Sholayar R&M Project – Model Test
This article aims to describe the model testing carried out at Vattenfall AB R&D facilities in Älvkarleby, Sweden, for the Sholayar R&M Project in India.
About the Project
- The Sholayar HEP was originally commissioned in 1966 with Litostroj Power (Yugoslavia) make Turbines.
- The project is owned and operated by Kerala State Electricity Board (KSEB), Kerala, India.
- Renovation and Modernization Project started on June 2015.
- The supply is equipped with replacement of three units of Francis machines, running at synchronous speed of 750 rpm, operating under rated net head of 303 m. The units after renovation and uprating can generate output of 19.800 kW.
Reverse Engineering of the existing water passages (spiral casing, stay vanes and draft tube) was carried out using scanning technology of surfaces at site and reference of original Litostroj drawings. A 3D drawing of water passages for CFD simulation purpose was prepared.
CFD Studies and Hydraulic Design
- Existing water passages with new runner and distributor was carried out using CFD analysis.
- The new runner was based on state-of-the-art technology, with double buckets, better cavitation characteristics and higher efficiencies.
- The runner was designed to operate to maximum head range of 325 m.
Model Design and Model Test
The model was designed and manufactured at FLOVEL´s Design Centre and Manufacturing Plant. 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.
Entire model was transported to Vattenfall Hydraulic Laboratory in Sweden.
The model assembly was completed at early in October 2016.
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 test was made for wicket gate torque. The tests were performed during the period 15/10/2016 to 22/12/2016. The final Customer (KSEB) attended the witnessed part of the model test performed on 01-02/12/2016. 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 SHOLAYAR HPP, 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 at both non cavitating and cavitating conditions.
- 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.
- Customer finally accepted the model test results and approved for further manufacturing of the prototype turbine.
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).