EXPERIENCES OF R&D OF HYDRAULIC TURBINES … · EXPERIENCES OF R&D OF HYDRAULIC TURBINES AT KATHMANDU UNIVERSITY ... which endure huge economic losses. ... The circuit has 5.5 kW

EXPERIENCES OF R&D OF HYDRAULIC TURBINES AT KATHMANDU

UNIVERSITY

Biraj Singh Thapa1*

, Krishna Prasad Shrestha1, Bhola Thapa

1

1Department of Mechanical Engineering, Kathmandu University, Nepal

*Corrensponding author: Tel.: +977-9842137934; fax: + 977-11-661443

E-mail address: [email protected]

ABSTRACT

Demand of clean energy has increased opportunities of hydropower development globally.

Basins under Himalayas are considered of much likely for hydro electricity generation. The feasible

hydropower potential in Nepal alone is 43,000 MW, out of which only less than 700 MW has been

harnessed till the date. It is apparent that Nepal holds the future market for hydropower

developments. In 2010 AD, the Government of Nepal has also announced its intentions to develop

38,000 MW of hydropower in next 25 years. Prefeasibility studies have shown that more than 70%

of sites in Nepal would need Francis type of turbine for the power generation.

Hydropower plants in Nepal and in the entire region across Himalaya have a specific problem of

turbine wear. Presence of hard particles, in a large amount, in almost all the rivers across this region

causes the hydro turbine parts to erode. The major effects of the erosion are reduction in efficiency

and shortening life of the turbines, which endure huge economic losses. Future of sustainable

hydropower business in this region would be largely influenced by the effective solution to this age

long problem of turbine erosion.

Kathmandu University (KU) is one of the leading educational institutes in Nepal with the high

standards of academic excellence. KU has a decade long experience with R&D of micro-hydro

turbines. KU have also conducted several studies related to sediment erosion in hydro turbine

materials. With the primary focus to find the solution to the problem of sediment erosion in Francis

turbine, KU has recently established a Turbine Testing Lab (TTL) in compliance with the

international standards. TTL is equipped with the facilities for the purpose of academic and

professional research in hydro turbines and is expected to be the research center of new turbine

manufacturing industry to be established in the country.

This paper summaries the opportunities and the challenges of hydropower developments in

Nepal. The history of activities and the associated achievements in R&D of hydro turbine and

sediment erosion at KU will also be briefed. Success of a collaborative research with a

manufacturing industry to find the solution for erosion of ring in Francis runner will also be

presented. Features of TTL and scope of its utilization will also be discussed. Beside these, the

progress of the ambitious project at TTL on design optimization of Francis turbine for effective

reduction in sediment erosion will also be elaborated.

KEYWORDS

Sediment erosion, Francis turbine, CFD, Design optimization

1. INTRODUCTION

There is a huge potential of new hydropower power developments across the basins of

Himalaya and Alps of Andes. Nepal, a small south Asian country, alone has more than 40,000 MW

of feasible hydropower potential still to be harnessed [1]. In 2010, Government of Nepal has

announced its intentions with some policies to develop 38,000 MW hydropower in next 25 years [2].

There have been several socio-economic and political challenges in Nepal, which limited the

construction of new power plants in the country. Besides these challenges Nepal and the region

faces a specific problem of sediment erosion in the run-off-river power plants (PP). Almost all the

river and rivulets in the Himalayan region contains 60% - 80% of particles in its sediments having

hardness number above 6 in Moh’s scale [3]. Presence of hard particles causes the turbine parts to

erode, which eventually reduces the efficiency and life of the turbine causing economic losses. Fig.

1 shows the effects of sediment erosion in Hydro turbines operating in Himalayan basins.

Several research activities have been done to quantify and minimize the effects of sediment

erosion in hydraulic turbines [7-9]. Financial feasibility of future hydropower developments across

Asian basins would be largely influenced by technological advancements. New innovations to

prevent erosion of mechanical equipment exposed to sediments are important needs at the present.

