scholarly journals Analysis of ultra-low uncertainty gas turbine flow capacity measurement techniques

2020 ◽  
pp. 095765092090971
Author(s):  
Daniel Burdett ◽  
Chris Hambidge ◽  
Thomas Povey
Keyword(s):  
Gas Turbine ◽  
Guide Vane ◽  
Pressure Ratio ◽  
Measurement Techniques ◽  
Operating Cost ◽  
Capacity Measurement ◽  
Early Assessment ◽  
Trailing Edge ◽  
Flow Capacity ◽  
Inlet Conditions

Accurate assessment of nozzle guide vane (NGV) capacity is essential for understanding engine performance data, and to achieve accurate turbine stage matching. In accelerated engine development programmes in particular, accurate and early assessment of NGV capacity is a significant advantage. Whilst the capabilities of computational methods have improved rapidly in recent years, the accuracy of absolute capacity prediction capability is lower than experimental techniques by some margin. Thus, experimental measurement of NGV capacity is still regarded as an essential part of many engine programmes. The semi-transient capacity measurement technique, developed and refined at the University of Oxford over the last 10 years, allows rapid and accurate measurement of engine component (typically fully cooled NGVs) capacity at engine-representative conditions of Mach and Reynolds numbers and coolant-to-mainstream pressure ratio. The technique has been demonstrated to offer considerable advantages over traditional (industrial steady-state) techniques in terms of accuracy, time and operating cost. Since the original facility was constructed, the facility has been modularised to allow for rapid interchange of test vane modules, and the instrumentation has been optimised to drive down the uncertainty in NGV capacity. In this paper, these improvements are described in detail, and a detailed uncertainty analysis is presented of the original facility, the current facility, and a proposed future facility in which the uncertainty of the measurement has been driven down to a practical limit. The bias errors of the three facilities are determined to be ±0.535%, ± 0.495% and ±0.301%, respectively (to 95% confidence). The corresponding precision uncertainties are ±0.028%, ±0.025% and ±0.025%, respectively. The extremely low precision uncertainty in particular allows very small changes in capacity to be resolved. This, combined with rapid interchangeability of test modules, allows studies of the sensitivity of capacity to secondary influences with much greater flexibility than was previously possible. Consideration is also given to the definition of vane capacity in systems with several streams at different conditions of inlet total pressure and temperature. A typical high pressure (HP) NGV has three distinct streams: a mainstream flow; coolant flow ejected from film cooling holes (distributed over the vane surface); and trailing edge coolant ejection. Whilst it is helpful for the coolant mass flow rates and inlet temperatures to be included in the definition, only a relatively small difference arises from the way in which this is achieved. Several definitions appear to share similar usefulness in terms of their robustness to changing inlet conditions of individual streams, but the favoured definition offers the possibility of isolating sensitivities to key effects such as trailing edge coolant ejection. This is achieved by explicitly expressing vane capacity as a function of two controlling pressure ratios. The overall purpose of this paper is to review and analyse in detail the current state-of-the-art in gas turbine flow capacity measurement.

scholarly journals A Proper Shape of the Trailing Edge Modification to Solve a Housing Damage Problem in a Gas Turbine Power Plant

Processes ◽  
2021 ◽  
Vol 9 (4) ◽  
pp. 705
Author(s):  
Thodsaphon Jansaengsuk ◽  
Mongkol Kaewbumrung ◽  
Wutthikrai Busayaporn ◽  
Jatuporn Thongsri
Keyword(s):  
Power Plant ◽  
Gas Turbine ◽  
Structural Dynamics ◽  
Pressure Ratio ◽  
Equivalent Stress ◽  
Total Deformation ◽  
Trailing Edge ◽  
Housing Damage ◽  
The Difference ◽  
Gas Turbine Power Plant

To solve the housing damage problem of a fractured compressor blade (CB) caused by an impact on the inner casing of a gas turbine in the seventh stage (from 15 stages), modifications of the trailing edge (TE) of the CB have been proposed, namely 6.5 mm curved cutting and a combination of 4 mm straight cutting with 6.5 mm curved cutting. The simulation results of the modifications in both aerodynamics variables Cl and Cd and the pressure ratio, including structural dynamics such as a normalized power spectrum, frequency, total deformation, equivalent stress, and the safety factor, found that 6.5 mm curved cutting could deliver the aerodynamics and structural dynamics similar to the original CB. This result also overcomes the previous work that proposed 5.0 mm straight cutting. This work also indicates that the operation of a CB gives uneven pressure and temperature, which get higher in the TE area. The slightly modified CB can present the difference in the properties of both the aerodynamics and the structural dynamics. Therefore, any modifications of the TE should be investigated for both properties simultaneously. Finally, the results from this work can be very useful information for the modification of the CB in the housing damage problem of the other rotating types of machinery in a gas turbine power plant.

