Unsteady 3D-Numerical Investigation of the Influence of the Blading Design on the Stator-Rotor Interaction in a 2-Stage Turbine

2005 ◽  
Author(s):  
Dieter E. Bohn ◽  
Jing Ren ◽  
Christian Tu¨mmers ◽  
Michael Sell
Keyword(s):  
Gas Turbines ◽  
Flow Characteristics ◽  
Computer Code ◽  
Experimental Investigations ◽  
Blade Design ◽  
Test Rig ◽  
3D Flow ◽  
Two Stage ◽  
Flow Phenomena ◽  
Flow Through

An important goal in the development of turbine bladings is improving their efficiency to achieve an optimized usage of energy resources. This requires a detailed insight into the complex 3D-flow phenomena in multi-stage turbines. In order to investigate the flow characteristics of modern highly loaded turbine profiles, a test rig with a two-stage axial turbine has been set up at the Institute of Steam and Gas Turbines, Aachen University. The test rig is especially designed to investigate different blading designs. In order to analyze the influence of the blade design on the unsteady blade row interaction, the 3D flow through the two-stage turbine is simulated numerically, using an unsteady Navier-Stokes computer code. The investigations include a comparison of two bladings with different design criteria. The reference blading is a commonly used cylindrical designed blading. This blade design will be compared with a bow-blading, which is designed to minimize the secondary flow phenomena near the endwall in order to achieve a balanced mass flow through nearly the whole passage height. The investigations will focus on the different loss behavior of the two bladings. Unsteady profile pressure distributions and radial efficiencies of the two blade designs will be discussed in detail. The flow conditions are taken from experimental investigations performed at the Institute of Steam and Gas Turbines. On the basis of the experiments a validation of the code will be performed by comparing the numerical results to the corresponding experimental data at the inlet and the outlet of the blading.

Influence of the Radial and Axial Gap of the Shroud Cavities on the Flowfield in a 2-Stage Turbine

2006 ◽  
Author(s):  
Dieter Bohn ◽  
Robert Krewinkel ◽  
Christian Tu¨mmers ◽  
Michael Sell
Keyword(s):  
Secondary Flow ◽  
Gas Turbines ◽  
Guide Vane ◽  
Pressure Ratio ◽  
Experimental Investigations ◽  
Test Rig ◽  
3D Flow ◽  
Design Point ◽  
Flow Phenomena ◽  
Radial Gap

An important goal in the development of turbine bladings is to improve their efficiency for an optimized usage of energy resources. This requires a detailed insight into the complex 3D-flow phenomena in multi-stage turbines. In order to investigate the flow characteristics of modern highly loaded turbine profiles a test rig with a two stage axial turbine has been set up at the Institute of Steam and Gas Turbines, RWTH Aachen University. The test rig is especially designed to investigate the influence of different cavity sizes. In order to analyze the influence of the cavity size on the secondary flow and to discuss the effects of the blade loading, the 3D flow through the 2-stage turbine with shrouded blades is investigated numerically, using the steady Navier-Stokes inhouse computer code, CHT-Flow. The turbine blading is designed to concentrate the mass flow in the middle of the passage in order to keep the main flow away from the secondary flow regions at the endwalls of the blade. The simulations include a comparison of a configuration without cavities (design case) and two configurations, where the axial gap between the shroud and the endwalls is about 5 mm and the radial gap between the shroud and the endwall is varied between 0.8 mm (open radial gap) and radial gaps “near zero” (closed radial gap). The investigations are done with focus on the secondary flow phenomena in the second guide vane. For a detailed analysis of the blade load the design point and an off-design point are simulated for each blading. The flow conditions are taken from experimental investigations performed at the Institute of Steam and Gas Turbines, Aachen University. In the experimental setup, the turbine is operated at a low pressure ratio of 1.4 with an inlet pressure of 3.2·105 Pa. The numerical results will also be compared to the corresponding experimental data at the outlet of the second stage.