Kathmandu University (KU) is an autonomous, not-for-profit, non - government institution

dedicated to maintain high standards of academic excellence. Since its establishment in 1990, KU

has been working for the prominent solution for sediment erosion in hydro turbines. Several

technical research conducted at KU have helped the hydropower developers to improve the

efficiency in power plants. KU has been collaborating with national and international experts and

institutions for improving its research standard.

2. ACHIEVEMENTS OF MINIATURE LABORATORIES

KU has been putting its effort into development of hydro turbines for Nepalese context.

Research for hydro turbines at KU started with two miniature turbine laboratories named as Pico

Turbine Laboratory and Waterpower Laboratory.

The Pico Turbine Laboratory is dedicated for research and development of axial flow Pico

propeller turbines. It has successfully designed and tested low-cost 800 W Pico set having 90%

overall efficiency (Fig. 2a). Now it is developing a similar 1.5 kW set, amenable to mass-production

at low cost [10].

The Waterpower Laboratory was dedicated for design and performance analysis of Pelton and

Francis turbines and also provided professional trainings. This laboratory was also used for research

on issues related to sand erosion of turbine components. Five different Pelton bucket profiles

designed at KU and manufactured locally were tested for impact and flow visualization (Fig. 2b)

[11]. Francis turbine for 130 kW micro hydro projects (Fig. 2c) is under development phase at KU.

Both miniatures laboratory are still in operation and are mostly utilized for students’ laboratory

and academic research activities.

3. ACHIEVEMENTS FROM RESEARCH ON SEDIMENT EROSION

KU has a unique experience with understanding the nature of sediment erosion in hydraulic

turbines. Several numerical and experimental studies have been conducted to classify and quantify

the erosion.

3.1. Understanding Erosion Potential Of Sediments In Himalayan Basins

A simple hydraulic circuit as shown in Fig. 3 was used to investigate the effect of river sand

flowing with water on turbine blade material. The circuit has 5.5 kW mono-block centrifugal pump

(Head 45 m and Q 6 l/sec). Valves control the flow of water and particles. Bypass circuit is used to

control the flow of water through nozzle. Vertical hopper of height 1.05 m, ahead of nozzle is filled

with known weight of sand and closed from top. Once the pump is started and valve of hopper is

opened, water creates turbulence inside the hopper and sands fall down in the horizontal pipe,

which is then accelerated by the water and strike the specimen just outside the nozzle. The velocity

of the jet is computed by measuring the discharge. The jet strikes the specimen in free air, hence this

system could be considered to be similar to Pelton turbine system.

Sediment samples are collected from several locations covering streambeds of some of the

Nepalese rivers of different river basins. Mineralogical analysis of samples was done to identify

quartz content and their shape in each river. The erosion tests were carried out on turbine material

16Cr5Ni Martensitic Stainless steel by 1 kg sand samples. The erosion rate obtained from the

laboratory erosion test in same operating condition with different sand samples between 425-300,

300-212 and less than 212 μm are averaged and presented in figure 4 along with the corresponding

quartz contents in the sample [3].

3.2. Investigation Of HVOF Coatings For Erosion Resistance

Rotating Disc Apparatus (RDA) was developed at Kathmandu University to study the sand

erosion, cavitation and their combined effect. It consists of a rotating disc with four cavitation

inducers and driven by a 7.5 kW motor at 2880 rpm. The motion of submerged body can be

simulated up to 39 m/s velocity. Test objective was to compare performance of HVOF coatings with

stainless steel. This provided an opportunity for accelerated sand erosion testing for a comparison of

different materials. The disc is made up of Stainless Steel SS316 and only half of this disc was

coated with tungsten carbide (86% Co 10% Cr 4%). The erosion damage in stainless steel and

HVOF coating were compared and analyzed based on the area and pattern of erosion [12]. Fig. 5

shows the test specimen with HVOF coating and Fig. 6 shows the erosion pattern generated by

combined effects of sediment erosion and cavitation.

4. USE OF MODERN COMPUTATIONAL TOOLS

KU has also been able to use the numerical tools and computational software for R&D of

hydraulic turbines. Two important field of study employing the computational tools for R&D of

hydraulic turbines at KU are characterization of sediment particles, and design optimization of

Francis turbine to minimize effects of sediment erosion.

