ISSN:
2181-3906
2023
International scientific journal
«MODERN SCIENCE АND RESEARCH»
VOLUME 2 / ISSUE 5 / UIF:8.2 / MODERNSCIENCE.UZ
1276
APPLICATION OF DIGITAL TECHNOLOGIES IN PROCESS RESEARCH AND
DESIGN OF FLOW PARTS OF STEAM TURBINES
R.K.Kenesbaev
I.G.Kudenov
R.V. Bardashev
https://doi.org/10.5281/zenodo.7982542
Abstract.
The paper highlights the main application of digital technologies in the study of
processes in the design of the flow parts of steam turbines. Reviews of studies in this area have
been carried out. The use of digital technologies for design and production significantly reduces
the time required to introduce new technical solutions when upgrading existing equipment with
long service life, as well as to create promising competitive designs of new generation steam
turbines.
Key words:
digital technology, steam turbines, turbine unit, flow path, power, gas turbine.
ПРИМЕНЕНИЕ ЦИФРОВЫХ ТЕХНОЛОГИЙ В ТЕХНОЛОГИЧЕСКИХ
ИССЛЕДОВАНИЯХ И ПРОЕКТИРОВАНИИ ПРОТОЧНЫХ ЧАСТЕЙ ПАРОВЫХ
ТУРБИН
Аннотация.
В работе освещены основные области применения цифровых
технологий при исследовании процессов проектирования проточных частей паровых
турбин. Проведены обзоры исследований в этой области. Использование цифровых
технологий для проектирования и производства значительно сокращает сроки внедрения
новых технических решений при модернизации существующего оборудования с
длительным сроком службы, а также для создания перспективных конкурентоспособных
конструкций паровых турбин нового поколения.
Ключевые слова:
цифровая технология, паровые турбины, турбоагрегат,
проточная часть, мощность, газовая турбина.
The use of digital technologies for design and production significantly reduces the time
required to introduce new technical solutions for the modernization of existing equipment with a
long service life, and also creates promising competitive designs for the next generation of steam
turbines [1- 6]. The results of calculation and experimental studies carried out at NRU MPEI show
that it is possible to increase the power of the turbine unit by 8-10% due to the improvement of the
aerodynamic properties of parts and aggregates of flow paths. in the initial state of the flow path.
In addition, necessary work can be done at power plants during scheduled maintenance companies.
The maximum total increase in power can be obtained by upgrading the following elements
of the flow path:
* scapular apparatus;
* over-shroud, diaphragm, end seals;
* systems for removal and destruction of coarse moisture;
* designs of valves, branch pipes, steam pipelines.
Figure 1 shows the interface of the program for automated profiling based on Bezier
polynomials of turbomachine lattices, developed at the NRU MPEI at the Department of Steam
and Gas Turbines.
ISSN:
2181-3906
2023
International scientific journal
«MODERN SCIENCE АND RESEARCH»
VOLUME 2 / ISSUE 5 / UIF:8.2 / MODERNSCIENCE.UZ
1277
The use of similar methods in the "manual mode" for the re-profiling of the first three
stages of the medium-pressure cylinder of an 800 MW turbine made it possible to increase the
efficiency of the compartment by 2.4%.
The increase in efficiency was achieved by changing and smoothing the values of the
curvature of the contours of the profiles of the nozzle and working gratings, minimizing the length
of sections flown around with a positive pressure gradient, and forming an optimal change in the
velocity gradient along the streamlined surface.
A promising method for profiling nozzle arrays is the use of a variable angle of flow exit
to redistribute the flow rate along the height of the array. By reducing the exit angle of the flow
near the meridional contours, the flow rate through sections with maximum end losses is reduced,
and, consequently, power losses are reduced. Increasing the outlet angle of the flow in the middle
part of the profile - the core of the flow - leads to an increase in the flow rate in the part of the grid
with minimal losses. As a result, at constant values of the total flow, the useful power of the stage
increases. Calculations show that up to2.0% increase in the power of the stage is achieved due to
the application of the profiling method under consideration.
Figure 1. Interface of the automated profiling program
A significant reduction in stage losses is also possible by reducing steam leakage through
the seals. The average calculated values of the increase in power due to the reduction of losses
from leaks are:
– in the high pressure cylinder ~0.8%; – in the medium pressure cylinder ~ 0.6%; – in the
low pressure cylinder ~ 1.4%.
At the MPEI pilot plant, together with the Department of Steam and Gas Turbines, models
were developed and manufactured for testing seals of a new design - "cellular" seals (Fig. 2), an
analogue of those widely used both for modernization and in new conditions structures of steam
turbines with honeycomb seals.
