International Journal of Engineering Research & Science (IJOER) ISSN: [2395-6992] [Vol-2, Issue-6 June- 2016] Page | 129 Energy Loss Analysis of 3D Asymmetric Trifurcations Using CFD Nagappa Pattanashetti 1 , Manjunatha S.S 2 1 M.Tech Student- Department of Mechanical Engineering, Government Engineering College, Devagiri, Haveri – 581110, Karnataka, India. Mobile: +91 98 80 112696 [email protected]2 HOD- Department of Mechanical Engineering, Government Engineering College, Devagiri, Haveri – 581110, Karnataka, India. [email protected]Abstract— Head losses are very common in penstock trifurcations. In this paper, six cases of 3D asymmetric trifurcations have been modeled with main pipe length & diameter of 1.3716m & 0.0254m, respectively and branch pipe lengths & diameters of 0.762m & 0.0196m, respectively. Volumetric flow rates, velocity magnitudes, dynamic and total pressure contours and their values have been computed. Energy loss coefficients have been computed for branch pipes for an input air velocity of 3m/s by pressure data obtained from the CFD analysis. The maximum values of velocity magnitude, dynamic and total pressures are observed in the branch-2 and head losses in branch-2 are relatively less. Keywords— Head losses, Energy loss coefficients, 3D asymmetric trifurcations. I. INTRODUCTION In penstocks used for hydropower projects, trifurcations along with the other components, help in producing electricity. These trifurcations supplement water supply to multiple turbines at the same time. Despite having the economical advantage over independent systems, even this system is not free from losses. The comparison of velocity magnitudes, dynamic and total pressure contours and determination of head loss coefficients in the branch pipes sums up the interest of this study. II. DOMAIN A total of six cases have been modeled using Gambit 2.4.6, with each model displaying an asymmetry about the central branch axis. The dimensions used for the six cases in the current analysis are shown in the table 1. TABLE 1 DIMENSIONS OF ASYMMETRIC TRIFURCATIONS Dimensions In Meter Length of Main Pipe (L) 1.3716 Diameter of Main Pipe (D) 0.0254 Lengths of branch pipes (l 1 , l 2 , l 3 ) 0.762 Diameters of branch pipes (d 1 , d 2 , d 3 ) 0.0196 The angle between the branch-2 and branch-1 is termed “α” and the angle between the branch-2 and branch-3 is termed “β”. The angles used for the six cases are shown in the table 2. TABLE 2 ANGLES “α” AND “β” FOR THE SIX CASES Case No. 1 2 3 4 5 6 Angle “α” in Degrees 5 10 15 10 15 20 Angle “β” in Degrees 10 15 20 5 10 15 A model created using Gambit for the case 2 of this study is shown in figure 1. Mesh of T-Grid type using Tet/Hybrid elements was generated for all the six cases in Gambit. A typical mesh generated for the case 3 of this study is shown in figure 2
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Energy Loss Analysis of 3D Asymmetric Trifurcations Using CFD
Abstract— Head losses are very common in penstock trifurcations. In this paper, six cases of 3D asymmetric trifurcations have been modeled with main pipe length & diameter of 1.3716m & 0.0254m, respectively and branch pipe lengths & diameters of 0.762m & 0.0196m, respectively. Volumetric flow rates, velocity magnitudes, dynamic and total pressure contours and their values have been computed. Energy loss coefficients have been computed for branch pipes for an input air velocity of 3m/s by pressure data obtained from the CFD analysis. The maximum values of velocity magnitude, dynamic and total pressures are observed in the branch-2 and head losses in branch-2 are relatively less.
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International Journal of Engineering Research & Science (IJOER) ISSN: [2395-6992] [Vol-2, Issue-6 June- 2016]
Page | 129
Energy Loss Analysis of 3D Asymmetric Trifurcations Using CFD Nagappa Pattanashetti
1, Manjunatha S.S
2
1M.Tech Student- Department of Mechanical Engineering, Government Engineering College, Devagiri, Haveri – 581110,
Karnataka, India. Mobile: +91 98 80 112696
[email protected] 2HOD- Department of Mechanical Engineering, Government Engineering College, Devagiri, Haveri – 581110, Karnataka,