Dry, Low Emissions for the ‘H’ Heavy-Duty Industrial Gas Turbines: Full-Scale Combustion System Rig Test Results

2003 ◽  
Author(s):  
Geoff Myers ◽  
Dan Tegel ◽  
Markus Feigl ◽  
Fred Setzer ◽  
William Bechtel ◽  
...  
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Pressure Ratio ◽  
Combined Cycle ◽  
Full Scale ◽  
Combustion System ◽  
Heavy Duty ◽  
Test Program ◽  
Industrial Gas Turbines ◽  
Inlet Conditions

The lean, premixed DLN2.5H combustion system was designed to deliver low NOx emissions from 50% to 100% load in both the Frame 7H (60 Hz) and Frame 9H (50 Hz) heavy-duty industrial gas turbines. The H machines employ steam cooling in the gas turbine, a 23:1 pressure ratio, and are fired at 1440 C (2600 F) to deliver over-all thermal efficiency for the combined-cycle system near 60%. The DLN2.5H combustor is a modular can-type design, with 14 identical chambers used on the 9H machine, and 12 used on the smaller 7H. On a 9H combined-cycle power plant, both the gas turbine and steam turbine are fired using the 14-chamber DLN2.5H combustion system. An extensive full-scale, full-pressure rig test program developed the fuel-staged dry, low emissions combustion system over a period of more than five years. Rig testing required test stand inlet conditions of over 50 kg/s at 500 C and 28 bar, while firing at up to 1440 C, to simulate combustor operation at base load. The combustion test rig simulated gas path geometry from the discharge of the annular tri-passage diffuser through the can-type combustion liner and transition piece, to the inlet of the first stage turbine nozzle. The present paper describes the combustion system, and reports emissions performance and operability results over the gas turbine load and ambient temperature operating range, as measured during the rig test program.

Development of the Transpiration Air-Cooled Turbine for High-Temperature Dirty Gas Streams

1983 ◽  
Vol 105 (4) ◽  
pp. 821-825 ◽  
Author(s):  
J. Wolf ◽  
S. Moskowitz
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Power Plants ◽  
Pressure Ratio ◽  
Combined Cycle ◽  
Specific Power ◽  
Skin Permeability ◽  
Air Cooling ◽  
Initial Exposure ◽  
Flow Capacity

Studies of combined cycle electic power plants have shown that increasing the firing temperature and pressure ratio of the gas turbine can substantially improve the specific power output of the gas turbine as well as the combined cycle plant efficiency. Clearly this is a direction in which we can proceed to conserve the world’s dwindling petroleum fuel supplies. Furthermore, tomorrow’s gas turbines must do more than operate at higher temperature; they will likely face an aggressive hot gas stream created by the combustion of heavier oils or coal-derived liquid or gaseous fuels. Extensive tests have been performed on two rotating turbine rigs, each with a transpiration air cooled turbine operating in the 2600 to 3000°F (1427 to 1649°C) temperature range at increasing levels of gas stream particulates and alkali metal salts to simulate operation on coal-derived fuel. Transpiration air cooling was shown to be effective in maintaining acceptable metal temperatures, and there was no evidence of corrosion, erosion, or deposition. The rate of transpiration skin cooling flow capacity exhibited a minor loss in the initial exposure to the particulate laden gas stream of less than 100 hours, but the flow reduction was commensurate with that produced by normal oxidation of the skin material at the operating temperatures of 1350°F (732°C). The data on skin permeability loss from both cascade and engine tests compared favorably with laboratory furnace oxidation skin specimens. To date, over 10,000 hr of furnace exposure has been conducted. Extrapolation of the data to 50,000 hr indicates the flow capacity loss would produce an acceptable 50°F (10°C) increase in skin operating temperature.