The results of the tests performed showed good results, confirming the competitiveness of
the proposed technical solution. Significantly reduced the cost of manufacturing seals; the values
ISSN:
2181-3906
2023
International scientific journal
«MODERN SCIENCE АND RESEARCH»
VOLUME 2 / ISSUE 5 / UIF:8.2 / MODERNSCIENCE.UZ
1278
of leakage of the working fluid and the level of aerodynamic exciting forces do not exceed the
values characteristic of honeycomb seals.
Figure 2. Models of "cellular" seals
The results of the experiments showed the possibility of using honeycomb, cellular seals
for moisture separation in the last stages of the low-pressure cylinder of TPP turbines and in the
flow parts of NPP steam turbines. To carry out comprehensive research, characteristics and
improvement of seal designs, a special stand has been developed that allows testing different types
of seal models both in air and in steam with different humidity values (Fig. 3)
Fig 3. Stand for testing models of seals
The use of digital technologies in testing elements of the flow parts of steam turbines
significantly expands the possibilities of studying gas-dynamic, thermal thermodynamic
processes, which creates a reliable basis for verifying the results of calculations and switching
from using standard computer systems, for example, ANSYS to homemade codes.
By home code, we mean calculation programs debugged on the basis of experimental data
and tests of elements of flow parts.
The development of such codes is fundamentally important for the application of
calculation methods in the design of almost all elements of the flow path. Comparison of
ISSN:
2181-3906
2023
International scientific journal
«MODERN SCIENCE АND RESEARCH»
VOLUME 2 / ISSUE 5 / UIF:8.2 / MODERNSCIENCE.UZ
1279
calculation results and experimental results shows that "standard" programs can have significant
errors and unacceptably large discrepancies when compared with the results of full-scale tests and
experiments.
As a rule, the maximum deviations were recorded in areas of the flow path that are
significant for the occurrence of aerodynamic forces and losses, and, therefore, fundamentally
important from the point of view of the reliability of the results obtained. The main problems in
carrying out calculations arise in channels with limiting values of a positive pressure gradient for
continuous flow, transonic flow velocities, developed zones of flow separation, and high values of
humidity.
In the zone of phase transitions at transonic and supersonic flow velocities, there is an
intense interaction of shock waves and condensation with non-stationary changes in flow
parameters and the appearance of additional dynamic forces on the elements of the flow path.
Inadmissibly large errors in modeling processes in wet steam in some cases led to accidents
on operating equipment. There is a case when, justified by calculations, changes in the angle of
installation of the working blade of the last stage of a turbine with a power of 300 MW, operating
in wet steam, by only three degrees, led to the occurrence of self-oscillations with the destruction
of the blade apparatus.
Comparison of the results of calculations for "problem" options with the data obtained on
model and full-scale experimental stands, followed by changes in the calculation programs, makes
it possible to develop "home" codes necessary for the application of sound technical solutions in
the design of equipment.
The use of digital technologies has significantly expanded the possibilities of studying
thermophysical processes in the flow parts of turbomachines. The Moscow Power Engineering
Institute (NRU MPEI) has an excellent base for testing and aerodynamic debugging of steam
turbine equipment: the MPEI training and experimental CHPP.Figure 4 shows a thermal diagram
of one of the stands for studying the elements of the flow parts of steam and gas turbines. A feature
of the thermal scheme of the stand is the ability to control and select the parameters of the working
fluid not only at the flow inlet, but also at the outlet of the model under study, which allows you
to independently change the Mach numbers and Reynolds numbers during experiments.
ISSN:
2181-3906
2023
International scientific journal
«MODERN SCIENCE АND RESEARCH»
VOLUME 2 / ISSUE 5 / UIF:8.2 / MODERNSCIENCE.UZ
1280
Fig. 4. Thermal scheme of the stand for studying the elements of the flow parts of
steam and gas turbines
In the thermal scheme, a developed system for preparing the working fluid is made, which
provides superheated, saturated or wet steam with specified parameters at the entrance to the model
under study. Depending on the problem being solved, the flow velocity can vary over a wide range
from subsonic to supersonic values. In conclusion, we formulate the main directions of promising
developments using digital technologies in the aerodynamics of the flow parts of steam turbines.
Development of home codes for 3D design of the blade apparatus, taking into account the
peculiarities of the movement of the liquid phase. Reducing aerodynamic energy losses and
increasing the reliability of elements of the flow parts of turbines: steam intake systems, seals,
transition and exhaust pipes.
Experimental study of new designs of the exhaust compartment with increased throughput.
Development of standard designs of the exhaust compartment for powerful steam turbines with
rotor blades limit length. The exhaust compartment consists of the last two stages and a diffuser
exhaust pipe. The final stage of development is testing on a full-scale test bench of the plant.
Development and application of effective methods for reducing the dispersion of the wet steam
flow, as well as improving systems for separating moisture from the flow path of a steam turbine.
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