scholarly journals The GT24/26 Low Pressure Turbine

1998 ◽  
Author(s):  
Ian K. Jennions ◽  
Thomas Sommer ◽  
Bernhard Weigand ◽  
Manfred Aigner
Keyword(s):  
Gas Turbines ◽  
Low Pressure ◽  
Thermal Design ◽  
Component Technology ◽  
Test Facility ◽  
3D Analysis ◽  
Leakage Flows ◽  
Low Pressure Turbine ◽  
Point Data ◽  
Lp Turbine

The GT24 and GT26 are the latest in a series of gas turbines from ABB. The GT24 is a 60 Hz, 183 MW turbine, while the GT26 is its (scaled) 50 Hz equivalent, producing 265 MW. They feature a 22 stage controlled diffusion aerofoil compressor, two combustors separated by a single stage high pressure turbine with a four stage low pressure (LP) turbine following the second combustor. This arrangement permits very high efficiencies while avoiding high temperatures and the need to use new, expensive materials. The first GT24 was delivered to Jersey Central Power and Light, Gilbert, New Jersey, USA, at the end of 1995 and achieved baseload operation in May 1996. The engine was highly instrumented with some 1200 measurement points to evaluate component performance. Subsequently, a through-flow datamatch to the design point data was made for the LP turbine and is compared to a full 3D multistage analysis in this paper. The 3D analysis accounts for all the cooling and leakage flows that enter the turbine flowpath and maintains a steady flow calculation by means of interface planes between each blade row that remove any circumferential non-uniformity from the computational flow field. To complement this aerodynamic analysis, some heat transfer results from the ABB GT26 test facility in Birr, Switzerland are also shown. The paper demonstrates how component technology for the first stage was verified at four universities and research centers concurrently with the design process. This experimental data supplemented the existing databases and engendered confidence in the overall aero/thermal design approach.

Inverse Fin Arrangement in a Low Pressure Turbine to Improve the Interaction Between Shroud Leakage Flows and Main Flow

2011 ◽  
Author(s):  
Inga Mahle ◽  
Roman Schmierer
Keyword(s):  
Axial Velocity ◽  
Gas Turbines ◽  
Low Pressure ◽  
Flow Path ◽  
Main Flow ◽  
Leakage Flow ◽  
Wall Region ◽  
Leakage Flows ◽  
Low Pressure Turbine ◽  
Mixing Losses

The paper deals with the geometry of the shroud cavities in low pressure gas turbines and presents a design which helps to reduce the losses that arise when the shroud leakage flows interact with the main flow. The fins in low pressure gas turbines are usually attached to the shroud of the blades. They are therefore rotating while the non-rotating honeycomb or abrasive coating is mounted into the casing. The shroud leakage flow, after passing the rear fin, is decelerated in the rear cavity chamber and enters the main flow path with an axial velocity that is smaller than the axial velocity of the main flow. This difference in axial velocity, together with differences in the circumferential velocity, leads to increased turbulence, mixing losses and an unfavorable incidence of the subsequent vane row in the wall region. Contrarily to the usual configuration, the inverse fins in the turbine presented in the paper are attached to the casing while the honeycomb is mounted onto the rotating blades. This arrangement results in the location of the gap between the fin and the honeycomb being very close to the position of re-entry of the leakage flow into the main flow. Therefore, the leakage flow keeps a high velocity resulting from the narrow fin gap until re-entry which reduces the velocity difference with respect to the main flow. Consequently, the mixing losses and subsequent row losses are reduced. Due to the favorable position of the gap and a particular shaping of the honeycomb, the leakage flow is kept close to the surface of the shroud and enters the main flow with little perturbations. The paper presents numerical results of steady 3D simulations of a three-stage low pressure turbine. Results with an ideal flow path (no cavities), with shroud cavities with conventionally rotating fins and with shroud cavities with inverse fins are compared.

