A Presentation in 1st NATIONAL CONFERENCE ON INNOVATIONS IN MECHANICAL ENGINEERING On

MODELLING, ANALYSIS & OPTIMIZATION OF RUNNER BLADE OF KAPLAN TURBINE

Click to edit Master subtitle styleBVM Engineering College, Vallabh Vidyanagar, Anand, Gujarat -388120 INDIA

Prepared By : Ashish H.Gupta (100070709008)

Sinhgad Institute of Trchnology, Lonavala, Maharashtra 410401

Guided By : Prof. V.H. Chaudhari4/24/12 NCIME-2012 11

OBJECTIVE:

After this thesis work 1. The mass of the blade would be reduced. 2. The cost of blade would be reduced.

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INTRODUCTION:It was developed in 1913 by the Austrian professor Viktor Kaplan. Kaplan turbine is a propeller-type water turbine which has adjustable blades.Reference: 1st model of Kaplan turbine made by Victor Kaplan.

The Kaplan turbine is a reaction turbine, which means that the working fluid changes pressure as it moves through the turbine and gives up its energy. The head ranges from 10-70 meters and the output from 5 to 120 MW. Runner diameters are between 2 and 8 meters. The range of the turbine is from 79 to 429 rpm.

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CONSTRUCTION:

Diagram provided by: Hydro power plant, KADANA

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Working of Kaplan Turbine:

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LITERATURE REVIEWS:1) Paper1The influence of kaplan turbine runner blade thickness on the stress parameters.

Analyzed the stresses, strength & weight of runner by modifying the blade thicknesses at leading edge (using CFD). For this purpose they analyzed the blades by making two modifications: 1. 90% of current blade thickness. 2. 110% of current blade thickness. They assumed the static stresses on other parts of turbine within permissible limits.NCIME-2012 66

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SUMMARYResults compared with original runner: Modification 1: a) Higher efficiency. b) Lower weight. c) Worsened stress & deformation conditions Modification 2. a) Improvement in stress conditions b) Lower efficiency. c) Heavy.

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Paper 2:"FEM MODELING OF FLUID FLOW FOR KAPLAN TURBINE RUNNER"

FEM modeling of runner blade with FEMLAB program (using MATLAB). FEM analysis was conducted on 2d model of runner on 6 different sections. Click to edit Master subtitle style Maximum pressure values were obtained on front side of blade. In the whole analysis runner speed was not taken into consideration.

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Paper3: "Design of the runner of a Kaplan Turbine for small hydroelectric power plants":

Designed each & every part of Kaplan turbine. Stress analysis of all parts of turbine by using standard equations to withstand various forces acting on turbine.

Stainless steel is best material as it does not corrode under influence of water, therefore the properties are not changed.

The wall thickness of hub is much bigger therefore stress analysis of hub is not necessary.

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Paper 4: "Failure Analysis of a Kaplan Turbine Runner Blade by Metallographic and Numerical Methods

The paper presents the results of the failure analysis of a Kaplan turbine runner blade from a hydropower station in Romania. In order to avoid damages, the blade geometry and the number of blades were varied. Click to edit Master subtitle style In blade geometry the stress relive groove were selected for modification.

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Summary:

A few stress relieve groove geometry were analysed, but did not generate a decreasing of the stress concentrators in admissible limits (smaller than half of yield strength value of the material). In order to decrease the maximal stress value it is necessary to reduce the hydrodynamic loads on the blade. For existing operating conditions (discharge, head, speed, power), the stress decreased by increasing the number of the runner blades.

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Kaplan Turbine:Specifications: Inlet Pressure: Max Head: Min Head: Normal Head: Discharge rate: Runaway Speed: Power: Runner Dia: Hub Dia: : Blade Material: Efficiency:4/24/12

5.5kg/cm2 48.2m 30.77m 43.5m 166.68 m3/s 283 rpm 61.7 MW 7000 mm 4220 mm 6o Stainless Steel (SS316) [E=193.05 KN/mm2] 87%NCIME-2012 1212

Lot of research related to optimization of Kaplan turbine & literatures review concluded that: The wall thickness of hub is much bigger therefore stress analysis of hub is not necessary.[2] The screws, pins, etc parts does not contribute much to weight & cost of turbine. The runner blade design is the main factor for optimizing the Kaplan turbine design. So the runner blade is decided for optimization.