A Comprehensive Investigation of Preswirled Flow Through Rotating Radial Holes

2014 ◽  
Vol 137 (3) ◽  
Author(s):  
Daniel Riedmüller ◽  
Jan Sousek ◽  
Michael Pfitzner
Keyword(s):  
Experimental Data ◽  
Gas Turbines ◽  
Discharge Coefficient ◽  
Cfd Simulation ◽  
Test Rig ◽  
Outer Annulus ◽  
Flow Phenomena ◽  
Flow Through ◽  
Flow Directions ◽  
Experimental Findings

This paper reports on the flow (centrifugal = radially outward, centripetal = radially inward) through rotating radial orifices with and without preswirl in the flow approaching the orifice in the outer annulus. The aerodynamical behavior of flow through radial rotating holes is different from the one through axial and stationary holes due to the presence of centrifugal and Coriolis forces. To investigate the flow phenomena and the discharge coefficient of these orifices in detail, an existing test rig containing two independently rotating shafts (corotating and counter rotating) was used. To simulate conditions of real gas turbines, where the flow is often influenced by upstream components, various preswirl angles were used in the test rig. Measurements of the flow discharge coefficient in both flow directions through the orifices (centripetal and centrifugal), with and without preswirl generation in the outer annulus, are presented at various flow conditions (pressure ratios across orifices, Mach numbers of approaching flow) and for different geometric parameters (length to diameter ratios, sharp/rounded inlet edges). Flow effects that occur with preswirled flow are clarified. A comparison of the experimental data, for both flow directions, shows a similar behavior of the discharge coefficients with increasing shaft speeds. To supplement the experimental data and to better understand the experimental findings, numerical simulations were performed, which show a good agreement with the experimental results. Furthermore, an optimization model with complete automatic grid generation, computational fluid dynamics (CFD) simulation, and postprocessing, was built to enable large parametric studies, e.g., grid independence of the solutions.

Comparison of 2D and 3D Airfoils in Combination With Non Axisymmetric End Wall Contouring: Part 1 — Experimental Investigations

2016 ◽  
Author(s):  
Tobias W. Zimmermann ◽  
Oliver Curkovic ◽  
Manfred Wirsum ◽  
Andrew Fowler ◽  
Kush Patel
Keyword(s):  
Gas Turbines ◽  
Experimental Investigations ◽  
Test Rig ◽  
Second Stage ◽  
Beneficial Impact ◽  
Flow Phenomena ◽  
2D And 3D ◽  
End Wall ◽  
Constant Section ◽  
Turbine Blading

Tangential end wall contouring is intended to improve turbomachinery blading efficiency. This paper is the first of a series of two papers. It summarizes the experimental investigation of a test turbine with end wall contoured vanes and blades. Constant section airfoils as well as optimized 3D high pressure steam turbine blading in baseline and end wall contoured configurations have been examined in a 2 stage axial turbine test rig at the Institute of Power Plant Technology, Steam and Gas Turbines (IKDG) of RWTH Aachen University. The test rig is driven with air. Brush seals are implemented within the casing sided cavities to minimize the leakage flow near the tip end walls, where the contouring is also applied. The pressure and temperature data that is recorded in three axial measuring planes are plotted to visualize the change in flow structure. This has shown that the efficiency is increased for 2D airfoils by means of end wall contouring, which is caused by a homogenized inflow to the second stage. However the efficiency of the first stage suffers, the end wall contouring is beneficial for the performance of the engine. Both phenomena (an efficiency loss in stage one and an improvement of the performance in stage two) have also been measured for the optimized 3D configurations thus it can be expected that end wall contouring has also a beneficial impact on the performance of multi row turbines. The second part of this paper presents the results of numerical investigations of end-wall contoured blades. It will demonstrate how the secondary flow phenomena are influenced by end-wall contours. The simulations are validated with measured data from the test rig.