The Effect of Rotor Casing on Low-Pressure Steam Turbine and Diffuser Interactions

2016 ◽  
Vol 139 (2) ◽  
Author(s):  
Gursharanjit Singh ◽  
Andrew P. S. Wheeler ◽  
Gurnam Singh
Keyword(s):  
Steam Turbine ◽  
Computational Study ◽  
Low Pressure ◽  
Computational Method ◽  
Test Facility ◽  
Leakage Flows ◽  
Flow Features ◽  
Last Stage ◽  
Lp Turbine ◽  
Tip Leakage Flows

The present study aims to investigate the interaction between a last-stage steam turbine blade row and diffuser. This work is carried out using computational fluid dynamics (CFD) simulations of a generic last-stage low-pressure (LP) turbine and axial–radial exhaust diffuser attached to it. In order to determine the validity of the computational method, the CFD predictions are first compared with data obtained from an experimental test facility. A computational study is then performed for different design configurations of the diffuser and rotor casing shapes. The study focuses on typical flow features such as effects of rotor tip leakage flows and subsequent changes in the rotor–diffuser interactions. The results suggest that the rotor casing shape influences the rotor work extraction capability and yields significant improvements in the diffuser static pressure recovery.

The Effect of Rotor Casing on Low Pressure Steam Turbine and Diffuser Interactions

2015 ◽  
Author(s):  
Gursharanjit Singh ◽  
Gurnam Singh ◽  
Andrew P. S. Wheeler
Keyword(s):  
Steam Turbine ◽  
Computational Study ◽  
Low Pressure ◽  
Computational Method ◽  
Test Facility ◽  
Leakage Flows ◽  
Flow Features ◽  
Last Stage ◽  
Lp Turbine ◽  
Tip Leakage Flows

The present study aims to investigate the interaction between a last-stage steam turbine blade row and diffuser. This work is carried out using CFD simulations of a generic last stage low pressure (LP) turbine and axial-radial exhaust diffuser attached to it. In order to determine the validity of the computational method, the CFD predictions are first compared with data obtained from an experimental test facility. A computational study is then performed for different design configurations of the diffuser and rotor casing shapes. The study focuses on typical flow features such as effects of rotor tip leakage flows and subsequent changes in the rotor-diffuser interactions. The results suggest that the rotor casing shape influences the rotor work extraction capability and yields significant improvements in the static pressure recovery.

Redesign of High-Lift LP-Turbine Airfoils for Low Speed Testing

2010 ◽  
Author(s):  
Michele Marconcini ◽  
Filippo Rubechini ◽  
Roberto Pacciani ◽  
Andrea Arnone ◽  
Francesco Bertini
Keyword(s):  
Separated Flow ◽  
Low Pressure ◽  
High Lift ◽  
Low Speed ◽  
Low Pressure Turbine ◽  
Wide Range ◽  
Flow Configurations ◽  
Artificial Neural Network Ann ◽  
Lp Turbine ◽  
Turbine Airfoils

Low pressure turbine airfoils of the present generation usually operate at subsonic conditions, with exit Mach numbers of about 0.6. To reduce the costs of experimental programs it can be convenient to carry out measurements in low speed tunnels in order to determine the cascades performance. Generally speaking, low speed tests are usually carried out on airfoils with modified shape, in order to compensate for the effects of compressibility. A scaling procedure for high-lift, low pressure turbine airfoils to be studied in low speed conditions is presented and discussed. The proposed procedure is based on the matching of a prescribed blade load distribution between the low speed airfoil and the actual one. Such a requirement is fulfilled via an Artificial Neural Network (ANN) methodology and a detailed parameterization of the airfoil. A RANS solver is used to guide the redesign process. The comparison between high and low speed profiles is carried out, over a wide range of Reynolds numbers, by using a novel three-equation, transition-sensitive, turbulence model. Such a model is based on the coupling of an additional transport equation for the so-called laminar kinetic energy (LKE) with the Wilcox k–ω model and it has proven to be effective for transitional, separated-flow configurations of high-lift cascade flows.