Online Performance Monitoring of Industrial Compressors Using Meanline Modelling

2014 ◽  
Author(s):  
Matteo Cicciotti ◽  
Dionysios P. Xenos ◽  
Ala E. F. Bouaswaig ◽  
Nina F. Thornhill ◽  
Ricardo F. Martinez-Botas
Keyword(s):  
Performance Monitoring ◽  
Guide Vane ◽  
Pressure Ratio ◽  
Inlet Guide Vane ◽  
Mechanical Degradation ◽  
Adaptive Parameters ◽  
Online Performance Monitoring ◽  
Constrained Minimization Problem ◽  
Inlet Conditions ◽  
Process Measurements

This paper proposes a framework for detecting mechanical degradation online and assessing its effect on the performance of industrial compressors. It consists of a model of the machine in undegraded condition and of a degradation adaptive model. The proposed methodology for online degradation detection differentiates itself from those found in the literature as the undegraded model is not linearized and ambient/inlet conditions are explicitly taken into account. The degradation is modelled through adaptive parameters which are estimated and updated online through the solution of a constrained minimization problem within a moving window. It uses available process measurements of flow, pressures, temperatures and composition. The update of the parameters guarantees the model accuracy and it permits the estimation of the effects of mechanical degradation away from the compressor running line. The performance monitoring framework has been successfully applied on an industrial air centrifugal compressor. It was found that after 3250 hours of operation from the previous maintenance the efficiency and the pressure ratio had dropped approximately 5.5% and 2.5% of their respective undegraded values. Furthermore, it was found that the performance deviations from the baseline depend from the position of the operative point in the performance map. In fact, the pressure ratio drop was lower (2%) and efficiency drop was higher (6%) for lower inlet guide vanes opening whereas pressure ratio drop was higher (3%) and efficiency drop was lower (1.6%) for higher inlet guide vane opening.

scholarly journals The Influence of Blade Leaning on the Performance of an Integrated OGV-Diffuser System

1991 ◽  
Author(s):  
J. F. Carrotte ◽  
S. J. Stevens ◽  
A. P. Wray
Keyword(s):  
Static Pressure ◽  
Guide Vane ◽  
Integrated Design ◽  
Outer Wall ◽  
Flow Conditions ◽  
Trailing Edge ◽  
Outlet Angle ◽  
Lean Angle ◽  
Wall Flow ◽  
Inlet Conditions

An experimental investigation has been carried out to study the performance of an integrated design of compressor outlet guide vane and combustor pre-diffuser system. The trailing edge of each OGV was located within the outwardly canted diffuser by a distance equal to 27% of the diffuser axial length. In order to obtain representative inlet conditions a rotor, providing a fully sheared velocity profile and an air outlet angle of approximately 40°, was located upstream of the OGVs. Compared with the measured performance when the trailing edge of each OGV was located at diffuser inlet, a small increase in total pressure loss and a corresponding decrease in static pressure recovery was observed for the shortened system. This change in performance reflected a deterioration in the flow conditions along the outer wall, with transitory stalling of the flow being observed at diffuser exit. By leaning the blades in a circumferential direction through angles of 10° and 15° the outer wall flow conditions could be progressively improved, although at the largest angle tested stalling of the flow occurred at the hub of each OGV. However, at a lean angle of 10° the performance, in terms of loss and flow stability, could be virtually restored to the levels obtained when the trailing edge of each OGV was located radially at diffuser inlet.

scholarly journals A Numerical Study of Chemically Reactive Flow of Hot Combustion Gases in a First-Stage Turbine Nozzle

1997 ◽  
Author(s):  
Th. Godin ◽  
S. Harvey ◽  
P. Stouffs
Keyword(s):  
Gas Turbine ◽  
Numerical Study ◽  
Guide Vane ◽  
Chemical Reactivity ◽  
Pollutant Emission ◽  
Reactive Flow ◽  
Inlet Temperature ◽  
Chemical Reaction Kinetics ◽  
Combustion Gases ◽  
Inlet Conditions

Current progress in gas turbine performance is achieved mainly by increasing the turbine inlet temperature. At high temperature levels (>2000K), the hot combustion gases can no longer be considered as chemically inert, and it becomes important to account for dissociation and recombination reactions occurring not only in the combustion chamber but also within the expanding gas stream in the turbine. In this paper, the authors present a two-dimensional numerical study of chemically reactive flow of hot combustion gases through the first guide vane of a gas turbine. For this initial study, simplified boundary conditions are assumed: blade cooling air mixing is neglected, the blade wall temperature is assigned a fixed value, and uniform inlet conditions are assumed. This study investigates the effect of turbulence on chemical reaction kinetics and presents pollutant emission levels at the nozzle exit. Particular attention is also focussed on chemical reactivity near the pressure and suction sides of the turbine guide vane blades.

