computational and experimental study of an ultra-low head turbine
DESCRIPTION
The challenge of the limited energy and the need of the time have been always been motivative towards the development of the small hydro-power in the country like, Nepal. It’s obviously the concerned thing to get noticed towards the utilization of the small level rivers and the canals for the energy generation purposes. Investigations have been made for the feasibility study of the usage of the Ultra-low head turbine for the purpose of the energy generation in the unutilized site of our country Nepal. The favored research result in the development of three model for the purpose of the testing the working principle of this turbine. The availability of the site with the low head in adequate amount in our country signifies the positive feasibility towards its possible development.Despite the large possibility of the development it had been always the essential thing to have knowledge about the system of the profile of the blades required for the purpose of efficiency. As the experimental testing for the optimization of the profile of the blades has been rarely possible and the analytical solution for this purpose had been the efficient method of selection of the profile for the increased efficiency the computational study of the turbine with the blade profile of three types was adapted to find out the best one. Flow simulation is performed in the 3D model of all the turbine using ANSYS CFX and the analysis of result on three profile shows the streamline pattern, pressure contour and the torque variation. The comparison on the basis of the torque and the flow visualization help us to select the appropriate design profile of the blades to be imparted on the practice. The variation of the flow and the comparison of the torque through the computational analysis shows the preference of the curve blade profile over twisted and the straight one. The new concept of the ULH has now got a direction for the actual practical physical testing.TRANSCRIPT
PowerPoint Presentation
End Semester Project PresentationON Computational and Experimental Study of an Ultra Low Head Turbine
Group Members:Nischal Pokharel (41102)Pradeep Parajuli (41098)Pratik Koirala (41117)Under the Supervision of:Prof. Dr.- Ing. Ramesh Kumar MaskeyPresentation OutlineUltra low head(ULH) turbine : IntroductionBackground and status Objectives and scope of study Operational PrincipleMethodologyNumerical process adapted Result and the analysisConclusion and future works References
Ultra low head(ULH) turbine : Introduction
Ultra low-head turbineHead : less than 5 mApplicable in even natural or man-made rivers and canals with little or no water storage capacityStatic pressure difference principlePossibilitiesStatus and current ResearchResearch done in the country like Germany, Italy, UK etc.Research paper of University of Southampton.Consultation : Dr Gerald MllerSenior Lecturer. University of Southampton
BackgroundSuccessful modification of our model5ObjectivesTest setup building and testing to measure various parameters6Scope and the limitation.
Flow visualization through similationBUTVelocity triangle analysis.Analysis at optimized angle of 20 degreeAlteration of the angle between blades and the hubAnalysis at different profile of blades.Analysis at optimized canal system.MethodologyLiterature reviewFamiliarization with simulation tools 3D Design in solidworks CFD analysisResult analysis of different profileANSYS CFX softwareSelection of the best on comparrison of the torque and the velocity distribution.8
Contd..Counteracting force due to acclerationForce due to pressure differenceNumerical Process Adapted3D design of turbine with three different blades profile2. Domain3. WorkflowNumerical Process Adapted3D design of turbine with three different blades profile2. Domain3. WorkflowMesh generation PreprocessingSolver controlThree model with three blade profile:
Profile curved that favors the streamline flow.Profile of blades that the aim of generating the concept of the lift, smooth fluid motion and less vibration.Profile of the blade straight.Numerical Process Adapted3. WorkflowMesh generation PreprocessingSolver control3D design of turbine2. DomainMultiphase domain is created
Rotary domain Stationary domain
Numerical Process Adapted2. DomainMesh generation PreprocessingSolver control1. 3D design of turbine3. Work flow
Mesh generation Hex dominant Element size : 0.005 m for stationary domain and 0.004 m for rotating domain
S.NTypes of turbine modelsTypes of domainNumber of Nodes Number of Elements1.StraightStationary280852272132Rotating1445351729882.TwistedStationary280852272132Rotating1419671747213.CurveStationary294614282302Rotating159242191413
PreprocessingInitial and boundary conditions for the flow are defined.
Turbulence modelk-EpsilonInlet conditionAbsolute velocity1.467 m/sFluid valuesWater = 1, Air at 25oC = 0 Outlet conditionStatic pressure1 atmOpening condition in rotating domainOpening Pressure and Direction1 atmFluid valuesWater = 1, Air at 25oC = 1Solver ControlConvergence controlMinimum iteration1Maximum iteration300Convergence criteriaResidual typeRMSResidual target1.E-4Result and the discussionConvergence History(Torque)
Velocity Distribution
Pressure Distribution
Torque comparisonForces along the axis of rotationProfile of the bladeStraightTwistedCurvedForces along the axis of rotationBlade 153.07972.46107.927Blade 25.97886.16227.665Blade 3195.83573.70933.42Blade 490.54235.07426.67Blade 5111.48737.1470.97Blade 6295.29361.4473.906Blade761.55639.47109.303Blade 88112.07443.373hub255.78854.79382.15Total force1150.558472.3131475.384Torque97.7974340.14661125.4076Efficiency0.3876240.1591220.497058Assumption : The resultant force act at the mid-poinnt of the blade.Gantt Chart
Conclusion Among all the turbine differing in the blade profile the curved blade profile has been found most efficient.
ReferencesSenior, J., Wiemann, P., & Muller, G. THE ROTARY HYDRAULIC PRESSURE MACHINE FOR VERY LOW HEAD HYDROPOWER SITES. University of Southampton, U.K.Harvey, A, & Brown, A (1992). Micro-Hydro Design Manual.Stockholm: ITDG Publishing.WIEMANN, P. (2006) Neue wirtschaftliche und technische Mglichkeiten der Stromerzeugung durch innovative Kleinwasserkraftwerke (New economic and technical possibilities for energy generation with innovative small hydropower converters, in German), Diplomarbeit, Universitt Kalsruhe/ University of Southampton.Sayma, A. Computational Fluid Dynamics.Abdulnser sayma & Venus Publishing Aps.2009Andersson, B.& Co., Computational Fluid Dynamics for Engineers, Cambridge University Press.2012Ferziger, H.&Peric,M,. Computational Methods for Fluid Dynamics.3rd, rev. edition 2002Rygg, J.,CFD Analysis of a Pelton Turbine Using OpenFoam,NTNU,2013
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