Analysis of Physical Processes in the Flow Parts of Gas Turbines with Different Blade Chords

2021 ◽  
pp. 40-53
Author(s):  
V.D. Molyakov ◽  
B.A. Kunikeev ◽  
N.I. Troitskiy
Keyword(s):  
Flow Structure ◽  
Gas Turbines ◽  
Relative Elongation ◽  
Experimental Studies ◽  
Flow Path ◽  
Rotor Blades ◽  
Turbine Stage ◽  
Physical Processes ◽  
Integral Characteristics ◽  
Flow Part

Theoretical and experimental studies of the current flowing in the lattices of the turbine stage impeller with a change in the elongation of its blades at constant constraining diameters of the flow part (constant blade lengths) are carried out. Four single-stage turbines with different chords of rotor blades and their relative elongations have been investigated. To explain the nature of the integral characteristics of the turbine stage with a change in the relative elongation of the rotor blades, detailed studies of the spatial flow structure in the gap between wheels and behind the impeller were carried out. The peculiarity of the operation of four impellers in the turbine stage is shown when the geometry of the channels changes along the height of the flow path - from active at the root to highly reactive at the periphery. A characteristic redistribution of the local values of the efficiency and losses along the height of the lattices associated with a change in the elongation of the rotor blades and the rotation of the lattices has been revealed. It was found that with a decrease in the elongation of the rotor blades, the zone with the minimum efficiency moves from the root sections to the peripheral ones with its simultaneous restructuring and an increase in the minimum efficiency in this zone. In this case, the integral values of the efficiency of impellers with different relative elongations of the blades remain the same and sufficiently high.

The Effect of Tip Shroud Geometries on Last Turbine Stage Efficiency

2018 ◽  
Author(s):  
Andrey Granovskiy ◽  
Igor Afanasiev
Keyword(s):  
Flow Structure ◽  
Radial Distribution ◽  
Gas Turbines ◽  
Rotor Blades ◽  
Loss Reduction ◽  
Steam Turbines ◽  
Turbine Stage ◽  
Last Stage ◽  
Partial Shroud ◽  
Stage Efficiency

Last stages of steam turbines and heavy-duty power gas turbines contribute significantly to output power and efficiency of whole turbine. Moreover, radial distribution of parameters downstream of the last stage provides boundary conditions for diffuser design. Thus, the increase of the last stage efficiency and obtainment of favorable radial distribution downstream of the last rotor blade is very important. Due to the long blades of last stages, resonance might occur. To avoid dangerous frequencies a damping wire or damping bolts are used. Such damping elements result in additional losses, so to minimize these losses a damping shroud is used instead. In general, the full damping shroud has to provide both the aerodynamic loss reduction and the resonance frequency offset. However, in most cases due to mechanical integrity limits instead of the full shroud a partial shroud is used. In this case the loss reduction feature of the partial shroud is diminished as compared with the full shroud. Sometimes, the use of the partial shroud results in the decrease of the efficiency compared with a stage with unshrouded rotor blades at small tip clearances. In this paper, a numerical investigation of the flow structure around full and partial shrouds with various geometries as well as the effect of the various shroud geometries on the turbine stage efficiency is carried out. Eight geometries with different number of fins of various heights are studied. Moreover, stage efficiencies for both shrouded and unshrouded blade are compared. Based on this comparison, reasonable design recommendations aimed to reduce the losses within the radial gap over the shroud are developed. In particular, filling the space in the gap with the additional honeycombs is considered and the effect on the flow structure and the last stage efficiency investigated. Numerical results obtained in the paper correspond well to the published test data.

