VARIATION OF AIR CONCENTRATION IN SKI JUMP JETS
Abstract
Scour always be a significant problem for the stability and safety of a dam. Water jet issued from flip bucket of a dam creates an air-water mixture and finally plunges at the downstream of a dam. Depending on the discharge, total head, thickness of the water body, aeration conditions and geometrical features of the flip bucket, the jet is dispersed in air. It is obvious that air concentration is inversely proportional with the dynamic pressures at impingement area of the water jet coming from the flip bucket of spillway of a dam. Impact of the ski jump jet at the impingement point may be reduced depending on the air concentration of the jet. In this study, experimental and numerical assessments are performed to analyze the distribution of the air into the ski jump jet depending on the dynamic pressures at the impingement point. The impact of the ski jump jet is analyzed and air percentages are defined into the jet according to dynamic pressure measurements using pressure transmitters at the impingement area. By doing so, aeration characteristics and impact values of water jets are revealed to generate reliable scour estimates for future researchers.
Keywords
Air concentration,ski jump jets,dynamic pressure distribution,jet dispersion,numerical solution
Kaynakça
- [1] Khatsuria RM. Hydraulics of Spillways and Energy Dissipators, CRC Press, Taylor & Francis Group, NW, 2005; ISBN: 978-0-203-99698-0.
- [2] Rajan BH, Shivashankara Rao KN. Design of trajectory buckets. J. Irrig. Power India 1980; 37(1): 63–76, ISSN : 0974-4711.
- [3] Heller V, Hager WH, Minor HE. Ski jump hydraulics, J. Hydraul. Eng. 2005; 131(5):347–355, DOI:10.1061/(ASCE)0733-9429(2005)131:5(347).
- [4] Steiner R, Heller V, Hager WH, Minor HE. Deflector ski jump hydraulics, Journal of Hydraulic Engineering 2008; 5(134): 562-571, DOI: 10.1061/(ASCE)0733-9429(2008)134:5(562).
- [5] Chanson H. Air Bubble Entrainment in Turbulent Water Jets Discharging into the Atmosphere, Australian Civil/Structural Engineering Transactions 1996; 1(39).
- [6] Schmocker L, Pfister M, Hager WH, Minor HE. Aeration characteristics of ski jump jets, ASCE Journal. of Hydraulic Engineering 2008; 134(1):90-97.
- [7] Kawakami K. A Study on the Computation of Horizontal Distance of Jet Issued from Ski-Jump Spillway, Proceedings of the Japan Society of Civil Engineers 1973; 1973(219):37-44, Doi: http://doi.org/10.2208/jscej1969.1973.219_37.
- [8] Aydin I, Göğüş M, Altan-Sakarya AB, Köken M. Laleli Dam and HEPP Spillway Hydraulic Model Studies, Hydromechanics Laboratory, Civil Engineering Department, 2012, METU.
- [9] Data Acquisition (DAQ) Software retrieved from: http://turkey.ni.com/
- [10] Launder BE, Spalding DB. The numerical computation of turbulent flows, Computer Methods in Applied Mechanics and Engng. 1974; 3(2):269–289, DOI:10.1016/0045-7825(74)90029-2.