4.1. Characterization Of Sediment Particles

An image processing program has been developed on MATLAB 6.5 platform to extract the

exact shape of sand particles collected. Sand particles were collected from the erosion sensitive

power plants and its digital images had been acquired. These shapes have further been analyzed by

artificial neural network. This network has been first trained for the known input and known output.

After that it is trained for unknown input and known output. Finally these networks could recognize

any shape given to it and gives the shape which is nearest to the seven predefined shape [13]. Fig.

7-9 shows the image processing steps used to characterize the sediment particles and Fig. 10 shows

percentage of sediment particles with different predefined shapes in one the hydropower plants in

Nepal.

5. PROGRESS OF DESIGN OPTIMIZATION OF FRANCIS RUNNER FOR SEDIMENT

HANDLING

Hydropower projects in Nepal and the region have been facing the severe problem of turbine

erosion due to sediment particles. Geographic conditions in Nepal makes high head Francis turbine

a better choice. However, Francis turbines are found to be more sensitive to the effects of sediment

erosion [14]. KU in close cooperation with NTNU has started a unique project for Design

optimization of Francis runners for sediment handling. Developing results have shown the

possibilities to reduce sediment erosion in Francis runner significantly by optimizing the hydraulic

design alone.

Erosion in hydro turbines is a complex phenomenon, which depends upon several parameters.

Design of Francis turbines is unique to each site and hence takes time and effort to produce the best

design for specific conditions. This makes design optimization of Francis turbines for erosive

environment a challenging task. One of the emerging solutions to prevent the erosion in Francis

turbines is to reduce the relative velocity inside the runner by improving hydraulic design. For this

it is important to evaluate relation of the turbine design parameters on sediment erosion so as to

identify those parameters that can be attuned to reduce the erosion. Recent advancements in

computing tools and software have added advantage to these studies.

A new program ‘Khoj’ has been developed to create and optimize the design of Francis runner.

‘Khoj’ is also featured to compare erosion in runner blades for different design cases. The final

design can be exported to CFD and CAD tools for further analysis. Parametric survey was carried

out with ‘Khoj’ to evaluate the relative effect of each design parameter on sediment erosion. The

results from ‘Khoj’ were compared to that from CFD analysis to estimate effects of the design

variables on hydraulic performance. Several optimized designs were developed and analyzed to

fulfill the desired condition of erosion and efficiency.

5.1. Reference Design

Jhimruk Hydroelectric Center (JHC) in Nepal is considered as the reference case for this study.

JHC is a typical power plant suffering from sediment erosion of high head Francis turbine in South

Asia. It has three units of splitter blade Francis runners of 4.2 MW each. With the basic design data

presented in Table 1 and values of hydraulic design parameters presented in Table 2, a reference

design to suit this site is created. Full blade runner has been considered as the reference design

instead of splitter blade due to limitation of the design program. The erosion factor for the

reference design is 1.

5.2. Design Optimization Range And Methodology

The hydraulic design parameters are varied within a defined range and its effects on erosion factor

is evaluated. Table 2 lists the range of variation of the design parameters considered for this study.

For evaluating effects of sediment erosions in optimized designs, the following two terms are

defined as the indicators and the means of comparison of relative erosion in the Francis turbine

runner.

Erosion Tendency (Et)

It is quantification of tendency of a specific design of runner to be eroded in similar sediment

conditions. Erosion tendency is defined as follows:

[m3/s

3] (1)

Where n is the number of segment area (Ai) in the runner blade surface. Wi is the relative

velocity of flow in each segment area. The segment area is the area between the intersection of

stream lines and stream points in the runner blade surface.

Erosion Factor (Ef)

It is ratio of erosion tendency of each new design with respect to the reference design. Erosion

factor is defined as follows:

[-] (2)

The erosion factor estimates a quantitative difference in sediment erosion of runner with the

change in hydraulic design alone. In this study the erosion factor is used as a means to compare the

relative erosion in the optimized designs of runner with respect to the reference design.

