Degradation of Aerodynamic Performance of an Intermediate-Pressure Steam Turbine Due to Erosion of Nozzle Guide Vanes and Rotor Blades

Deteriorations of nozzle guide vanes (NGVs) and rotor blades of a steam turbine through a long-time operation usually decrease a thermal efficiency and a power output of the turbine. In this study, influences of blade deformations due to erosion are discussed. Experiments were carried out in order to validate numerical simulations using a commercial software ANSYS-cfx. The numerical results showed acceptable agreements with experimental results. Variation of flow characteristics in the first stage of the intermediate pressure steam turbine is examined using numerical simulations. Geometries of the NGVs and the rotor blades are measured using a 3D scanner during an overhaul. The old NGVs and the rotor blades, which were used in operation, were eroded through the operation. The erosion of the NGVs leaded to increase of the throat area of the nozzle. The numerical results showed that rotor inlet velocity through the old NGVs became smaller and the flow angle of attack to the rotor blade leading edge became smaller. Consequently, the rotor power decreased significantly. Influences of the flow angle of at the rotor inlet were examined by parametric calculations and results showed that the angle of attack was an important parameter to determine the rotor performance. In addition, the influence of the deformation of the rotor blade was examined. The results showed that the degradation of the rotor performance decreased in accordance with the decrease of blade surface area.

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An Impact Assessment of Erosion of Nozzle Guide Vanes and Rotor Blades on Aerodynamic Performance of a Gas Turbine by CFD

Volume 2B: Turbomachinery ◽

10.1115/gt2019-90636 ◽

2019 ◽

Author(s):

Koichi Yonezawa ◽

Masahiro Takayasu ◽

Genki Nakai ◽

Kazuyasu Sugiyama ◽

Katsuhiko Sugita ◽

...

Keyword(s):

Gas Turbine ◽

Gas Turbines ◽

Rotor Blade ◽

Cfd Simulation ◽

Rotor Blades ◽

Total Power ◽

Guide Vanes ◽

Turbine Performance ◽

Nozzle Guide ◽

Nozzle Guide Vanes

Abstract Nozzle guide vanes (NGVs) and rotor blades deteriorate due to erosion, and this may affect the aerodynamic characteristics of gas turbines. According to previous studies, the erosion of first-stage NGVs significantly affected the blade loading of the first-stage rotor. An increase in the tip gap also may significantly affect the gas turbine performance. In the present study, numerical investigations have been carried out using a real eroded nozzle and blade geometries for two purposes. One purpose was to clarify the influences underlying the deterioration of the nozzle and the rotor blade, such as the effects on the erosion of NGVs in the first stage and the effects of the tip gap on the gas turbine performance. The other was to develop a method to estimate the total gas turbine performance using a CFD simulation and a heat balance analysis. The results show that the erosion of NGV leads to an increased flow rate and affects the operating condition of the gas turbine cycle. This, in turn, can decrease the total thermal efficiency. The experimental results suggest that an increase in the tip gap width decreases rotor output almost linearly, and the numerical results showed the same tendency. The influence of the tip gap in the real gas turbine condition was also examined, revealing that an increase in the tip gap leads to an increase in the pressure loss in the nozzle downstream as well as around the rotor blade itself. Consequently, the total power output and the isentropic efficiency of the turbine decreased.

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Study over thermal state of gas turbine engine metal-ceramic rotor blades and nozzle guide vanes under thermal shock and thermal-cyclic loading conditions

Journal of Thermal Science ◽

10.1007/s11630-004-0026-3 ◽

2004 ◽

Vol 13 (2) ◽

pp. 163-166

Author(s):

A. V. Soudarev ◽

A. A. Souryaninov ◽

V. Ya. Podgorets ◽

V. V. Grishaev ◽

V.Yu Tikhoplav ◽

...