scholarly journals Investigation of Flow through a Labyrinth Seal

2021 ◽  
Vol 13 (2) ◽  
pp. 51-58
Author(s):  
Marius ENACHE ◽  
Razvan CARLANESCU ◽  
Andreea MANGRA ◽  
Florin FLOREAN ◽  
Radu KUNCSER
Keyword(s):  
Gas Turbines ◽  
Flow Characteristics ◽  
Labyrinth Seal ◽  
Cfd Modeling ◽  
Gas Temperature ◽  
Continuous Increase ◽  
Seal Design ◽  
Air Temperatures ◽  
Flow Through ◽  
Gas Leaks

Growing performance requirements for gas turbines have led to a continuous increase in gas temperature and pressure ratios. Together with the resulting increase in cooling flows, this requires more and more minimization and control of internal gas leaks. To meet future performance goals, the application of a new seal design and an improved understanding of leakage flow characteristics are of particular importance. The air mass flow through a labyrinth seal designed for a low-pressure turbine has been determined both through analytical calculus and CFD modeling. Different radial clearances and different air temperatures have been considered. In the next stage, the results will be validated through experiments.

scholarly journals Computation of Two-Phase Flows in Low-NOx Combustor Premix Ducts Utilizing Fuel Film Evaporation

1997 ◽  
Author(s):  
Heiko Rosskamp ◽  
Michael Willmann ◽  
Sigmar Wittig
Keyword(s):  
Gas Turbines ◽  
Gas Flow ◽  
Turbulence Modeling ◽  
Coke Formation ◽  
Flow Characteristics ◽  
Computer Code ◽  
Two Phase ◽  
Boundary Layer Equations ◽  
Film Evaporation ◽  
Wall Film

For aircraft gas turbines as well as for industrial gas turbines current and future developments aim at the implementation of lean premixed-prevaporized (LPP) combustor techniques. For the development and optimization of these combustors powerful CFD-codes are required. A new code developed at the Institut für Thermische Strömungsmaschinen (ITS), University of Karlsruhe, provides detailed information on the gas flow as well as on the propagation and evaporation characteristics of liquid wall films inside combustors. The flow characteristics of the gas phase are predicted using a Finite-Volume 3D-Navier-Stokes code with k-ε turbulence modeling. To calculate the evaporation characteristics of a propagating wall film, a two-dimensional wall film model based on the boundary layer equations is proposed. The present paper comprises a comparison between calculations and experiments for the verification of the code and a detailed study on the evaporation characteristics of fuel films. The results obtained allow judgement to be made on the risk of coke formation on the prefilming surface and suggest that in some operating points a LPP combustor can be operated utilizing solely film evaporation. In addition, the computer code developed also accounts for many familiar types of shear driven film flows such as internal prefilming air blast atomizer flows for example.

Efficiency Improvement and Noise Reduction Through Stator-Stator Clocking Effect of a Two-Stage Turbine

2005 ◽  
Author(s):  
Jaroslaw R. Blaszczak
Keyword(s):  
Acoustic Noise ◽  
Experimental Investigations ◽  
Two Stage ◽  
Machine Vibration ◽  
Low Pressure Turbine ◽  
Measurement Results ◽  
Stator Vane ◽  
Flow Phenomena ◽  
Inlet Conditions ◽  
Good Agreement

The objective of the presented test program was to further experimentally investigate vane-indexing effect influence on the performance, noise and vibration of two-stage low-pressure turbine. Keeping the inlet conditions strictly constant during the tests, two turbine stages were experimentally investigated. Herein, some flow measurement results and the external characteristics for different circumferential positions of the stator vanes are described. Comparisons were made with numerical simulation and they showed good agreement. Experimental data and numerical simulations of stator vane surface pressures are presented to determine how the flow phenomena were affected by indexing of the airfoils for two cases: for nominal rotational speed and for off-design turbine conditions. In addition, correlation to acoustic noise and machine vibration level is presented. They have been found to be clocking dependent. The experimental investigations have been carried out on a two-stage turbine research facility at the Institute of Turbomachinery of the Technical University of Lodz, Poland.