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Runner bladeParameters selected to be varied for optimizing the result : > 1. Material of blade [2] > 2. Runner diameter > 3. Primary chamfer. > 4. thickness at leading edge of blade[1]

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Variations in parameters of Runner blade:1. Variations in material: Current: Stainless steel(SS316) Modifications: Carbon steel, steel: S44400, steel: 304, FE40 2. Variations in runner diameter: Current: 7m Modifications: 6.8-7.2m

Click to edit Master subtitle style 3. variations in primary chamfer . : Current: R25 Modifications: R20-R30 4. Variations in thickness at leading edge: Modifications: -10% to +10% of current radius.

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Result for variation in material:

Stainless steel is found best theoretically as it does not corrode under influence of water, therefore the properties are not changed. Out of all stainless steel, SS316 is the best. Cavitation resistance is normally achieved with additions of a minimum of 13% (by weight) chromium, and up to 26% . The chromium forms a layer of chromium(III) oxide (Cr2O3) when exposed to oxygen. The layer is too thin to be visible, and the metal remains lustrous. The layer is impervious to water and air, protecting the metal beneath.

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Properties of other materials are :

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Modelling of Runner Blade:

Original model of Runner blade of Kaplan Turbine. (1) Primary chamfer, (2) Blade thickness at leading edge, (3) Back plate to be fitted on hub.

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Boundary conditions:

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Meshing of the model:

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Result for variation in material:

Austenite steel

Carbon steel

Sr. No. 1 2 3Ferrite steel

Material Carbon steel Austenite steel Ferrite steel

Stress Parameters (MPa) 8.976*102 8.976*102 8.078*102 2121

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Analysis of runner blade:

Enlarged image of area where maximum stress is 4/24/12developed NCIME-2012 2222

Primary chamfer:

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Variations in Primary chamfer:

Sr. No. Dimensions 1 2 3 4 5 4/24/12 20 mm 22 mm 25 mm 28 mm 30 mm NCIME-2012

Stress Parameters(mpa) 9.926*102 1.035*103 1.346*103 1.031*103 8.149*102 2424

Secondary chamfer:

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Variations in Secondary chamfer:

Sr. No. 1 2 3 4 5 4/24/12

Secondary Chamfer Dimensions Stress Parameters (MPa) 5 mm 10 mm 15 mm 20 mm 25 mm NCIME-2012 5.416*102 4.931*102 4.768*102 4.761*102 4.628*102 2626

Conclusion:1. 2.

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The wall thickness of hub is much bigger therefore stress analysis of hub is not necessary. The screws, pins, etc. parts do not contribute much to weight & cost of turbine. The runner blade design is the main factor for optimizing the Kaplan turbine design. Parameters which affect the runner blade optimization are: Material of blade, runner diameter, stress relief groove and thickness at leading edge of blade. Stainless Steel (i.e. SS316) is found best due to following advantages:It is "soft" compare to other material due to it has high ductility and It is also a good material to resist cavitation. Best back plate chamfer dimensions found was 25mm because it is the value for which highest stress parameters were obtained.

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References:[1] Zoran Markov, Predrag Popovski, Andrej Lipej, Vesko Djeli-Faculties of Mechanical Engg, Skopje (Macedonia)On the influence of Kaplan turbine runner blade thickness on the stress parameters., 2008 [2] Hora Cristina &HoraHorea (University of Oradea "FEM modeling of fluid flow for Kaplan turbine runner "Fascicle of Management and Technological Engineering, Volume IX 2010, [3] Timo Flashopler "Design of the runner of a Kaplan Turbine for small hydroelectric power plants "Tampere university of Applied Sciences. (2007) Pg: 21-49 [4] Centre for Research in Hydraulics, Automation and Thermal Processes, University of Resita, Romania. "Failure Analysis of a Kaplan Turbine Runner Blade by Metallographic and Numerical Methods"-pg: 6366 [5] http://nptel.iitm.ac.in/courses/Webcoursecontents/IIT%-20Kharagpur/Machine%20design1/pdf/Module-3_lesson-2.pdf [6] http://www.azom.com/properties.aspx?Artic-leID=863 Click to edit Master subtitle Proceedings, International Conference Classics and Fashion in [7] "Structural Dynamic Identification of Kaplan turbine blades", style Fluid Machinery, pp. 265-276, Belgrade, 2002. [8] "Stresses of Kaplan Turbine Runner Blade During Transients", Proceedings, XXI IAHR Symposium on Hydraulic Machinery Systems, Lausanne, 2002. [9] V.L. Patel & R.N. Patel. Fluid power Engineering 3rd edition. Pg.: 3.60-3.90

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THANK YOUNCIME-2012 2929

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