Keywords: Discharge coefficient; Flow efficiency; Free-flow condition; Semi-piano weir; Triangular plan-form weir


Weirs are discharge measurement structures have different geometrical shapes. The performances of
the modified triangular plan form weirs were studied under free-flow condition. Three groups of weirs
were tested experimentally. The first group has a flat top; the second has one slope and the third has two
slopes. Each group has three vertex angles (60o
, 90o
and 120o
) with constant height. The hydraulic
performances of weirs are based on the ability to pass the discharge for certain head flow and on the value
of the coefficient of discharge. The values of discharge and the coefficient were compared with earlier
studies being carried on conventional normal weir, broad crest, triangular plan-form and different
labyrinth weirs. All the groups show better performance than conventional shaped and broad weir. The
magnification of the actual discharge to the discharge of broad crested weir is more than one and the best
one is the first in the third group, while the vertex angle is (60o
) for the second and third group and (120o
for the first. The performance of the third group is better than rectangular labyrinth weirs, and it is
compatible with the triangular labyrinth. The discharge coefficient decreases with the increase of relative
value of the head to the height of weir except for the first group. Equations for predicting coefficient of
discharge are proposed within the limitations of this test.


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Al-dabbagh, Mohammad A. (2018). Evaluation of
Flow Behavior over Broad-Crested Weirs of a
Triangular Cross-Section Using CFD
Techniques. International Conference on
Research in Education and Science,2: 361–67.
Al-Talib, Azza N. (2010). Discharge equations of
broad crested weir with triangular end lip.
Damascus university journal, 27, 41–46.
Azimi, Amir H., and Sara Seyed Hakim. (2019).
Hydraulics of Flow over Rectangular Labyrinth
Weirs. Irrigation Science 37(2): 183–93.
Azimi, Amir Hossein, and N. Rajaratnam. (2009).
Discharge Characteristics of Weirs of Finite
Crest Length. Journal of Hydraulic
Engineering 135(12): 1081–85.
Bijankhan, M., and S. Kouchakzadeh. (2017). Unified
Discharge Coefficient Formula for Free and
Submerged Triangular Labyrinth Weirs. Flow
Measurement and Instrumentation 57: 46–56.
Bos,M.G. (1976). In Discharge measurement
structures. The Netherlands: International
Institute for Land Reclamation and
Improvement ILRI.
Castro-Orgaz, O., J. V. Giráldez, and J. L. Ayuso.
(2010). Critical Depth Relationships in
Developing Open-Channel Flow. Journal of
Hydraulic Engineering 136(3): 175–78.
Castro-Orgaz, O., J. V. Giráldez, and J. L. Ayuso.
(2010). Critical Depth Relationships in
Developing Open-Channel Flow. Journal of
Hydraulic Engineering 136(3): 175–78.
Chow, Te. Ven. MCGrawHiu. (1959) In
Open-channel Hydraulics. Publishing House:
International Student Ed,
Crookston, B. M., and B. P. Tullis. (2013). Hydraulic
Design and Analysis of Labyrinth Weirs. II:
Nappe Aeration, Instability, and Vibration.
Journal of Irrigation and Drainage
Engineering 139(5): 371–77.
Crookston, B. M., G. S. Paxson, and B. M. Savage.
(2012). Hydraulic Performance of Labyrinth
Weirs for High Headwater Ratios. 4th IAHR
International Symposium on Hydraulic
Structures (February): 9–11.
Farid J., Alireza, T., Mahmoud, F. M. and Bina, K.
(2016). Investigation of Water Level Profile
and Stage-Discharge Curve in Labyrinth
Weirs. International Journal of Civil
Engineering and Geo-Environmental, 6, 31–
Göǧüş, M., Z. Defne, and V. Özkandemir. (2006).
Broad-Crested Weirs with Rectangular
Compound Cross Sections. Journal of
Irrigation and Drainage Engineering 132(3):
Goodarzi, Ehsan, JavadFarhoudi, and NaserShokri.
(2012). Flow Characteristics of Rectangular
Broad-Crested Weirs with Sloped Upstream
Face. Journal of Hydrology and
Hydromechanics 60(2): 87–100.
Gupta, K K, S Kumar, and K Kumar. (2015). Flow
Characteristics of Sharp-Crested Triangular
Planform Contracted Weirs.Int. J. Eng. Res.
Technol.(IJERT), 2, 1252–1258.
Henderson, F. M. (1966). In Open channel
flow;P.imprenta: New York.
Hoseini, SeyedHooman. (2014). Experimental
Investigation of Flow over a Triangular
Broad-Crested Weir. ISH Journal of Hydraulic
Engineering 20(2): 230–37.
Hosseini-Teshnizi, Sayedeh Zahra et al. (2019). Effect
of Deploying the Flow Guide Vane in
Upstream of Triangular Duckbill Weirs on the
Efficiency of This Type of Weir in Laboratory Conditions. American Journal of Engineering
and Applied Sciences 12(2): 279–89.
Hosseini-teshnizi, Sayedeh Zahra,
ManuchehrHeidarpour, and SaeidEslamian.
(2018). Experimental Study of Effect of Guide
Vanes on the Discharge Coefficient of
Triangular Labyrinth Spillway. American
Research Journal of Civil and Structural
Engineering 2(1): 1–10.
Jalil, Shaker A, and Sarhan A.Sarhan. (2017).
Performance of Flow over a Weir with Sloped
Upstream Face. ZANCO Journal of Pure and
Applied Sciences 29(3).
Johnson, Michael C. (2000). Discharge Coefficient
Analysis for Flat-Topped and Sharp-Crested
Weirs. Irrigation Science 19(3): 133–37.
Kumar, S, Z Ahmad, T Mansoor, and S K Himanshu.
(2013). A New Approach to Analyze the Flow
over Sharp Crested Curved Plan Form Weirs.
(1): 24–28.
Kumar, S., Z. Ahmad, and T. Mansoor. (2011). A New
Approach to Improve the Discharging Capacity
of Sharp-Crested Triangular Plan Form Weirs.
Flow Measurement and Instrumentation 22(3):
Noori, Bahzad M A, and Naeema T Aaref. (2017).
Hydraulic Performance of Circular Crested
Triangular Plan Form Weirs. Arabian Journal
for Science and EngineeringSeptember (42):
Raftek, G. W. (1900), On the Flow of Water over
Dams. Trans. Am. Soc. Civil Eng. XLIV, 220–
Ramamurthy, Amruthur S and Tim, Udoyara S and
Rao, MVJ. 1988.” Characteristicsof
Square-Edged and Round-Nosed
Broad-Crested Weirs.” Journal of Irrigation
and Drainage Engineering, 114, 61–73.
Rouse, H. (1978). In Elementary Mechanics of Fluids
(Dover Books on Physics); New York: Dover
Shaghaghian, Mahmoud Reza, and Mohammad
TaghiSharifi. 2015. “Numerical Modeling of
Sharp-Crested Triangular Plan Form Weirs
Using FLUENT.” Indian Journal of Science
and Technology 8(34).
Subramanya, K. (2009). In Flow in Open Channels;
Tata McGraw-Hill Education.
How to Cite
JALIL, S. A., JAFAR, R. A., & IBRAHIM, S. S. (2021). EXPERIMENTAL VERIFICATION AND REVIEW PERFORMANCE OF THE MODIFIED TRIANGULAR PLAN FORM WEIR. Journal of Duhok University, 23(2), 490-500. Retrieved from https://journal.uod.ac/index.php/uodjournal/article/view/953