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Description of the research subjects
The Department of Hydraulic Machinery, established on the 1st March 2007, continues
research works formerly conducted in the Department of Hydraulic Turbo machinery Tests
and Diagnostics and partly in the Department of Cavitation and Hydraulic Machinery Design,
which were in organization structure of The Centre for Mechanics of Liquids until the end of
February 2007 year. At the present moment Department currying out fundamental and applied
research works in the areas of design, operation and diagnostic tests of hydraulic
turbomachinery as well as modelling unsteady liquid flows in closed conduit and around
bodies.
Development of numerical methods for analysis and design of flow systems of hydraulic
turbines and impeller pumps, investigation on mathematical description of phenomena and
unsteady processes in hydraulic machines flow systems and improvement in the technique of
flow rate measurements in hydrotechnical and hydropower machines and devices are
comprise research subjects cultivated in the Department for longer time. These subjects are
essential for hydropower engineering and especially for small hydropower plants (SHP)
which are renewable energy sources. So far untapped hydropower potential of polish rivers
relates in great fraction to the low heads. In order to rationally take the advantage of possessed
potential it is necessary to develop relatively high efficient and inexpensive hydraulic turbines
constructions. Trying to face the needs of SHP in the Department there is an aspiration to
work up an special construction of small hydraulic turbines appropriate for low and ultra low
heads which would be characterized by high energy efficiency and very low production cost.
This study will be based on modern technique and methodology including three dimensional
computations of the liquid flow through turbine blade systems. Until now, collected were
abundant practical skills in designing small hydraulic turbines and comprehensive experience
of analyzing two dimensional flow through their blade systems, as a basis for new design
methods, moreover earlier began works on three dimensional flow analysis are intensively
developed .
It is planning to develop own original software for three-dimensional flow modelling by
means of vortex singularities method multiple validated in ship propellers applications. In
order to better understand phenomena appearing in liquid flow and to confirm reliability of
developed computer programs the Departments’s laboratory rigs will be exploited which
could be specially modernized and build up within bounds of possibility.
Primary purpose of research works concerning transient phenomena in flow systems of
hydraulic turbines and impeller pumps is improvement and development of numerical
methods for prediction the course of these phenomena. Practical importance of elaborated
methods is related to counteraction unfavorable conditions as excessive pressure changes
produced by water hammer effect or induced by vortex shedding under resonance conditions
severe increase in vibration amplitude of flown past elements. Such phenomena reduce
working life and operational reliability of elements of fluid-flow hydraulic systems and often
pose a serious threat of substantial failures. As especially dangerous situations taking place
in hydraulic pipeline systems should be consider cases when transient pressure decrease
results in appearance of cavitation zones, which are regions of liquid stream discontinuity.
Such situations can occur during quick opening/closing of valves or starting/stopping the
impeller of pumps or hydraulic turbines,
when as a consequence of wave processes produced by water hammer in the closed conduits
pressure at some section drops below its critical value, close to liquid evaporation pressure of
at a given temperature. Cavitation zones which appear during this process die away after some
time. Usually there are multiple emergence and disappearance of these zones. The
phenomena occurring under this conditions – i.e. transient cavitation or liquid column
separation – are almost always accompanying by rapid pressure changes which are reasons for
a large number of failures and occasionally total damages to the elements of the hydraulic
system. Avoidance or partial reduction of such changes could in crucial manner influence
upon increase augmentation of working life and operational reliability of flow systems
elements. Current knowledge concerning predictability of these phenomena is still
unsatisfactory therefore require further investigations.
In its activity the Department holds a wide collaboration with industry. For the most part they
are the companies from the hydropower sector for which various research works and practical
engineering applications are made. These works encompass efficiency tests of hydraulic
turbines and impeller pumps using advanced measurements techniques, design of small
hydraulic turbines, investigations and evaluation of dynamic state of hydraulic units with
determinations theirs durability and working life, as well as technical expert opinions for
hydropower industry and other areas of the economy related to the problems of ascertainment
of causes of breakdowns and failures, preparation of devices and equipment for continuous
flow rate measurement in hydraulic turbines, preparation of laboratory rigs for investigation
on water power phenomena for outer partners.
The whole selection of research topics continued by the Department stem primarily from the
thorough diagnose and current needs of the waterpower engineering. Its topicality is
confirmed by considerable number of direct contracts with hydropower plants to research and
service works, and also large number of technical consultancies and expert opinions which
were given to investors and users of small hydro power units and for the others interested in
the development of hydro-energetic power industry in Poland. Advanced in theoretical
research works and collected experience enable to undertake more and more complicated
tasks set by domestic and foreign customers.