Keyword(s):

Cyclic Loading ◽

Thermal Shock ◽

Gas Turbine ◽

Thermal State ◽

Rotor Blades ◽

Guide Vanes ◽

Turbine Engine ◽

Metal Ceramic ◽

Nozzle Guide ◽

Nozzle Guide Vanes

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A CFD Approach to Fluid Dynamic Optimum Design of Steam Turbine Stages With Stator and Rotor Blades

Volume 7: Turbomachinery, Parts A, B, and C ◽

10.1115/gt2010-22477 ◽

2010 ◽

Cited By ~ 4

Author(s):

Xin Yuan ◽

Tadashi Tanuma ◽

Xiaofeng Zhu ◽

Zhirong Lin ◽

Daisuke Nomura

Keyword(s):

High Pressure ◽

Steam Turbine ◽

Optimum Design ◽

Rotor Blade ◽

Fluid Dynamic ◽

Rotor Blades ◽

Turbine Stage ◽

Tip Leakage ◽

Pressure Steam ◽

End Wall

An advanced aerodynamic design optimization system for steam turbine stages considering rotor blade tip leakage and blade end-wall non-axis-symmetric contouring has been developed. Using this system, fluid dynamic optimizations were carried out for a steam turbine stage with stator and rotor blades. The system includes parametric modeling of blade and end-wall contouring, evaluation system with in-house or package CFD software and optimization strategy module. The designs of rotor blade and hub end-wall surface in a typical large-scale high-pressure steam turbine stage were optimized in order to know this design optimization impact on enhancing the stage efficiency. Results show that: from the current well designed high pressure steam turbine stage, the demonstrated efficiency enhancement with the present optimum design is around 0.2% under consideration of rotor tip leakage. Design cycle could be greatly shortened by parallel optimization algorithm and cluster PC, and especially four days could be sufficient for an optimization with one thousand iterations on 20 CPUs of 2.0G cluster PC.

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Effect of Incidence Angle on Gas Turbine First-Stage Nozzle Guide Vane Leading Edge and Gill Region Film Cooling

Volume 4: Heat Transfer, Parts A and B ◽

10.1115/gt2012-69298 ◽

2012 ◽

Cited By ~ 1

Author(s):

Yang Zhang ◽

Xin Yuan

Keyword(s):

Film Cooling ◽

Incidence Angle ◽

Leading Edge ◽

Inlet Flow ◽

Flow Angle ◽

Cooling Performance ◽

Guide Vanes ◽

Nozzle Guide ◽

Nozzle Guide Vanes ◽

Compound Angle

The nonuniformity of the Hp turbine inlet flow field put forward higher requirements for NGV (Nozzle Guide Vanes) leading edge and gill region film cooling. The assumption of design condition in most of the experiments couldn’t reflect the true operation environment in the Hp turbine NGV. The factor of off-design condition was incorporated into the experiment in this research. The GE-E3 Hp turbine nozzle guide vanes were used in the experiment to investigate the cooling performance of injection from leading edge and gill region with inlet Reynolds numbers of Re = 3.5×105 and inlet Mach number of Ma = 0.1. The compound angle fan-shaped film cooling hole configuration was applied. The cooling characteristics at off-design condition were analyzed and compared in the paper. The leading edge and gill region film cooling performance was assessed with the incidence angle varying from i = −10deg to i = +10deg. The blowing ratio varying from M = 0.7 to M = 1.3, was also selected as an experimental variable. Film cooling effectiveness distribution was measured using PSP (Pressure Sensitive Paint) technique. The film cooling performance of the compound angle fan-shaped holes was assessed at both design and off-design conditions. The object of this research is to change the concept that NGV leading edge film cooling experiment only needs the data at design condition. Through the comparative analysis of experimental results at different inlet flow angle, the influence of off-design condition on NGV leading edge and gill region film cooling could be illustrated at a reasonable level.

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Investigation of Vortex Shedding and Wake-Wake Interaction in a Transonic Turbine Stage Using Laser-Doppler-Velocimetry and Particle-Image-Velocimetry

Journal of Turbomachinery ◽

10.1115/1.2103092 ◽

2005 ◽

Vol 128 (1) ◽

pp. 178-187 ◽

Cited By ~ 23

Author(s):

E. Göttlich ◽

J. Woisetschläger ◽

P. Pieringer ◽

B. Hampel ◽

F. Heitmeir

Keyword(s):

