Dhakrani RMU Project – Model Test
Introduction
This article aims to describe the model testing carried out by Jaberg and Partner GmbH at Institute of Hydraulic Fluid Machinery (HFM) laboratory, Graz University of Technology, Austria, for the Dhakrani HEP RMU Project in India. Jaberg and Partner are leading experts for fluid technology in application oriented for turbines and was commissioned by FLOVEL to develop a new Kaplan turbine to suit the RMU requirements.
About the project
The Dharkrani HEP was originally commissioned in 1965/1966/1970 with Litostroj Power make Turbines (Yugoslavia). The project is owned and operated by Uttarakhand Jal Vidyut Nigam Limited (UJVN Ltd.), Uttarakhand, India. The supply is equipped with replacement of three units of Kaplan machines, running at synchronous speed of 187.50 rpm, operating under rated net head of 19.6 m. After renovation the Dhakrani HEP will generate an output of 3 x 11,250 kW with 10% upgradation.
Reverse Engineering
Reverse Engineering of the existing water passages was carried out using scanning technology of surfaces at site and original Litostroj drawings as reference only.
A 3D drawing of water passages for CFD simulation purpose was prepared and checked to ensure the reproduction of existing passages within the hydraulic tolerances defined in IEC 60193.
CFD Studies and Hydraulic Design
The application of a new runner and distributor in the existing water passage was extensively studied and verified through CFD analysis. The new runner was based on state-of-the-art technology.
Model Design and Manufacturing
The model was designed and manufactured in Europe by Jaberg and Partner. The spiral casing and draft tube elbow were manufactured out of Aluminium blocks with high precision CNC milling. All components were finally inspected using modern CMM technology.
Model Test
In accordance with the contract, a homologous model acceptance test as per IEC 60193 was conducted to verify the hydraulic performance guarantees that are crucial for the long-term operation of the units.
The main hydraulic performance characteristics in regards of efficiency, power, cavitation, runaway, and axial thrust have been preliminarily tested. Complementary tests were made for wicket gate and runner blade torque.
UJVN Ltd. attended the witnessed part of the model test performed in Graz, Austria. During that time the test was also witnessed online from FLOVEL and UJVN Ltd. Head Offices located in Faridabad and Dehradun respectively, both locations in India. The tests were concluded in April 2023.
All test results from the preliminary and witnessed tests were compiled in a final report.
Observations and Conclusions
After the completion of model test for Dhakrani HEP, the hydraulic design validation was done based on the observation that:
- A witnessed model test has been performed where hydraulic efficiency, power output, runaway speed and cavitation performance have been compared with the guaranteed values given in the contract.
- The results showed that the power and efficiency at each guaranteed point and the guaranteed weighted average efficiency was fulfilled.
- The results also showed that the maximum measured stead state runaway speed is lower than the guaranteed value.
- Considering that the prototype turbine is manufactured to the designer’s high-quality standards and based on model geometry, and that the turbine operates strictly within the design operating range, the cavitation observed during the tests would not exceed the guaranteed value.
- UJVN Ltd. accepted the model test results and approved for further manufacturing of the prototype turbine.
About FLOVEL:
FLOVEL name has been synonymous with the hydro power sector for over four decades. FLOVEL is a full-line supplier of electromechanical equipment and services for small and medium size hydro power plants manufacturer of hydraulic turbines, valves and turnkey supplier of electro mechanical packages for hydro power projects and ranks amongst the leading players globally. FLOVEL manufacturers complete range of Pelton, Francis, Kaplan, Axial Flow turbines and Valves for hydropower projects. The strength of FLOVEL is in its ability to offer all-inclusive solutions (Electro Mechanical-Turnkey Packages).
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