5.3. CFD Analysis Parameters

To verify the reference design, a CFD simulation is carried out. Jhimruk Hydroelectric Center,

Nepal has been taken as the reference case. Designs from Matlab are exported to Ansys CFX-13.

Simulations are done to evaluate the hydraulic performance and erosion on blade surface. Exactly

same process has been repeated to all the Design Analysis to maintain consistency. Comparisons of

results are done with that from Matlab for the same designs. Table 3-6 presents the parameters

selected for the CFD analysis. Fig. 11 and Fig. 12 shows the ATM mesh generated by TurboGrid

and Fig. 13 shows the computational domain for CFD processing.

CFD analysis of reference runner has been done to evaluate the hydraulic parameters and sediment

erosion in runner blade surface as reference value to compare the same for the optimized designs.

Fig. 13 shows the pressure distribution on the pressure side of the blade. It shows smooth transition

of pressure from inlet to outlet section. Fig. 14 shows the relative velocity at the outlet section of the

runner. It shows the average out let velocity at the out let of runner to be in between 30 m/s to 35

m/s. Fig 15 shows sediment erosion rate density on the pressure side of reference runner blade

computed by Ansys CFX-Solver for the parameter presented in table 5 and report generated by the

Ansys CFX-Post for the parameters presented in the table 6. It shows that the erosion pattern to be

spread at the entire outlet section of the runner blade.

5.4. Results of Design Optimization:

Consequences of variation in each design parameter are evaluated from the design program Khoj

and results are compared with that with CFD analysis. Effect of the variation on the erosion factor is

of primary interest. However, the effects on other relevant deign parameters is also observed. It is

found that the runner outlet diameter, peripheral velocity at inlet, and blade angle distribution have

the highest effect on sediment erosion of Francis runner.

The largest reduction of erosion was obtained when increasing the number of pole pairs, which

implies that the rotational speed of the turbine is decreased. This does however increase the size of

both the turbine and the generator, which cause increased investment costs as well. CFD analysis

shows that the hydraulic efficiency for this design is higher than for the reference design.

It was also discovered that by changing the blade angle distribution, and consequently also the

energy distribution, a substantial reduction of erosion was possible without changing the physical

dimensions or the rotational speed of the turbine. The efficiency for this design is also higher than

for the reference design.

The most promising design was found as a combination of these two effects, giving a reduction

of the erosion of 50 percent compared to the reference design. CFD analysis for this design show a

good efficiency and acceptable flow conditions in the runner. Strength analyses of the blade would

be beneficial, but have not been performed under this study.

The results of the study from Khoj propose some modifications in standard design to reduce the

sediment erosion. However, each modification has some limitations that have to be considered

during the design optimization. Table 7 presents the modifications required in standard design of

Francis runner along with limitations for each modification. Results of this study can be utilized to

develop better Francis turbines to handle sediments.

6. TURBINE TESTING LAB AT KATHMANDU UNIVERSITY

A new Turbine Testing Laboratory (TTL) has been constructed at KU with financial assistance

from Norway. It aims to deliver its facilities to local and international developers and consultants.

The lab have two pumps each with specification 160 kW, 75 m head and 0.25 m3/sec flow rate to re-

circulate water. It has piping system connecting lower and upper reservoir to circulate water to run

turbine. Two pumps can be operated in series and parallel circuits to obtain different operational

regime and this can test up to 300 kW turbines. Fig 16 presents the schematic layout of new TTL at

KU.

In recent future the lab will be equipped with state of the art control system with

electromagnetic flow meters, pressure transducers and sensors. Internationally recognized

certification endorsed by International Electrotechnical Commission (IEC-60193) will be

maintained at TTL for model tests. The technical support for the laboratory will be provided by

Waterpower Laboratory, NTNU which has experience of turbine testing for almost 100 years. In

coming years, TTL intends to include state of the art technologies such as Computational Fluid

Dynamics (CFD), Finite Element Method (FEM) analysis for new design or upgrading existing

turbines, innovative design of hydro-mechanical components for power plants, and specialized

trainings to engineers and technicians. Table 8 presents the objectives of the turbines testing lab at

KU.