Transition Mechanisms in Laminar Separated Flow Under Simulated Low Pressure Turbine Aerofoil Conditions

2012 ◽  
Vol 135 (1) ◽  
Author(s):  
Jerrit Dähnert ◽  
Christoph Lyko ◽  
Dieter Peitsch
Keyword(s):  
Reynolds Number ◽  
Separation Bubble ◽  
Separated Flow ◽  
Low Pressure ◽  
Main Flow ◽  
Test Facility ◽  
Flow Conditions ◽  
Laminar Separation ◽  
Free Stream Turbulence ◽  
Low Pressure Turbine

Based on detailed experimental work conducted at a low speed test facility, this paper describes the transition process in the presence of a separation bubble with low Reynolds number, low free-stream turbulence, and steady main flow conditions. A pressure distribution has been created on a long flat plate by means of a contoured wall opposite of the plate, matching the suction side of a modern low-pressure turbine aerofoil. The main flow conditions for four Reynolds numbers, based on suction surface length and nominal exit velocity, were varied from 80,000 to 300,000, which covers the typical range of flight conditions. Velocity profiles and the overall flow field were acquired in the boundary layer at several streamwise locations using hot-wire anemometry. The data given is in the form of contours for velocity, turbulence intensity, and turbulent intermittency. The results highlight the effects of Reynolds number, the mechanisms of separation, transition, and reattachment, which feature laminar separation-long bubble and laminar separation-short bubble modes. For each Reynolds number, the onset of transition, the transition length, and the general characteristics of separated flow are determined. These findings are compared to the measurement results found in the literature. Furthermore, the experimental data is compared with two categories of correlation functions also given in the literature: (1) correlations predicting the onset of transition and (2) correlations predicting the mode of separated flow transition. Moreover, it is shown that the type of instability involved corresponds to the inviscid Kelvin-Helmholtz instability mode at a dominant frequency that is in agreement with the typical ranges occurring in published studies of separated and free-shear layers.

Investigation of Variated Unsteady Inflow Boundary Conditions on the Transition Behavior of a Low Pressure Turbine Cascade Family

2014 ◽  
Author(s):  
Franz F. Blaim ◽  
Roland E. Brachmanski ◽  
Reinhard Niehuis
Keyword(s):  
Boundary Condition ◽  
Transport Equation ◽  
Flow Separation ◽  
Total Pressure ◽  
Low Pressure ◽  
Test Facility ◽  
Number Range ◽  
Pressure Losses ◽  
Low Pressure Turbine ◽  
Transition Behavior

The objective of this paper is to analyze the influence of incoming periodic wakes, considering the variable width, on the integral total pressure loss for two low pressure turbine (LPT) airfoils. In order to reduce the overall weight of a LPT, the pitch to chord ratio was continuously increased, during the past decades. However, this increase encourages the development of the transition phenomena or even flow separation on the suction side of the blade. At low Reynolds numbers, large separation bubbles can occur there, which are linked with high total pressure losses. The incoming wakes of the upstream blades are known to trigger early transition, leading to a reduced risk of flow separation and hence minor integral total pressure losses caused by separation. For the further investigation of these effects, different widths of the incoming wakes will be examined in detail, here. This variation is carried out by using the numerical Unsteady Reynolds Averaged Solver TRACE developed by the DLR Cologne in collaboration with MTU Aero Engines AG. For the variation of the width of the wakes, a variable boundary condition was modeled, which includes the wake vorticity parameters. The width of the incoming wakes was used as the relevant variable parameter. The implemented boundary condition models the unsteady behavior of the incoming wakes by the variation of the velocity profile, using a prescribed frequenc. TRACE can use two different transition models; the main focus here is set to the γ–Reθt transition model, which uses local variables in a transport equation, to trigger the transition within the turbulence transport equation system. The experimental results were conducted at the high speed cascade open loop test facility at the Institute for Jet Propulsion at the University of the German Federal Armed Forces in Munich. For the investigation presented here, two LPT profiles — which were designed with a similar inlet angle, turning, and pitch are analyzed. However, with a common exit Mach number and a similar Reynolds number range between 40k and 400k, one profile is front loaded and the other one is aft loaded. Numerical unsteady results are in good agreement with the conducted measurements. The influence of the width of the wake on the time resolved transition behavior, represented by friction coefficient plots and momentum loss thickness will be analyzed in this paper.

