At the beginning of 2010 for the first time in Iran, Farab Equipment Manufacturing Company started to design and supply turbines and inlet valves for Azad hydro power plant project. The 10,000 KW Azad project has three horizontal Francis hydro units each with a capacity of 3,500 KW. The turbine net head is 95.0 meters, each unit turbine discharge is 4.0 meter cubic per second, and the rated turbine speed is designed to be 1,000 rpm. The best model turbine hydraulically designed by Farab Equipment Manufacturing Company was model tested in November 2010 at the laboratory of Turboinstitut in Ljubljana, Slovenia. It had a very good performance and high efficient hydraulic results.
The mechanical/detail designs of turbine components comprising over 350 manufacturing drawings, documents, calculation books and manufacturing procedures have been designed and prepared by Farab Equipment Manufacturing Company in-house. The fabrication of turbine parts were distributed among different local manufacturers and currently, power house is commissioned successfully in December 2015.
Another example that shows Farab’s ability in the area of designing hydro turbines is the Gotvand small hydropower plant turbine. general specifications of this project are as follows:
- Plant output: 10.4 MW (2*5.200 KW)
- Turbine type: Horizontal Francis
- Turbine rated output: 5.200 KW
- Turbine maximum output: 5.700 KW
- Rated head: 125 m
- Maximum head: 145 m
- Rated discharge: 4.6 m3/s
- Rated speed: 600 rpm
Design of the small turbine in this power plant empowered Farab in the area of small water turbines. This resulted in Farab expanding its work to the design of micro and pico turbines as well as designing test rigs for micro and pico Francis and Pelton turbines, which are used in the process of verification of turbines.
Several activities needed to be performed in the design and report preparation processes some of the most important steps done in this regards are as follows:
- Blade shape design for better hydraulic behavior, blade shapes from another Farab verified model were chosen and developed in this turbine.
- Hydraulic design: using another model, loads which will be applied on turbine parts due to water flow were defined.
- Detail design and 3D modeling: a 3D model of the whole turbine was made for facilitation of manufacture, layout verification of the whole system, and usage in stress-strength analysis.
- Stress-strength analysis: using the forces found in the CFD step, strength of different parts of turbines are then calculated via FEM software. This step is also useful for verification of the loads found by analytical methods.
- Analytical calculation: calculation of all forces on the turbine, required force for servomotor of distributors, transient flow calculation, foundation load, etc. were done in this stage. Water hammer calculation was performed using SIMSEN software developed by the EPFL University.
- Tolerance design and drawings: generating general drawings with BOM, shop drawings with manufacturing tolerances, and selecting proper materials are the next step.
- Preparation of required procedures: different procedures need to be prepared for the purpose of design, transportation, installation, operation and commissioning. For example, hydraulic test procedure, installation procedure, heat treatment procedure, balancing procedure, etc. are some of these procedures that need to be prepared by a technical team.
Aiming to become independent of other companies in the verification process, Farab was first intrigued by experience in the area of designing Francis turbines to start designing a test rig for micro and pico Francis turbines, and then became interested in Pelton turbines afterwards. In a nutshell, model testing is done by first changing input parameters of a smaller model similar to the test model, then measuring and calculating other independent and dependent variables, and finally verifying turbine operation. Results are then shown in different forms such as dimensionless parameters, various tables, curves, and figures. This can be summarized in these steps:
- Identification of operation of turbine- measuring and calculation of working and output variables.
- Illustration of data in various charts, tables and diagrams- preparation of Hill Chart
- Preparation of model test report
- Preparation of the videos and pictures of the process