6.1. Current Utilization Of TTL

Strategic planning for long term use of TTL is underway. However, TTL is already active in

several areas of Hydropower development some of them are as follows:

Combined R&D activities with RenewableNepal support

RenewableNepal is a research program leading to business development funded by NORAD

and managed by KU in cooperation with SINTEF Energy Research, Norway.

This support is making Nepal more independent and self-reliant in utilizing its own huge

hydropower resources as well as other renewable energy resources. Under the RenewableNepal

Program, TTL has been granted sum of 5.7 million NRs. to initiate combined R&D works for

design of hydro turbines to resist sediment erosion. KU and NTNU as Nepalese and Norwegian

research institutes, and NHE and DynaVec as Nepalese and Norwegian manufacturing industries,

have formed a project consortium with the following objectives:

1. Develop a new design philosophy for Francis turbine to minimize losses due to sediment

erosion by technology transfer and innovation.

2. Create a Center of Excellence at TTL for research and development of hydraulic turbines as a

foundation for a new turbine manufacturer in Nepal.

3. Prepare technical background and understanding between local and international institutions and

industries for establishing a new turbine manufacturer in Nepal.

The project has duration of three years, with start date of August 2010. This project is aimed to

transfer the Norwegian turbines R&D competency of Norwegian research institute to Nepalese

research institute and Norwegian expertise in manufacturing of turbines to Nepalese manufacturer.

The ultimate goal is the holistic and long-term sustainable development of hydropower business in

Nepal.

Design improvements of turbines for micro/ mini hydropower projects:

KU waterpower laboratory will be incorporated under TTL with following activities:

a. Further improvements of Pelton buckets: Improvements of Pelton buckets are on the R&D

stage. It is expected to reach to manufacturer after second stage of optimization as a result from

past research. Target has been set for runners up to 500 kW with efficiency of 85%.

b. Test verification and improvements of Francis runner: The modified 130 kW Francis runner is

under development process. The test would be done at new TTL facility. The results will be

evaluated and optimization will be done for its commercial use. The design of the runner for the

projects up to 1 MW by local manufacturing has been expected to match subsidy policy of

government of Nepal up to 1 MW.

c. Pump-as-turbine for micro hydro projects: Nepalese Micro-Hydropower plants are suffering

from low plant efficiency particularly due to poorly designed and manufactured turbines.

Possibilities of use of pumps as turbines have been attempted at several sites in other developing

countries. New thread of research has been initiated at TTL to optimize impeller of centrifugal

pump to be used as generating unit in micro-hydro projects.

d. Analysis of root crack of Pelton runner: 12 MW Pelton runner of Khimti power plant with

cracks at the roots of buckets with the depth up to 120mm has been sent to KU for investigation.

The runner is at TTL and is under investigation to find the cause of crack and suggest the

probable solutions to prevent similar events in future.

e. Data bank and Technical support:

Apart from the R&D works, TTL has also been commencing other relevant activities, which

will directly or indirectly support hydropower development in the country and in region. This

includes:

i. Data bank of design and performance of Hydro-Mechanical and Electro-Mechanical

equipments of major Hydropower projects in Nepal.

ii. Data bank of feasibility study and design requirements for upcoming projects.

iii. Provide professional consultancy services for design and test certification of turbine and

associated parts.

iv. Provide relevant short term courses and training programs to industrial staffs and

professionals.

7. CONCLUSIONS:

Nepal has huge prospects and opportunity in hydropower developments. Several new projects

are being constructed and more are under planning phase. Hydropower plants in Nepal and the

entire region have been facing a specific challenge of sediment erosion of turbine components.

Several studies and research are being conducted to find the feasible solution to this age long

problem.

Since its establishment, Kathmandu University has prioritized research activities for

hydropower development in Nepal. Major efforts have been given for understanding the nature of

sediment erosion in hydro turbines and optimizing existing designs of Francis turbines for

minimizing effects of sediment erosion. During its decade long R&D activities, KU has been able to

develop its own laboratory facilities and utilize the computational tools together with experimental

studies.

