Key Weirs: A Review,” Arab. J. Sci. Eng., 2021, doi: 10.1007/s13369-021-06370-4.
[16] F. Denys, G. Basson, and J. Strasheim, “Fluid structure interaction of Piano Key Weirs,” Labyrinth Piano Key Weirs III – PKW 2017, pp. 119–126, 2017, doi: 10.1201/9781315169064-17.
[17] J. Lombaard, “Evaluation of the Influence of Aeration on the Discharge Capacity and Flow Induced Vibrations of Piano Key Weir Spillways,” no. March, 2020.
[18] B. M. A. Noori and S. S. Ibrahim, “Effect of Bed and Side Slopes on Flow Measurements in Trapezoidal Free Overfall Channels,” Arab. J. Sci. Eng., vol. 41, no. 10, pp. 4187–4194, 2016, doi: 10.1007/s13369-016-2129-z.
[19] S. A. M. Al-Hashimi, H. M. Madhloom, T. N. Nahi, and N. Al-Ansari, “Channel Slope Effect on Energy Dissipation of Flow over Broad Crested Weirs,” Engineering, vol. 08, no. 12, pp. 837–851, 2016, doi: 10.4236/eng.2016.812076.
[20] S. I. Khassaf, L. J. Aziz, and Z. A. Elkatib, “Hydraulic Behavior Of Piano Key Weir Type B Under Free Flow Conditions,” Int. J. Sci. Technol. Res., vol. 4, no. 8, pp. 158–163, 2015.
[21] J. Merkel, F. Belzner, M. Gebhardt, and C. Thorenz, “Energy dissipation downstream of labyrinth weirs,” 7th IAHR Int. Symp. Hydraul. Struct. ISHS 2018, pp. 508–517, 2018, doi: 10.15142/T32D2V.
[22] S. Jüstrich, M. Pfister, and A. J. Schleiss, “Mobile riverbed scour downstream of a piano key weir,” J. Hydraul. Eng., vol. 142, no. 11, pp. 1–12, 2016, doi: 10.1061/(ASCE)HY.1943-7900.0001189.