Numerical Modelling of Fluid-Structure Interaction in a Turbine Stage for 3D Viscous Flow in Nominal and Off- Design Regimes

2010 ◽  
Author(s):  
Romuald Rzadkowski ◽  
Vitaly Gnesin ◽  
Lubov Kolodyazhnaya
Keyword(s):  
Boundary Layer ◽  
Viscous Flow ◽  
Gas Turbines ◽  
Element Model ◽  
Boundary Layer Separation ◽  
Rotor Blades ◽  
Navier Stokes ◽  
Turbine Stage ◽  
Flow Distortion ◽  
Boundary Layer Interaction

In recent years there have been major developments in turbomachinery aeroelasticity methods. There are now greater possibilities to predict blade vibrations arising from self-excitation or inlet flow distortion. This is not only important with regard to aircraft compressor and fan blade rows, but also in the case of the last stages of steam and gas turbines working in highly loaded off-design conditions. In order to predict the unsteady pressure loads and aeroelastic behaviour of blades (including the computation of shock waves, shock/boundary layer interaction and boundary layer separation), complete Reynolds-averaged Navier-Stokes (RANS) equations are used in modelling complex and off-design cases of turbomachinery flows. In this paper the 3D RANS solver, including a modified Baldwin and Lomax algebraic eddy viscous turbulence model, is presented to calculate unsteady viscous flow through the turbine stage, while taking into account the blade oscillations but without the separating of outer excitation and unsteady effects caused by blade motion. The numerical method uses the second order by time and coordinates an explicit finite-volume Godunov’s type difference scheme and a moving H-O structured grid. The structure analysis uses the modal approach and a 3D finite element model of blade. To validate the numerical viscous code, the numerical calculation results were compared with the 11th Standard Configuration measurements. Presented here are the numerical analysis results for the aeroelastic behaviour of a steam turbine last stage with 760 mm rotor blades in a nominal and an off-design regime.

Experimental Studies on Aerodynamic Performance and Unsteady Flow Behaviors of a Single Turbine Stage With Variable Rotor-Stator Axial Gap: Comparisons With Time-Accurate Numerical Simulation

2007 ◽  
Author(s):  
Ken-Ichi Funazaki ◽  
Kazutoyo Yamada ◽  
Mamoru Kikuchi ◽  
Hideaki Sato
Keyword(s):  
Experimental Studies ◽  
Three Dimensional ◽  
Aerodynamic Characteristics ◽  
Aerodynamic Performance ◽  
Rotor Blades ◽  
Turbine Stage ◽  
Flow Angle ◽  
Count Ratio ◽  
Stator Vane ◽  
Flow Information

This paper describes experimental results from detailed measurements of aerodynamic performance of a single stage in the turbine test rig of Iwate University, focusing on effects of the rotor-stator axial gap in the turbine stage. The measurements using a 5-hole Pitot tube provide time-averaged flow information such as stagnation pressure distributions and velocity vectors behind the stator as well as the rotor. Time-accurate three-dimensional flow analyses are also made in this study using an in-house N-S code. Realistic flow analyses are achieved in terms of blade-count ratio only by adding one stator vane, resulting in 3:4 blade-count ratio for the present simulation. Aerodynamic characteristics at the exits of the stator as well as the rotor for three axial gap cases are examined in detail through the experimental data and the numerical results. It follows that the increase in the axial gap gives rise to small increment in exit flow angle from the stator, seemingly affecting the flow structure near the hub as well as tip regions around the rotor blades. Furthermore, the turbine stage efficiency slightly decreases with the axial gap enlargement.

scholarly journals Economy increase of turboset flow unit

2015 ◽  
Vol 2015 (4) ◽  
pp. 38-44
Author(s):  
Александр Осипов ◽  
Aleksandr Osipov ◽  
Алексей Дроконов ◽  
Aleksey Drokonov ◽  
Андрей Волженцов ◽  
...  
Keyword(s):  
Gas Turbines ◽  
Turbine Rotor ◽  
Middle Part ◽  
The Body ◽  
Rotor Blades ◽  
Honeycomb Seal ◽  
Heat Leakage ◽  
Flow Part ◽  
Definition Of ◽  
Activity Decrease