scholarly journals Aero-Thermal Design and Testing of Advanced Turbine Blades

1997 ◽  
Author(s):  
M. Haendler ◽  
D. Raake ◽  
M. Scheurlen
Keyword(s):  
Gas Turbines ◽  
Full Range ◽  
Turbine Blades ◽  
Design Procedure ◽  
Thermal Design ◽  
Test Facility ◽  
Optical Pyrometer ◽  
Electrical Systems ◽  
Operation Conditions ◽  
Improved Performance

Based on the experience gained with more than 80 machines operating worldwide in 50 and 60 Hz electrical systems respectively, Siemens has developed a new generation of advanced gas turbines which yield substantially improved performance at a higher output level. This “3A-Series” comprises three gas turbine models ranging from 70 MW to 240 MW for 50 Hz and 60 Hz power generation applications. The first of the new advanced gas turbines with 170 MW and 3600 rpm was tested in the Berlin factory test facility under the full range of operation conditions. It was equipped with various measurement systems to monitor pressures, gas and metal temperatures, clearances, strains, vibrations and exhaust emissions. This paper presents the aero-thermal design procedure of the highly thermal loaded film cooled first stage blading. The predictions are compared with the extensive optical pyrometer measurements taken at the Siemens test facility on the V84.3A machine under full load conditions. The pyrometer was inserted at several locations in the turbine and radially moved giving a complete surface temperature information of the first stage vanes and blades.

Experimental Study on the Effect of Clocking on the Propagation of Inflow Pressure Distortions in a Low Pressure Turbine Stage

2020 ◽  
Author(s):  
L. Simonassi ◽  
M. Zenz ◽  
P. Bruckner ◽  
S. Pramstrahler ◽  
F. Heitmeir ◽  
...  
Keyword(s):  
Experimental Study ◽  
Flow Field ◽  
Total Pressure ◽  
Low Pressure ◽  
Vibration Characteristics ◽  
Test Facility ◽  
Turbine Stage ◽  
Rotor Vibration ◽  
Low Pressure Turbine ◽  
The Impact

Abstract The design of modern aero engines enhances the interaction between components and facilitates the propagation of circumferential distortions of total pressure and temperature. As a consequence, the inlet conditions of a real turbine have significant spatial non-uniformities, which have direct consequences on both its aerodynamic and vibration characteristics. This work presents the results of an experimental study on the effects of different inlet total pressure distortion-stator clocking positions on the propagation of total pressure inflow disturbances through a low pressure turbine stage, with a particular focus on both the aerodynamic and aeroelastic performance. Measurements at a stable engine relevant operating condition and during transient operation were carried out in a one and a half stage subsonic turbine test facility at the Institute of Thermal Turbomachinery and Machine Dynamics at Graz University of Technology. A localised total pressure distortion was generated upstream of the stage in three different azimuthal positions relative to the stator vanes. The locations were chosen in order to align the distortion directly with a vane leading edge, suction side and pressure side. Additionally, a setup with clean inflow was used as reference. Steady and unsteady aerodynamic measurements were taken downstream of the investigated stage by means of a five-hole-probe (5HP) and a fast response aerodynamic pressure probe (FRAPP) respectively. Strain gauges applied on different blades were used in combination with a telemetry system to acquire the rotor vibration data. The aerodynamic interactions between the stator and rotor rows and the circumferential perturbation were studied through the identification of the main structures constituting the flow field. This showed that the steady and unsteady alterations created by the distortion in the flow field lead to modifications of the rotor vibration characteristics. Moreover, the importance of the impact that the pressure distortion azimuthal position has on the LPT stage aerodynamics and vibrations was highlighted.