Research activity of the Department is perfectly placed in current polish and european
scientific and economic trends.
The offers list of research works and expert technical opinions for industry:
CONCEPTS OF INSTALLATION AND DESIGNS OF SMALL HYDRAULIC TURBINES,
IMPELLER PUMPS IN TURBINE REGIME
Example 1: The concept of small hydraulic turbine with propeller runner at siphon
installation - the Jaracz Hydropower Plant
Example2: Machine for energy recuperation in industrial installations
Pressure-reducing valve Installation conduit
T
Turbine Main valve
Zawór główny By-pass valve Valves coupling
Schematic diagram of impeller pump application, to run in reverse as turbine, in order
to energy recuperation which is losing in industry installation -- energy is wasted at
pressure-reducing valve as a consequence of throttling of the flow.
1510
1521
1526
n=1532
1515
n=1505
0.00
0.25
0.50
0.75
1.00
1.25
1.50
1.75
2.00
2.25
2.50
0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0
Q t/Q p [-]
,
Ht/
Hp [-
]
sprawność
spad H t /Hp
Optymalne parametry pompy
przy n = 1500 obr/min:
H p = 16 m sł. wody
Qp = 0.056 m3/s
Operation characteristics of pump 150 PJM 250 in turbine regime
TECHNICAL STATE ASSESSMENTS, TECHNOLOGIES
Examples:
Evaluation of technical state of flow systems of hydraulic turbines
Extension of working life of flow systems of hydraulic turbines and impeller pumps,
for instance by reinforcement the most strained constructional elements of such
systems
Evaluation of strength and working life of derivation pipelines supplying hydraulic
turbines
Evaluation of vibration state of rotating systems of hydraulic units
0.5 20.5 40.5 60.4 80.4 100.4 120.3 140.3 160.3 180.2 200.2 MPa
Case without additional reinforcement. Reduced stress (according to Huber-Mises hypothesis) in
shell of turbine branching – outer side, pressure load 415 kPa (for linear-elastic material).
0.308 11.68 23.05 34.41 45.78 57.15 68.52 79.89 91.26 102.6 114.0 MPa
Reduced stress (according to Huber-Mises hypothesis ) in shell of turbine branching no. 1
fortified with a fin (for linear-elastic material).
Strengthening fin at pipeline branching
INVESTIGATION OF POWER PROPERTIES (EFFICIENCY MEASUREMENTS) AND
DYNAMIC STATE OF HYDRAULIC UNITS IN HYDROPOWER PLANTS
Examples:
Field guaranty and acceptance tests (efficiency measurements) of hydraulic
turbines
Efficiency measurements of hydraulic turbines
Commissioning tests of hydraulic units after construction, modernization or
overhaul
Dynamic state tests of hydraulic units – measurements and evaluation of vibration
level in constructional elements, noise level and pressure pulsation under various
operation conditions
74
76
78
80
82
84
86
88
90
92
94
30 40 50 60 70 80 90
eff
icie
ncy o
f tu
rbin
e
[%]
turbine no. 1 (nonmodernized)
turbine no. 2 (modernized)
90
110
130
150
170
190
210
230
30 40 50 60 70 80 90 Pm [MW]
dis
ch
arg
e
[m3/s
]
turbine no. 2 (modernized)
turbine no.1 (nonmodernized)
Power characteristic of hydraulic turbines determined for one effective head on the
basis of test conducted using Gibson method
OPERATION INVESTIGATIONS OF PUMPI NG SETS -- EFFICIENCY AND FLOW RATE
MEASUREMENTS
pump systems and pumping stations of cooling water in conventional and
heatpower plants
preheated water pumps in heatpower plants
flow systems on marine ships
10
12
14
16
18
20
22
5000 7000 9000 11000 13000 Q [m 3 /h]
Hp
[m]
total head as a function of discharge
0.5
0.6
0.7
0.8
0.9
5000 7000 9000 11000 13000
Q [m 3 /h]
[-]
pump efficieny as a function of discharge
Operation characteristics of network water pump determined in one of the heatpower
plant (ultrasonic method of flow rate measurement)
TECHNICAL EXPERT OPINIONS
Determination of breakdown and failure causes of hydraulic machinery and devices
(cavitation failure, damages caused by destructive effect of water hammer, resonant
phenomena, and others).