At present time a considerable part of installed facilities of steam – and gasturbine units exhausted the body resources in connection with that their modernization is an urgent problem. The effectiveness increase in the work of a flow part in turbine units can be achieved at the expense of peripheral leakage decrease in bandless and banded stages of steam and gas turbines. In banded stages it can be achieved due to the choice of optimum value in the peripheral overlap of turbine rotor blades. In the BSTU there was obtained a dependence allowing the approximate definition of the optimum value for the overlap. At the same time the design of peripheral honeycomb seal with variable geometry allowing the operation with increased gaps in vibrating dangerous modes (start and stop) and in nominal conditions – with reduced gaps that gives the decrease of operation heat leakage about 30% in comparison with a basic design is offered. For bandless stages on the outer outline of an impeller the spiral profile groove manufacturing is of-fered for the effect of flow blocking at periphery. In the BSTU on the test air benches it was established that at the optimum angle of spiral profile groove slope equal to 150 to the plane of the impeller rotation the efficiency increment for the stage of an average fanning is equal to about 1% in comparison with the variant of a smooth overlap. For the purpose of stage operation reliability increase at economy conservation there is offered a creation of the hollow chamber with 2…3mm depth in the middle part of the blade exterior cross section. The application of variants developed for the flow part modernization in turbomachines should contribute to effectiveness and reliability increase of powergenerating units and ensure the ecological characteristics improvement in plants at the expense of their vibro-acoustic activity decrease.

scholarly journals The effect of deformation of flow part of elastomeric elements of self-acting valves on characteristics of low-speed long-stroke compressor stages

2021 ◽  
Vol 5 (4) ◽  
pp. 33-38
Author(s):  
I. S. Busarov ◽  
◽  
S. S. Busarov ◽  
V. L. Yusha ◽  
◽  
...  
Keyword(s):  
Experimental Studies ◽  
Flow Section ◽  
Variable Cross ◽  
Cross Sectional ◽  
Low Speed ◽  
Experimental Stand ◽  
Integral Characteristics ◽  
Flow Part ◽  
Long Stroke ◽  
Feed Coefficient

The results of the study of the influence of changes in the area of the flow section in the seat of selfacting valves with elastomeric elements on the characteristics of low-speed compressor stages are presented. A method of experimental research of low-speed compressor stages with the possibility of obtaining instantaneous parameters of the gas state in the working chamber of the stage and its integral characteristics and an experimental stand for its implementation have been developed. The results of comparative experimental studies have confirmed the effectiveness of the valve design with a variable cross-sectional area of the seat in comparison with known designs — an increase in the feed coefficient and isothermal indicator efficiency is at least 10...15%.

Numerical investigation of non-uniform flow in twin-silo combustors and impact on axial turbine stage performance

2021 ◽  
pp. 095765092199394
Author(s):  
Hafiz M Hassan ◽  
Adeel Javed ◽  
Asif H Khoja ◽  
Majid Ali ◽  
Muhammad B Sajid
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Internal Flow ◽  
Large Temperature ◽  
Clear Understanding ◽  
Gas Temperature ◽  
Turbine Stage ◽  
Flow Angle ◽  
Axial Turbine ◽  
Stage Performance

A clear understanding of the flow characteristics in the older generation of industrial gas turbines operating with silo combustors is important for potential upgrades. Non-uniformities in the form of circumferential and radial variations in internal flow properties can have a significant impact on the gas turbine stage performance and durability. This paper presents a comprehensive study of the underlying internal flow features involved in the advent of non-uniformities from twin-silo combustors and their propagation through a single axial turbine stage of the Siemens v94.2 industrial gas turbine. Results indicate the formation of strong vortical structures alongside large temperature, pressure, velocity, and flow angle deviations that are mostly located in the top and bottom sections of the turbine stage caused by the excessive flow turning in the upstream tandem silo combustors. A favorable validation of the simulated exhaust gas temperature (EGT) profile is also achieved via comparison with the measured data. A drop in isentropic efficiency and power output equivalent to 2.28% points and 2.1 MW, respectively is observed at baseload compared to an ideal straight hot gas path reference case. Furthermore, the analysis of internal flow topography identifies the underperforming turbine blading due to the upstream non-uniformities. The findings not only have implications for the turbine aerothermodynamic design, but also the combustor layout from a repowering perspective.