Numerical and Experimental Investigations on the Flow in a 4-Stage Turbine With Special Focus on the Development of a Radial Temperature Streak

1999 ◽  
Author(s):  
Dieter Bonn ◽  
Harald Funke ◽  
Jochen Gier
Keyword(s):  
Gas Turbines ◽  
Experimental Investigations ◽  
Recent Experimental Data ◽  
Finite Volume Scheme ◽  
Inlet Temperature ◽  
Special Focus ◽  
Test Rig ◽  
Reference Case ◽  
Mixing Processes ◽  
Radial Temperature

In the development of modern gas turbines the increase of the turbine inlet temperature is restricted by the need to cool the first stages of the turbine. In addition the flow leaving the combustor is thermally inhomogeneous. Since the blade cooling has to be designed for the actual local hot gas temperatures, it is important to know how these temperature inhomogeneities develop and attenuate inside the multistage flow passage. In this investigation the flow inside a 4-stage turbine, which is set up in a test rig at the Institute of Steam and Gas Turbines, Aachen University of Technology, is calculated with a state-of-the-art fully three-dimensional Navier-Stokes solver based on an accurate finite volume scheme. The stator and rotor rows are coupled via mixing planes. The turbine is a scaled down original turbine with realistic axial gaps. The homogeneous reference case is qualified by comparison to recent experimental data gathered at the test rig. Therefore, the flow is extensively measured at several locations. In a second step a radial temperature streak is set at the inlet for the same point of operation. The results show the development of the temperature streak through the four stages. With this information the underlying mixing processes are described and analysed. It is found that the hot streak segregation effect is present in all four stages.

On the Reliability of RANS and URANS Numerical Results for High-Pressure Turbine Simulations: A Benchmark Experimental and Numerical Study on Performance and Interstage Flow Behavior of High-Pressure Turbines at Design and Off-Design Conditions Using Two Different Turbine Designs

2013 ◽  
Vol 135 (6) ◽  
Author(s):  
M. T. Schobeiri ◽  
S. Abdelfattah
Keyword(s):  
High Pressure ◽  
Numerical Study ◽  
Flow Behavior ◽  
Sensitivity Study ◽  
Numerical Results ◽  
Experimental Investigations ◽  
Predictive Capability ◽  
Two Stage ◽  
Flow Through ◽  
And Performance

Improved computational fluid dynamics tools based on Reynolds-averaged Navier–Stokes (RANS) equations have shown that the behavior of simple flow cases can be predicted with a reasonable degree of accuracy. Their predictive capability, however, substantially diminishes whenever major secondary vortices, adverse pressure gradients, and wake-boundary layer interactions are present. Flow through high-pressure (HP) turbine components uniquely incorporates almost all of the above features, interacting with each other and determining the efficiency and performance of the turbine. Thus, the degree of accuracy of predicting the flow through a HP turbine can be viewed as an appropriate benchmark test for evaluating the predictive capability of any RANS-based method. Detailed numerical and experimental investigations of different HP turbines presented in this paper have revealed substantial differences between the experimental and the numerical results pertaining to the individual flow quantities. This paper aims at identifying the quantities whose simulation inaccuracies are pre-eminently responsible for the aforementioned differences. This task requires (a) a meticulous experimental investigation of all individual thermofluid quantities and their interactions resulting in an integral behavior of the turbomachine in terms of efficiency and performance, (b) a detailed numerical investigation using appropriate grid densities based on simulation sensitivity, and (c) steady and transient simulations to ensure their impact on the final numerical results. To perform the above experimental and numerical tasks, two different HP turbines were investigated: (1) a two-stage turbine with moderately compound-leaned stator blades and (2) a three-stage turbine rotor with compound-leaned stator and rotor blades. Both turbines have been thoroughly measured and numerically simulated using RANS and URANS. Detailed interstage radial and circumferential traversing presents a complete flow picture of the second stage. Performance measurements were carried out for design and off-design rotational speeds. For comparison with numerical simulations, the turbines were numerically modeled using a commercially available code. An extensive mesh sensitivity study was performed to achieve a grid-independent accuracy for both steady and transient analysis. Comparison of RANS/URANS results with the experimental ones revealed differences in total pressure for the two-stage turbine of up to 5%. A significantly lower difference of less than 0.2% is observed for the three-stage turbine with specially designed blades to suppress the secondary flow losses. Analyzing the physical background of a RANS-based solver, it was argued that the differences of individual quantities exhibited in the paper were attributed to the deficiencies in dissipation and transition models.