Vortex Shedding ◽

Particle Image ◽

Rotor Blades ◽

Laser Doppler ◽

Turbine Stage ◽

Time Resolved ◽

Guide Vanes ◽

Wake Interaction ◽

Nozzle Guide ◽

Nozzle Guide Vanes

The current paper presents a time-resolved experimental flow investigation in a highly loaded transonic gas turbine stage operating continuously under engine representative conditions. The measurement was performed with a two-component laser-doppler-velocimeter (LDV) and a three-component stereoscopic particle-image-velocimeter (3C-PIV). Unsteady velocity data were obtained in axis perpendicular planes (LDV) and tangential planes (3C-PIV) between stator and rotor as well as downstream of the rotor. The results of the time-resolved investigation at several radii show the vortex shedding process from the trailing edges of nozzle guide vanes and rotor blades. This vortex shedding was found to be phase locked to higher harmonics of the blade passing frequency. Pressure waves evoked by reflection of the trailing edge shocks of the vanes on the passing rotor blades interact with the boundary layers on the rear suction side of the vanes and on the rotor blade surfaces while running upstream and downstream the flow. They are responsible for this phase-locking phenomenon of the shedding vortices. At midspan, the vortices shedding from stator and rotor blades were also observed by PIV. The in-plane vorticity distribution was used to discuss the wake-wake interaction indicating that wake segments from the nozzle guide vanes were chopped by the rotor blades. These chopped segments are still visible in the distributions as a pair of counter rotating vortices. The nozzle wake segments are transported through the rotor passages by the flow, influencing the vortex street of the rotor blades as they pass by with the higher velocity of the main flow. A comparison with a numerical simulation is also given.

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Investigation of Vortex Shedding and Wake-Wake Interaction in a Transonic Turbine Stage Using Laser-Doppler-Velocimetry and Particle-Image-Velocimetry

Volume 6: Turbo Expo 2005, Parts A and B ◽

10.1115/gt2005-68579 ◽

2005 ◽

Cited By ~ 3

Author(s):

E. Go¨ttlich ◽

J. Woisetschla¨ger ◽

P. Pieringer ◽

B. Hampel ◽

F. Heitmeir

Keyword(s):

Vortex Shedding ◽

Particle Image ◽

Rotor Blades ◽

Laser Doppler ◽

Turbine Stage ◽

Time Resolved ◽

Guide Vanes ◽

Wake Interaction ◽

Nozzle Guide ◽

Nozzle Guide Vanes

The current paper presents a time-resolved experimental flow investigation in a highly loaded transonic gas turbine stage operating continuously under engine representative conditions. The measurement was performed with a two-component Laser-Doppler-Velocimeter (LDV) and a three-component stereoscopic Particle-Image-Velocimeter (3C-PIV). Unsteady velocity data were obtained in axis perpendicular planes (LDV) and tangential planes (3C-PIV) between stator and rotor as well as downstream of the rotor. The results of the time-resolved investigation at several radii show the vortex shedding process from the trailing edges of nozzle guide vanes and rotor blades. This vortex shedding was found to be phase locked to higher harmonics of the blade passing frequency. Pressure waves evoked by reflection of the trailing edge shocks of the vanes on the passing rotor blades interact with the boundary layers on the rear suction side of the vanes and on the rotor blade surfaces while running upstream and downstream the flow. They are responsible for this phase-locking phenomenon of the shedding vortices. At midspan, the vortices shedding from stator and rotor blades were also observed by PIV. The in-plane vorticity distribution was used to discuss the wake-wake interaction indicating that wake segments from the nozzle guide vanes were chopped by the rotor blades. These chopped segments are still visible in the distributions as a pair of counter rotating vortices. The nozzle wake segments are transported through the rotor passages by the flow, influencing the vortex street of the rotor blades as they pass by with the higher velocity of the main flow. A comparison with a numerical simulation is also given.

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ANALYSIS OF AVERAGING METHODS FOR NON-UNIFORM TOTAL PRESSURE FIELDS

Journal of Turbomachinery ◽

10.1115/1.4053020 ◽

2021 ◽

pp. 1-23

Author(s):

Daniel Burdett ◽

Thomas Povey

Keyword(s):