Influence of Leading Edge Fillet and Nonaxisymmetric Contoured Endwall on Turbine NGV Exit Flow Structure and Interactions With the Rim Seal Flow

2013 ◽  
Author(s):  
Özhan H. Turgut ◽  
Cengiz Camcı
Keyword(s):  
Flow Structure ◽  
Total Pressure ◽  
Guide Vane ◽  
Axial Flow ◽  
Leading Edge ◽  
Turbine Rotor ◽  
Rotor Blades ◽  
Constant Thickness ◽  
Computational Evaluation ◽  
Nozzle Guide

Three different ways are employed in the present paper to reduce the secondary flow related total pressure loss. These are nonaxisymmetric endwall contouring, leading edge (LE) fillet, and the combination of these two approaches. Experimental investigation and computational simulations are applied for the performance assessments. The experiments are carried out in the Axial Flow Turbine Research Facility (AFTRF) having a diameter of 91.66cm. The NGV exit flow structure was examined under the influence of a 29 bladed high pressure turbine rotor assembly operating at 1300 rpm. For the experimental measurement comparison, a reference Flat Insert endwall is installed in the nozzle guide vane (NGV) passage. It has a constant thickness with a cylindrical surface and is manufactured by a stereolithography (SLA) method. Four different LE fillets are designed, and they are attached to both cylindrical Flat Insert and the contoured endwall. Total pressure measurements are taken at rotor inlet plane with Kiel probe. The probe traversing is completed with one vane pitch and from 8% to 38% span. For one of the designs, area averaged loss is reduced by 15.06%. The simulation estimated this reduction as 7.11%. Computational evaluation is performed with the rotating domain and the rim seal flow between the NGV and the rotor blades. The most effective design reduced the mass averaged loss by 1.28% over the whole passage at the NGV exit.

Predicting Flameholding for Hydrogen and Natural Gas Flames at Gas Turbine Premixer Conditions

2016 ◽  
Vol 138 (12) ◽  
Author(s):  
Elliot Sullivan-Lewis ◽  
Vincent McDonell
Keyword(s):  
Power Generation ◽  
Natural Gas ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Experimental Studies ◽  
Temperature Variations ◽  
Auto Ignition ◽  
Chamber Temperature ◽  
Transient Events ◽  
Significant Effort

Lean-premixed gas turbines are now common devices for low emissions stationary power generation. By creating a homogeneous mixture of fuel and air upstream of the combustion chamber, temperature variations are reduced within the combustor, which reduces emissions of nitrogen oxides. However, by premixing fuel and air, a potentially flammable mixture is established in a part of the engine not designed to contain a flame. If the flame propagates upstream from the combustor (flashback), significant engine damage can result. While significant effort has been put into developing flashback resistant combustors, these combustors are only capable of preventing flashback during steady operation of the engine. Transient events (e.g., auto-ignition within the premixer and pressure spikes during ignition) can trigger flashback that cannot be prevented with even the best combustor design. In these cases, preventing engine damage requires designing premixers that will not allow a flame to be sustained. Experimental studies were conducted to determine under what conditions premixed flames of hydrogen and natural gas can be anchored in a simulated gas turbine premixer. Tests have been conducted at pressures up to 9 atm, temperatures up to 750 K, and freestream velocities between 20 and 100 m/s. Flames were anchored in the wakes of features typical of premixer passageways, including cylinders, steps, and airfoils. The results of this study have been used to develop an engineering tool that predicts under what conditions a flame will anchor, and can be used for development of flame anchoring resistant gas turbine premixers.

