Development of turbines with improved erosion performance Research collaboration between industry and university

NORAD regarding financial support for construction of TTL. A total sum of 1.3 million US was needed for the construction of the lab, of which NORAD funded 60, Nepalese industries and institutes supported this endeavor and contributed 20, whereas remaining 20 was contributed by KU itself. The lab was designed by faculties of KU with support from Norwegian University of Science and Technology NTNU. NTNU has a similar lab called Waterpower Laboratory, which was established in 1917 and was refurbished and modernized in 2001. Hence, their guidance from the initial design phase of TTL was found to be very useful. After the inauguration on November 10, 2011, TTL has been able to carry out several activities within the lab to maintain the dynamicity at high exhilaration. In the course of time, TTL has perceived an ambitious target of becoming a center of excellence for turbine design, manufacturing and testing facilities in Nepal. This paper presents the past and ongoing activities conducted by the lab together with future endeavors to achieve this long term goal. There are various aspects from which the current situation can be observed, this includes development of the lab capacity, motivation of applied research for bridging the gap between industry and university and improving the socio-economic status of the people through employment opportunities. This paper describes each of these individual aspects in the form of three models that TTL is implementing. Some of the fields described in these models are completed, whereas some of the fields are in the stage of development. 2. Turbine Testing Lab – Facilities and Activities Located at the foothill of Kathmandu University at Dhulikhel, Nepal, the lab operates within the academic environment of the university and collaborates with the industries and private sectors to address technical and societal aspects of hydropower development and turbine-related issues.TTL is the only lab in the world which can perform tests with 30 m natural head. The location and topography of KU has provided the opportunity to place an upper reservoir so as to create a 30 m natural head. The lab has two centrifugal pumps each of 250 kW with variable frequency drive VFD for each pump. Each pump canproduce maximum flow of 0.25 m 3 s and maximum head of 75 m. The pumps can be connected in series and parallel combination producing a maximum head of 150 m and maximum flow of 0.5 m 3 s respectively. TTL has the capacity to perform prototype test up to 300 kW turbines and perform model test for larger turbines. The lab has provision to have four test rigs at a time, along with notches and water volume measurement arrangements for calibration of measuring instruments. Over past few years, the lab has developed and enhanced the competences in performing computational simulations to strengthen the research capacity. It has also acquired state-of-art technologies such as Rapid Prototyping Machine, a 3D printer to produce complicated turbine component models with high accuracy, Particle Image Velocimetry PIV setup to study the flow phenomena in turbines, metallurgy microscopes for studying the turbine materials and sediment particles, Rotating Disc Apparatus RDA to carry out erosion testing and Borescope as a non-destructive testing for investigating defects or imperfections in inner parts of turbine. Following are some of the achievements of TTL since its establishment.

a. Development of turbines with improved erosion performance

The conventional Francis turbines in the context of Nepal are not performing satisfactorily in erosive environment. Several research works have been carried out in KU and TTL, most of them in collaboration with NTNU to reduce the erosion in turbine parts by improving the design. It has been computationally tested that the optimization of hydraulic design of blade profile alone can reduce sediment erosion in Francis runners up to 30[6]. TTL has also designed and developed a 92 kW Francis model of Jhimruk HP 4 MW, with the conventional and optimized runners to test in the lab. This turbine accounts as the first Francis turbine that was designed and manufactured in Nepal, with the design of TTL and manufactured by one of the 27 manufacturers of Nepal Nepal Hydro Electric NHE Pvt. Ltd.. TTL was funded by RenewableNepal program in a project from 2010- 2013, entitled ‘Development of Francis turbines with new Design philosophy addressing the problems of sediment erosion for a sustainable hydropower developm ent in Nepal’, in the course of which, these achievements were made. Another project was funded by NORAD from 2012-2013, in parallel to the above project, entitled ‘Feasibility study for turbine manufacturing and testing facility in Nepal by identifying th e erosion potential of sediments in major basins of Nepal’. a b c Figure 1: a Design of Francis turbine runner blades from computational analysis[7] b Manufacturing of the 92 kW Francis turbine at NHE c Installed test rig of the turbine at TTL

b. Research collaboration between industry and university

TTL gives preference to projects having industrial andor university collaboration. As shown in Figure 1 b, the project of Renewable Nepal conducted by TTL had NHE as the manufacturing industrial partner. This project also had NTNU, Norway as the expert partner. In 2011-2013, TTL hosted a MS by Research student funded by Himal Power Ltd. to carry out study of failure analysis due to root cracks in Pelton turbines of Khimti HP. In 2014, TTL also assisted a PhD student from University of Calgary, Canada to conduct experimental and numerical study on a 15 kW cross-flow turbine available at TTL. Every year, there is a research collaboration between NTNU and KU, where students from NTNU spends some time at TTL to carry out studies which are relevant to Nepal. Some of the students of KU are even funded by NTNU and KMOU Korea Maritime and Ocean University for higher studies in their universities. Besides, TTL is also supporting undergraduate students from Sikkim and Tribhuwan University, Nepal to carry out different projects. In 2014, TTL has also carried out design works of a bifurcation with hydraulic and mechanical integrity for DaraundiKhola HP project. a b c Figure 2: a MS by Research on failure analysis of Pelton runner for Khimti HP [8] b Design of IEC standard Francis and Pelton test rigs at TTL from Master students of NTNU c Design and computational analysis of a bifurcation for DaraundiKhola HP

c. Leading the research activities into next level