Examples:
determine the causes of excessive hydraulic unit shaft vibration
determine the causes of shaft cracking of impeller pumps
recognize the causes of penstock rupture
recognize the causes of cracking of cut-off valves housing in various hydraulic flow
systems
control and calibration of ultrasonic flowmeters installed in derivation pipelines of
hydropower plants and other hydrotechnical objects
Disrupted penstock in the Łapino Hydropower Plant
Main scope of works :
In order to evaluate the technical state of the penstock after the failure and to determine the
causes of its burst, the case was subject to an extensive investigation, covering among others:
- non-destructive tests of the preserved penstock shell with a particular focus on the weld
joints,
- material tests of the broken penstock shell,
- analysis of the stress in the shell of the broken penstock section,
- analysis of hydraulic transients under conditions of failure,
- elaboration of guidelines for repair of the penstock and further operation of the power plant.
FLOW RATE MEASUREMENTS IN HYDROPOWER PLANTS
Examples:
preparation and application of the water hammer method (Gibson method) for flow
rate measurement in flow systems of hydraulic turbines and pump-turbines
development, fitting up and starting up the devices for continuous water flow rate
measurement in hydraulic turbines (Winter-Kennedy method and ultrasonic method)
Example of water hammer method (Gibson method ) application
Schematic diagram of supply system of turbines under investigation with marked
hydrometric sections using (which were used) in Gibson method
Localization of pressure taps at each pipeline section 1-1 and 2-2.
60º
10 m
Section 1-1 and 2-2
Manifold
Pressure tap
>3D 2D 2D
1-1 2-2
turbine no. 1
turbine no. 2
tower
reservoir butterfly
valvezawór
motylowy
Waterproof housing with pressure difference transducer installed inside.
Recorded and calculated time changes of values related to flow discharge measurement by
means of Gibson method
0
20
40
60
80
100
80 90 100 110 120 130 140
Y [
%]
Y - recorded wicket gate
opening
-4
0
4
8
12
16
80 90 100 110 120 130 140
Dp
1-2
, Dp
f [k
Pa
]
Dp f - calculated pressure
drop caused by friction in
penstock between sections
1-1 and 2-2
Dp1-2 - pressure difference
measured between penstock
sections 1-1 and 2-2
0
30
60
90
120
150
180
210
80 90 100 110 120 130 140
time t [s]
Q [
m3/s
]
Q - flow rate calculated
according Gibson method
venting valve
from manifold
in section 2-2
from manifold
in section 1-1
pipe with signal
cable inside
COMPUTATIONS OF WATER HAMMER PHENOMENA IN FLOW SYSTEMS OF
HYDRAULIC TURBOMACHERY
Examples:
optimisation of the wicket gate closing procedure in order to protect supply
pipeline form the excessive pressure increase, and turbine generator from the
excessive rotational speed increase,
analysis of various methods of the water hammer effects (mitigation or
attenuation) in order to choice the most advantageous technical solution,
reduction of the excessive pressure pulsation produced by water hummer in fluid-
flow system of pumps and turbines,
control of transient states of hydraulic machines in order to counteract the
unfavorable effects of water hammer.
Exemplary analysis of by-pass valve application in order to diminish water
hammer level
Supply pipeline
Draft tube By-pass valve
Zawór upustowy
Hydraulic turbine
Cut-off valve
odcinający
Down
rservoir
Upper
reservoir
Schematic diagram of by-pass valve application in hydraulic turbine system
1.2
1.3
1.4
1.5
1.6
1.7
0.00 0.05 0.10 0.15 0.20 0.25
D u [m]
pm
ax/p
0,
nm
ax/n
n [-
]
T k = 9 s T k = 15
s
T k = 7 s
p max /p o
n max /n n
without zamyknia wicket gates
closing
Maximum pressure in pipeline (pmax) and maximum rotational speed (nmax) versus by-pass valve
diameter Du for various closing times of wicket gates Tk
CONSTRUCTION OF LABORATORY RIGS Example:
Small size laboratory test rig for studying hydraulic transient in pipe systems with
measurement equipment.
Schematic diagram of laboratory rig for water hammer phenomena
investigation
1. Water-air reservoir, 2. Long pipeline winded up on the reel, 3. Quick closing valve,
4. Control valve, 5. Static pressure transducers, 6. Manometer or pressure gage
transducer with display unit, 7. Electromagnetic flowmeter.
1
6
2
7
5
4
5
4
Partially view of laboratory rig for investigation on pressure wave
propagation in closed conduit
2 – measurement pipeline (copper), 3 – steel reel, 4 – C-shape bar to fasten pipeline,
5 – supports of measurement pipeline, 6 – cutoff valve (ball valve), 7 – spring drive
of cut-off valve, 8 – control valve, 9 – pressure transducer, 10 – turbine flowmeter,
11– potentiometric transducer to record closing of cut-off valve.
2
3
4
5
6
5
7
5
1
1
5
8
5
1
0
9