Using Hydrogen as Gas Turbine Fuel

2005 ◽  
Vol 127 (1) ◽  
pp. 73-80 ◽  
Author(s):  
Paolo Chiesa ◽  
Giovanni Lozza ◽  
Luigi Mazzocchi
Keyword(s):  
Natural Gas ◽  
Gas Turbine ◽  
Guide Vane ◽  
Volume Flow Rate ◽  
Pressure Ratio ◽  
Combined Cycle ◽  
Point Of View ◽  
Inert Gases ◽  
Detailed Model ◽  
Heavy Duty Gas Turbine

This paper addresses the possibility to burn hydrogen in a large size, heavy-duty gas turbine designed to run on natural gas as a possible short-term measure to reduce greenhouse emissions of the power industry. The process used to produce hydrogen is not discussed here: we mainly focus on the behavior of the gas turbine by analyzing the main operational aspects related to switching from natural gas to hydrogen. We will consider the effects of variations of volume flow rate and of thermophysical properties on the matching between turbine and compressor and on the blade cooling of the hot rows of the gas turbine. In the analysis we will take into account that those effects are largely emphasized by the abundant dilution of the fuel by inert gases (steam or nitrogen), necessary to control the NOx emissions. Three strategies will be considered to adapt the original machine, designed to run on natural gas, to operate properly with diluted hydrogen: variable guide vane (VGV) operations, increased pressure ratio, re-engineered machine. The performance analysis, carried out by a calculation method including a detailed model of the cooled gas turbine expansion, shows that moderate efficiency decays can be predicted with elevated dilution rates (nitrogen is preferable to steam under this point of view). The combined cycle power output substantially increases if not controlled by VGV operations. It represents an opportunity if some moderate re-design is accepted (turbine blade height modifications or high-pressure compressor stages addition).

Influence of Variable Geometry Transients on the Gas Turbine Performance

2011 ◽  
Author(s):  
Joa˜o Roberto Barbosa ◽  
Franco Jefferds dos Santos Silva ◽  
Jesuino Takachi Tomita ◽  
Cleverson Bringhenti
Keyword(s):  
Gas Turbine ◽  
Guide Vane ◽  
Pressure Ratio ◽  
Research Work ◽  
Combined Cycle ◽  
Inlet Guide Vane ◽  
Variable Geometry ◽  
Gas Generator ◽  
Turbine Performance ◽  
Blade Geometry

During the design of a gas turbine it is required the analysis of all possible operating points in the gas turbine operational envelope, for the sake of verification of whether or not the established performance might be achieved. In order to achieve the design requirements and to improve the engine off-design operation, a number of specific analyses must be carried out. This paper deals with the characterization of a small gas turbine under development with assistance from ITA (Technological Institute of Aeronautics), concerning the compressor variable geometry and its transient operation during accelerations and decelerations. The gas turbine is being prepared for the transient tests with the gas generator, whose results will be used for the final specification of the turboshaft power section. The gas turbine design has been carried out using indigenous software, developed specially to fulfill the requirements of the design of engines, as well as the support for validation of research work. The engine under construction is a small gas turbine in the range of 5 kN thrust / 1.2 MW shaft power, aiming at distributed power generation using combined cycle. The work reported in this paper deals with the variable inlet guide vane (VIGV) transients and the engine transients. A five stage 5:1 pressure ratio axial-flow compressor, delivering 8.1 kg/s air mass flow at design-point, is the basis for the study. The compressor was designed using computer programs developed at ITA for the preliminary design (meanline), for the axisymmetric analysis to calculate the full blade geometry (streamline curvature) and for the final compressor geometry definition (3-D RANS and turbulence models). The programs have been used interatively. After the final channel and blade geometry definition, the compressor map was generated and fed to the gas turbine performance simulation program. The transient study was carried out for a number of blade settings, using different VIGV geometry scheduling, giving indication that simulations needed to study the control strategy can be easily achieved. The results could not be validated yet, but are in agreement with the expected engine response when such configuration is used.