Recently KU has established a new turbine testing lab with state of art research facilities to

render services as per international standards. It is expected that the lab will act as the center of

excellence for R&D of hydraulic turbines by initiating innovative research in close cooperation with

local and international hydropower developers and research institutes.

8. REFERENCES

[1] Ghimire, H.K., Small Hydro Development Opportunities and Present Status in Nepal, Proc

Int Conf - Hydro SriLanka 2007.

[2] Thapa, B. S., Thapa, B., Dahlhaug, O. G., Center of Excellence at Kathmandu University

For R&D and Test Certification of Hydraulic Turbine, Proc. Int. Conf. on Hydraulic

Efficiency Measurement 2010; India.

[3] Thapa, B., Shrestha, R., Dhakal, P., Thapa, B. S., Problems of Nepalese Hydropower

Projects due to Suspended Sediments, J. Aquatic Ecosystem Health and Management 2005;

251-258.

[4] Pradhan, P. M. S, Dahlhaug, O. G, Joshi, P. N., Støle, H., Sediment and Efficiency

Measurements at Jhimruk Hydropower Plant – Monsoon, Technical report from Hydro Lab

2004.

[5] Thapa B., “Sand Erosion in Hydraulic Machinery”, Doctoral thesis at NTNU; 2004.

[6] Sharma, H. K., Power generation in sediment laden rivers, Int. J. of Hydropower & Dams

2010; Issue 6, 112-116.

[7] Padhy, R. P. Saini, A Review on silt erosion in hydro turbines, Renewable and Sustainable

Energy Reviews 1974–1987 2008.

[8] Dahlhaug, O. G., Skåre P. E., Mossing V., Gutierrez A., Sediment resistive Francis

runner at Cahua Power Plant, Int. J. Hydropower and Dams 2010; Issue 2, 109-112.

[9] Neopane H.P., Dhalhaug O. G., Thapa B., Alternative Design of a Francis Turbine for Sand

Laden Water, Int. Conf. on Hydropower- Hydro Sri Lanka 2007.

[10] Cannell, J. K., Pokhrel, R., Bhandari, B., Testing and development of Pico Hydro Turbines,

Int. J. of Hydropower & Dams 2005; 12: 3.

[11] KC. B., Thapa B., Pressure distribution at inner surface of selected Pelton bucket for micro

hydro, Kathmandu University J. Science, Engineering and Technology 2009; Vol. 5, No. II,

42-50.

[12] Thapa B., P. Upadhyay, O. G. Dahlhaug, M. Timsina, R. Basnet, HVOF coatings for

erosion resistance of hydraulic turbines: Experience of Kaligandaki-A Hydropower Plant,

Water Resources and Renewable Energy Development in Asia 2005; Vietnam.

[13] Shrestha, B. P., Suman, S. K., Shape feature extraction and pattern recognition of sand

particles and their impact, Proc. SPIE Int. Soc. Opt. Eng. 2005; 5996, 59960X.

[14] Brekke, H., Discussion of Pelton turbine versus Francis turbines for high head turbines,

IAHR, Colorado, 1978.

(a) (b) (c) (d)

Fig. 1 Francis Turbines performing under basins of Himayala: Damage in runner at

Jhimruk PP after one year of operation [4]. (b) Surface erosion Pelton runner at Khimti

PP [5]. (c,d) Damage to guide vanes and cheek plates at Nathpa PP [6].

(a) (b) (c) Fig. 2 Research at the miniature turbine laboratory at Kathmandu University: (a)

800 W Propeller Turbine designed and tested at Pico turbine test laboratory [10], (b)

Flow visualization in Pelton bucket at water power laboratory [11] (c) 130 kW

Francis turbine ready for performance test

Quartz content and Erosion rate

01020304050607080

West seti

Jhum

ruk

Rapti K

hola

Madi R

ever

Ganaha

Aru

n k

hola

Modi-2

Modi -

1

Aadhi khola

Tin

au

Kule

khani

Chitla

ng

Palu

ng

Bagm

ati

Manahara

Dhobi

Gaur

(R

oshi

Dhad K

hola

Khim

tiK

him

ti k

hola

Tam

akoshi

Phedi

Dola

l G

hat

Sunkoshi

Sapta

koshi

KarnaliWest Rapti GandakiTinauBagmati Bagmati

(Ktm.