Application of the Rotating Water Table to Nozzle Wake Excitation in Low Pressure Turbines

1985 ◽  
Author(s):  
Shun Chen
Keyword(s):  
Water Table ◽  
Low Pressure ◽  
Test Facility ◽  
Test Results ◽  
Unsteady Forces ◽  
Low Pressure Turbine ◽  
Rotating Blade ◽  
Stator Vane ◽  
Two Dimensional Flow ◽  
Hydraulic Analogy

The hydraulic analogy was employed in a rotating water table for simulating the compressible two dimensional flow in a low pressure turbine stage. Both steady and unsteady forces were measured directly on a rotating blade in a blade row rotating concentrically with a row of stator vanes. With proper modeling of the simulation, it is shown that the rotating water table can yield results that agree favorably with the analytical predictions and turbine test results. Using this test facility, the effects of axial spacing between rotor and stator rows on the nozzle wake excitation have been investigated for two different stator vane profiles. The water table test results correlate qualitatively with the turbine test data. The cancellation of nozzle passing frequency excitation by off-setting nozzle pitch was demonstrated in the water table and the results compared with both the analytical predictions and the laboratory turbine test results.

Experimental Investigation of Vane Clocking in a One and 1/2 Stage High Pressure Turbine

2004 ◽  
Author(s):  
Charles W. Haldeman ◽  
Michael G. Dunn ◽  
John W. Barter ◽  
Brian R. Green ◽  
Robert F. Bergholz
Keyword(s):  
High Pressure ◽  
Low Pressure ◽  
Test Facility ◽  
Maximum Efficiency ◽  
High Pressure Turbine ◽  
Data Set ◽  
Time Resolved ◽  
Low Pressure Turbine ◽  
Turbine Vane ◽  
Vane Clocking

Aerodynamic measurements were acquired on a modern single-stage, transonic, high-pressure turbine with the adjacent low-pressure turbine vane row (a typical civilian one and one-half stage turbine rig) to observe the effects of low-pressure turbine vane clocking on overall turbine performance. The turbine rig (loosely referred to in this paper as the stage) was operated at design corrected conditions using the Ohio State University Gas Turbine Laboratory Turbine Test Facility (TTF). The research program utilized uncooled hardware in which all three airfoils were heavily instrumented at multiple spans to develop a full clocking dataset. The low-pressure turbine vane row (LPTV) was clocked relative to the high-pressure turbine vane row (HPTV). Various methods were used to evaluate the influence of clocking on the aeroperformance (efficiency) and the aerodynamics (pressure loading) of the LPTV, including time-resolved and time-averaged measurements. A change in overall efficiency of approximately 2–3% due to clocking effects is demonstrated and could be observed using a variety of independent methods. Maximum efficiency is obtained when the time-average surface pressures are highest on the LPTV and the time-resolved surface pressure (both in the time domain and frequency domain) show the least amount of variation. The overall effect is obtained by integrating over the entire airfoil, as the three-dimensional effects on the LPTV surface are significant. This experimental data set validates several computational research efforts that suggested wake migration is the primary reason for the perceived effectiveness of vane clocking. The suggestion that wake migration is the dominate mechanism in generating the clocking effect is also consistent with anecdotal evidence that fully cooled engine rigs do not see a great deal of clocking effect. This is consistent since the additional disturbances induced by the cooling flows and/or the combustor make it extremely difficult to find an alignment for the LPTV given the strong 3D nature of modern high-pressure turbine flows.

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