Performance Prediction for High Pressure-Ratio Radial Inflow Turbines

2007 ◽  
Author(s):  
Xuwen Qiu ◽  
Nick Baines
Keyword(s):  
High Pressure ◽  
Early Stage ◽  
Pressure Ratio ◽  
Fluid Motion ◽  
Trailing Edge ◽  
Flow Area ◽  
High Pressure Ratio ◽  
Flow Capacity ◽  
Blade Row ◽  
Map Generation

This paper describes the latest developments in a method for predicting the design and off-design performance of radial inflow turbines, using a one-dimensional analysis. As such, it is suitable for preliminary design purposes and also for turbine map generation as an aid to the modelling of systems including such turbines. Previous development work has resulted in methods of loss correlation allowing the power output and efficiency to be predicted with confidence. The focus of this paper is on extending the calculation method to high-pressure ratios, and the accurate prediction of flow capacity for unchoked and choked conditions. A numerical method provides for the identification of subsonic, transonic, and supersonic flow regimes in the bladed rows of the turbine, and allows their solution in a consistent manner. Numerically stable and validated solutions have been obtained for a cryogenic expander case with the stage pressure ratios as high as 13.6. In this paper, we will report cases with pressure ratio up to 4.0, where the nozzle and rotor are operating at the choked condition. When a blade row is choked, the flow capacity depends on the throat area, and accurate predictions require that this area is known with confidence. Previous meanline methods have typically concentrated on unchoked flow conditions, in which it is not necessary to know the throat area accurately. In turbine design, the method thus enables the necessary throat areas to be established at an early stage in the design process, and this information is required for the subsequent blade design. In analysis, comparison with test data has revealed the importance of throat aerodynamic blockage, which has hitherto largely been overlooked in meanline prediction methods. Estimates of appropriate blockages have been obtained from such comparisons. An unusual feature of radial inflow turbine nozzles is the reduction of annulus area downstream of the blade row. This can lead to situations where it is the flow area at the trailing edge rather than the throat that limits the flow capacity in choking conditions. The method accommodates this by introducing additional deviation at the trailing edge to ensure that the throat remains choked for all blade row pressure ratios greater than the critical pressure ratio, and the flow between the throat and trailing edge develops in a form that is fully consistent with the basic principles of fluid motion.

scholarly journals Investigation of the Trailing Edge Modification Effect on Compressor Blade Aerodynamics Using SST k-ω Turbulence Model

Aerospace ◽  
2019 ◽  
Vol 6 (4) ◽  
pp. 48 ◽  
Author(s):  
Kaewbumrung ◽  
Tangsopa ◽  
Thongsri
Keyword(s):  
Gas Turbine ◽  
Turbulence Model ◽  
Pressure Ratio ◽  
Compressor Blade ◽  
Base Line ◽  
Trailing Edge ◽  
Positive Feedbacks ◽  
Modification Effect ◽  
Edge Modification ◽  
Housing Damage

A gas turbine power plant in Thailand had the problem of compressor blade fracture in Stages 6–8, which was caused by housing damage. This gas turbine has a total of 15 stages. The housing damage reduced the lifetime of blades to an unacceptable level. This article shall report the solution and outcomes. Three-dimensional (3D) compressor blade models in the problematic stages were prepared by a 3D scanning machine to find a solution based on computational fluid dynamics (CFD), and then were completed for simulation by adding Stages 5 and 9 to become a multi-stage axial model. The latter models were modified by trimming the trailing edge by 1, 5-, and 10-mm. Using ANSYS CFX R19.2 software, the CFD results of the trailing edge modification effect on flow using the shear stress transport (SST) k-ω turbulence model revealed aerodynamics inside the problematic stages both before and after blade modifications. Modifying the blade by 5 mm was suitable, because it had lesser effects on aerodynamic parameters: pressure ratio, drag, and lift coefficients, when compared to the modification of 10 mm. The larger the modification, the greater the effect on aerodynamics. The effects on aerodynamics were intensified when they were modified by 10 mm. The validation of base line blades was conducted for the overall compressor parameters that were compared with the measurable data. These results were accepted and gave positive feedbacks from engineers who practically applied our reports in a real maintenance period of gas turbine.

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