Koshi

Rivers (sampling location) and basins

Qu

atr

z c

on

ten

t (%

vo

lum

e)

0,05,010,015,020,025,030,035,0

Ero

sio

n r

ate

mg

/kg

Quartz content

Erosion rate

Fig. 3 Erosion measurement test rig

at KU

Fig. 4 Quartz content from mineralogical analysis

and erosion rate from laboratory erosion test [3]

Fig. 5 Erosion test of

stainless steel and

HVOF coating

Fig. 6 Erosion patter

generated by sand erosion

[12]

Fig. 7 Raw image of sand

particles

Fig. 8

Cropped

image of

single sand

Fig. 9 Edge

boundary of

single sand

Fig. 10 Shape and size distribution

of sediment particles in one of

hydropower plants in Nepal [13]

Fig. 11 TurboGrid ATM mesh Fig. 12 Computational domain

Fig. 13 Pressure distribution in

pressure side of blade

Fig. 14 Relative velocity at

blade outlet

Fig. 15 Sediment erosin on reference

runner blade

Fig. 16 Schematic layout of TTL at KU

Table 1. Basic design data for JHC

S.N. Parameters Symbol Unit Value

1 Net design

head H m 201.5

2

Net

discharge

per unit

Q m3/s 2.35

3 Runner

efficiency n % 96

Table 2. Hydraulic design parameters

S.N. Parameters Symbol Unit

Value for

Reference

design

Range of

optimization

1 Outlet

diameter D2 m 0.54 0.4 - 0.75

2

Number of

pole pairs in

generator

ZP - 3 3 - 12

3

Reduced

peripheral

velocity at

inlet

U1 - 0.74 0.65 - 1

4

Acceleration

of flow

through

runner

Acc % 35 0-50

5 Height of

runner b m 0.16 0.05-0.4

6 Blade angle

distribution β ⁰ linear

4 different

nonlinear

Reaction turbine test rig

Impulse turbine test rig

Pumps and

flow circuit

Reservoir

Callibration

unit

Lower

Upper Reservoir

Table 3 Parameters for CFX-

TurboGrid

Paramater Type value

Grid Node

Count Fine 250000

Reynolds No

500000

Topology

Definition ATM Optimized

Table 4 General Parameters for

CFX-Pre

Paramater Type

Turbulance SST

Flow State Steady

Flow type Inviscid

Erosion

Model Tabakoff

Morphology Particle Transport

fluid

Table 5 Parameters for

CFX-Pre Sediment Data

Data value Unit

Material Quartz

Density 2,65 g/cm3

Diamter 0,1 mm

Shape

factor 1

Flow rate 0,07 kg/s

500 PPM

Table 6 Parameters for CFX-Post Erosion

Analysis

Paramater

Max

value Unit

Sediment

Erosion

rate Density

3,00E-07 kg/m2.s

0,3 mg/m2.s

Table 7. Design modifications for reducing

sediment erosion

S.N. Proposed Modifications Limitations

1 Increase outlet diameter

of runner Size of turbine

2 Increase number of pole

pairs in generator Speed number

3 Reduce peripheral

velocity at inlet Reaction ratio

4 Increase acceleration of

flow through runner

No of runner

blades to prevent

back flow

5 Increase blade height of

runner Fabrication

6 Change shape of blade

angle distribution

Strength,

Fabrication

Table 8 Objectives of Turbine Testing Lab at KU

S.N. Objectives Activities

1

Build

competence and

knowledge in

Nepal and for

South Asia

region

• Teaching/learning facility

• Industrial courses

• Staff training for the

industry

• R&D back-up for

industrial development

2

Build a

laboratory for

hydro turbines

• Certification of mini- and

micro-turbines sold on the

Nepali and the regional

market

• Model testing of turbines

for larger power plants

3 Centre for

research

• Sand erosion research in

turbines

• Turbine and pump

development

• Maintenance of turbines

4

Meeting place

for the industry

and university

• Student projects for the

industry

• Share information and

experience at regional level