Experimental Data ◽

Mach Number ◽

Total Pressure ◽

Rotor Blades ◽

Performance Parameters ◽

Guide Vanes ◽

Component Plane ◽

Exit Mach Number ◽

Nozzle Guide ◽

Nozzle Guide Vanes

Abstract A common objective in the analysis of turbomachinery components (nozzle guide vanes or rotor blades, for example) is to calculate performance parameters, such as total pressure or kinetic energy loss coefficients, from measurements in a non-uniform flow-field. These performance parameters can be represented in a range of ways. For example: line-averages used to compare performance between different radial sections of a 3D component; plane-averages used to assess flow (perhaps loss coefficient) development between different axial planes; and fully mixed-out values used to determine the total loss associated with a component. In this paper, we compare a range of methods for calculating aerodynamic performance parameters including plane-average methods with different weighting schemes and several mixed-out methods. We analyse the sensitivities of the different methods to the axial location of the measurement plane, the radial averaging range, and the exit Mach number. We use high-fidelity experimental data taken in several axial planes downstream of a cascade of engine parts: high pressure (HP) turbine nozzle guide vanes (NGVs) operating at transonic Mach number. The experimental data is complemented by CFD. We discuss the underlying physical mechanisms which give rise to the observed sensitivities. The objective is to provide guidance on the accuracy of each method in a relevant, practical application.

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Numerical Optimization of a Steam Turbine Control Stage by Flowpath Profiling Using Evolutionary Algorithm

Volume 7: Turbomachinery, Parts A, B, and C ◽

10.1115/gt2011-46237 ◽

2011 ◽

Cited By ~ 2

Author(s):

Nils Moser ◽

Rene´ Volkert ◽

Franz Joos

Keyword(s):

Evolutionary Algorithm ◽

Steam Turbine ◽

Rotor Blade ◽

Positive Influence ◽

Considerable Effect ◽

Flow Angle ◽

Guide Vanes ◽

Control Stage ◽

Wide Range ◽

Flow Effects

The subject of this paper is the optimization of a steam turbine impulse wheel control stage by flow path profiling of the shroud. The investigated control stage is derived from an existing industrial steam turbine design. The shroud contour is varied in radial direction within specified restrictions by an evolutionary algorithm. The algorithm is directly connected to a mesh generator and a CFD solver. The optimization goal is the reduction of the total pressure loss over the guide vanes. The geometry of the rotor blade has been retained unchanged within the presented investigations. The flow field of the varied stage is compared with the baseline geometry. The optimum candidates are further investigated with CFD simulations for different operating point scenarios. Numerical results show that the axisymetric flowpath profiling of the shroud has a considerable effect on the loss behavior of the whole stage over a wide range of pressure ratios. Due to flowpath profiling the boundary layer in the nozzle is significantly affected which results in a more uniformly shaped exit flow angle profile over the nozzle span and a significant reduction of the global secondary flow effects in the guide vanes. Both observations have a positive influence on the flow conditions to the subsequent rotor blade.

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Characteristics of Volcanic Ash in a Gas Turbine Combustor and Nozzle Guide Vanes

Journal of Engineering for Gas Turbines and Power ◽

10.1115/1.4038523 ◽

2018 ◽

Vol 140 (7) ◽

Cited By ~ 3

Author(s):

Lei-Yong Jiang ◽

Yinghua Han ◽

Prakash Patnaik

Keyword(s):

Gas Turbine ◽

Volcanic Ash ◽

Inlet Temperature ◽

Gas Turbine Combustor ◽

Flow Passage ◽

Guide Vanes ◽

Cooling Flow ◽

Cooling Passage ◽

Nozzle Guide ◽

Nozzle Guide Vanes

To understand the physics of volcanic ash impact on gas turbine hot-components and develop much-needed tools for engine design and fleet management, the behaviors of volcanic ash in a gas turbine combustor and nozzle guide vanes (NGV) have been numerically investigated. High-fidelity numerical models are generated, and volcanic ash sample, physical, and thermal properties are identified. A simple critical particle viscosity—critical wall temperature model is proposed and implemented in all simulations to account for ash particles bouncing off or sticking on metal walls. The results indicate that due to the particle inertia and combustor geometry, the volcanic ash concentration in the NGV cooling passage generally increases with ash size and density, and is less sensitive to inlet velocity. It can reach three times as high as that at the air inlet for the engine conditions and ash properties investigated. More importantly, a large number of the ash particles entering the NGV cooling chamber are trapped in the cooling flow passage for all four turbine inlet temperature conditions. This may reveal another volcanic ash damage mechanism originated from engine cooling flow passage. Finally, some suggestions are recommended for further research and development in this challenging field. To the best of our knowledge, it is the first study on detailed ash behaviors inside practical gas turbine hot-components in the open literature.

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