Design and Development of a Two Stage Transonic Axial Flow Compressor

1996 ◽  
Author(s):  
Katsushi Nagai ◽  
Kazuaki Ikesawa ◽  
Takao Sugimoto ◽  
Toshinao Tanaka ◽  
Hiroshi Umino ◽  
...  
Keyword(s):  
Gas Turbines ◽  
Design Method ◽  
Axial Flow ◽  
Test Facility ◽  
Blade Design ◽  
Two Stage ◽  
Circular Arc ◽  
Axial Flow Compressor ◽  
Transonic Compressor ◽  
Flow Compressor

A highly loaded two stage transonic axial flow compressor, which forms a front stages of a multi stage compressor for industrial gas turbines, has been designed and tested. Overall pressure ratio is 2.25 and the first stage rotor tip Mach number is 1.15. Two airfoil types, Double Circular Arc airfoil and Multi Circular Arc airfoil, were designed for a transonic rotor blade under the same condition. MCA blade design method was devised and introduced. The blade design relied heavily on CFD techniques using a Euler code and a Navier Stokes code to cope with a precise treatment. The rig test was conducted by our compressor test facility to verify a validity of the transonic compressor design method and to compare the performance of the DCA and the MCA airfoils. This report describes the aerodynamic design and the test results as well as the test facility and instrumentation.

scholarly journals Numerical Study of the Axial Gap and Hot Streak Effects on Thermal and Flow Characteristics in Two-Stage High Pressure Gas Turbine

Energies ◽  
2018 ◽  
Vol 11 (10) ◽  
pp. 2654 ◽  
Author(s):  
Myung Gon Choi ◽  
Jaiyoung Ryu
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Power Plants ◽  
Numerical Study ◽  
Flow Characteristics ◽  
Suction Side ◽  
Combined Cycle ◽  
Maximum Temperature ◽  
Two Stage ◽  
Second Stage

Combined cycle power plants (CCPPs) are becoming more important as the global demand for electrical power increases. The power and efficiency of CCPPs are directly affected by the performance and thermal efficiency of the gas turbines. This study is the first unsteady numerical study that comprehensively considers axial gap (AG) in the first-stage stator and first-stage rotor (R1) and hot streaks in the combustor outlet throughout an entire two-stage turbine, as these factors affect the aerodynamic performance of the turbine. To resolve the three-dimensional unsteady-state compressible flow, an unsteady Reynolds-averaged Navier–Stokes (RANS) equation was used to calculate a k-ω SST γ turbulence model. The AG distance d was set as 80% (case 1) and 120% (case 3) for the design value case 2 (13 mm or d/Cs1 = 0.307) in a GE-E3 gas turbine model. Changes in the AG affect the overall flow field characteristics and efficiency. If AG decreases, the time-averaged maximum temperature and pressure of R1 exhibit differences of approximately 3 K and 400 Pa, respectively. In addition, the low-temperature zone around the hub and tip regions of R1 and second-stage rotor (R2) on the suction side becomes smaller owing to a secondary flow and the area-averaged surface temperature increases. The area-averaged heat flux of the blade surface increases by a maximum of 10.6% at the second-stage stator and 2.8% at R2 as the AG decreases. The total-to-total efficiencies of the overall turbine increase by 0.306% and 0.295% when the AG decreases.

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