Calculation of Technical Characteristics of the Technical Fleet Vessels Involved in Ensuring Safety of the Offshore Facilities of Oil and Gas Complex

2021 ◽  
pp. 7-13
Author(s):  
S.V. Matsenko ◽  
◽  
V.M. Minko ◽  
A.A. Koshelev ◽  
V.Yu. Piven ◽  
...  
Keyword(s):  
Oil And Gas ◽  
Oil Pollution ◽  
Raw Materials ◽  
Experimental Studies ◽  
Industrial Safety ◽  
Theoretical Studies ◽  
Physical Processes ◽  
Oil Spill Response ◽  
Sea Area

Violation of industrial safety rules during the operation of offshore facilities for the production, storage and transportation of the hydrocarbon raw materials leads in the most cases to pollution of the marine environment with oil and its components. The works on localization and elimination of such pollution are carried out with the help of vessels of the technical support fleet and booms. When developing oil spill response plans at such facilities, a calculated determination of the technical characteristics of vessels and booms is required that are sufficient to carry out the planned activities. The basic design principles for determining the towing capacity of the technical fleet vessels involved in the localization and elimination of oil and oil product spills by trawling methods are given in the article. The calculation is based on theoretical studies performed by the authors of the physical processes occurring during the movement of objects of a mobile trawling order in the sea area. The results obtained during the course of theoretical studies were confirmed by the experimental studies carried out by the authors personally using the real pieces of equipment in the actual development of tasks for training spill containment by trawling. As a result, the empirical dependencies were obtained and experimentally confirmed, which can be used to calculate technical characteristics of the ships as part of the mobile orders and anchor systems as part of stationary orders intended for the localization and elimination of oil pollution. These results can be used, among other things, for the calculated substantiation of the technical characteristics of the technical fleet vessels designed to ensure safety of the offshore facilities for production, storage, and transportation of the hydrocarbon raw materials.

Ingestion Into the Upstream Wheelspace of an Axial Turbine Stage

1994 ◽  
Vol 116 (2) ◽  
pp. 327-332 ◽  
Author(s):  
T. Green ◽  
A. B. Turner
Keyword(s):  
Pressure Distribution ◽  
Static Pressure ◽  
Three Dimensional ◽  
Computer Code ◽  
Rotor Blades ◽  
Rotor Speed ◽  
Turbine Stage ◽  
Flow Rates ◽  
Static Pressure Distribution ◽  
Axial Clearance

The upstream wheelspace of an axial air turbine stage complete with nozzle guide vanes (NGVs) and rotor blades (430 mm mean diameter) has been tested with the objective of examining the combined effect of NGVs and rotor blades on the level of mainstream ingestion for different seal flow rates. A simple axial clearance seal was used with the rotor spun up to 6650 rpm by drawing air through it from atmospheric pressure with a large centrifugal compressor. The effect of rotational speed was examined for several constant mainstream flow rates by controlling the rotor speed with an air brake. The circumferential variation in hub static pressure was measured at the trailing edge of the NGVs upstream of the seal gap and was found to affect ingestion significantly. The hub static pressure distribution on the rotor blade leading edges was rotor speed dependent and could not be measured in the experiments. The Denton three-dimensional C.F.D. computer code was used to predict the smoothed time-dependent pressure field for the rotor together with the pressure distribution downstream of the NGVs. The level and distribution of mainstream ingestion, and thus the seal effectiveness, was determined from nitrous oxide gas concentration measurements and related to static pressure measurements made throughout the wheelspace. With the axial clearance rim seal close to the rotor the presence of the blades had a complex effect. Rotor blades in connection with NGVs were found to reduce mainstream ingestion seal flow rates significantly, but a small level of ingestion existed even for very high levels of seal flow rate.

Sign in / Sign up

Export Citation Format

Share Document