Performance of a Nozzle Guide Vane in Subsonic and Transonic Regimes Tested in an Annular Sector

2010 ◽  
Author(s):  
Tolga Yasa ◽  
Guillermo Paniagua ◽  
Jens Fridh ◽  
Damian Vogt
Keyword(s):  
Total Pressure ◽  
Guide Vane ◽  
Pressure Probe ◽  
Main Stream ◽  
Flow Angle ◽  
Nozzle Guide Vane ◽  
Annular Sector ◽  
Resistive Transducer ◽  
Institute Of Technology ◽  
Nozzle Guide

The understanding of shock interactions and mixing phenomena is crucial to design and analysis of advanced turbines. A nozzle guide vane (NGV) is experimentally investigated at subsonic and transonic off-design conditions (M2is of 0.6 and 0.95) in an annular sector at the Royal Institute of Technology (KTH). The effect of cooling ejection (3% of main stream mass flow rate) on the downstream flow field is also studied. The airfoil loading is monitored with pneumatic taps. The downstream pressure field is characterized at four different axial locations using a 5-hole probe and a total pressure probe that contains a single piezo-resistive transducer. The probe with a piezo resistive transducer is also used as a virtual 3-hole probe to measure the flow angle. The time-averaged yaw angle measured with the virtual 3-hole probe is in agreement with the 5-hole probe data. At subsonic conditions the wake causes a pressure loss of 7% of the upstream total pressure and covers 25% of the pitch whereas the pressure deficit is doubled in transonic operation. The coolant ejection results in an additional loss of 2% of the upstream total pressure. The flow speed does not have a significant effect on the wake width at 7% Cax. However, the low pressure region has different width at far downstream depending on the flow velocity. The fillet at the hub region has a significant effect on the secondary flow development. The frequency spectrums at the different conditions clearly reveal the shear layers. The results aim to help the characterization of mixing phenomena downstream of the NGV.

Some Aspects of Wake-Wake Interactions Regarding Turbine Stator Clocking

2000 ◽  
Vol 123 (3) ◽  
pp. 526-533 ◽  
Author(s):  
Maik Tiedemann ◽  
Friedrich Kost
Keyword(s):  
Total Pressure ◽  
Guide Vane ◽  
Pressure Fluctuations ◽  
Fast Response ◽  
Turbine Stage ◽  
Flow Angle ◽  
Wake Interactions ◽  
Turbulence Data ◽  
Number Flow ◽  
Nozzle Guide

This investigation is aimed at an experimental determination of the unsteady flowfield downstream of a transonic high pressure turbine stage. The single stage measurements, which were part of a joined European project, were conducted in the windtunnel for rotating cascades of the DLR Go¨ttingen. Laser-2-focus (L2F) measurements were carried out in order to determine the Mach number, flow angle, and turbulence distributions. Furthermore, a fast response pitot probe was utilized to determine the total pressure distribution. The measurement position for both systems was 0.5 axial rotor chord downstream of the rotor trailing edge at midspan. While the measurement position remained fixed, the nozzle guide vane (NGV) was “clocked” to 12 positions covering one NGV pitch. The periodic fluctuations of the total pressure downstream of the turbine stage indicate that the NGV wake damps the total pressure fluctuations caused by the rotor wakes. Furthermore, the random fluctuations are significantly lower in the NGV wake affected region. Similar conclusions were drawn from the L2F turbulence data. Since the location of the interaction between NGV wake and rotor wake is determined by the NGV position, the described effects are potential causes for the benefits of “stator clocking” which have been observed by many researchers.

Aerothermal Performance of Shielded Vane Design

2017 ◽  
Vol 139 (11) ◽  
Author(s):  
Ioanna Aslanidou ◽  
Budimir Rosic
Keyword(s):  
Heat Transfer ◽  
Total Pressure ◽  
High Speed ◽  
Guide Vane ◽  
Leading Edge ◽  
Experimental Facility ◽  
Numerical Studies ◽  
Nozzle Guide Vane ◽  
Inlet Conditions ◽  
Nozzle Guide

This paper presents an experimental investigation of the concept of using the combustor transition duct wall to shield the nozzle guide vane leading edge. The new vane is tested in a high-speed experimental facility, demonstrating the improved aerodynamic and thermal performance of the shielded vane. The new design is shown to have a lower average total pressure loss than the original vane, and the heat transfer on the vane surface is overall reduced. The peak heat transfer on the vane leading edge–endwall junction is moved further upstream, to a region that can be effectively cooled as shown in previously published numerical studies. Experimental results under engine-representative inlet conditions showed that the better performance of the shielded vane is maintained under a variety of inlet conditions.

Influence of the Gas-to-Wall Temperature Ratio on the Boundary Layer Transition: Investigation of the Wake Behind a Turbine Nozzle Guide Vane

2019 ◽  
Author(s):  
Pietro Formisano ◽  
Tânia S. Cação Ferreira ◽  
Tony Arts
Keyword(s):  
Wall Temperature ◽  
Total Pressure ◽  
Guide Vane ◽  
Boundary Layer Transition ◽  
Upstream Region ◽  
Bypass Transition ◽  
Temperature Ratio ◽  
Layer Transition ◽  
Nozzle Guide Vane ◽  
Nozzle Guide

Abstract Previous investigations performed at the von Karman Institute for Fluid Dynamics (VKI) have shown an influence of the gas-to-wall temperature ratio on the bypass transition development along the VKI LS89 blade suction side. In the present work, the influence of this quantity on the flow field downstream of this highly-loaded nozzle guide vane is studied through the evaluation of the aerodynamic losses. The investigation is organized in three sections with different combinations of exit Mach numbers and freestream turbulence intensity (FSTI) while Tgas/Twall is varied between 1.1 and 1.3 for all the tests. The Isentropic Compression Tube facility (CT-2) at VKI allowed the determination of the total pressure loss across the cascade by means of a Pitot tube in the upstream region and a downstream three-hole needle probe. The latter is traversed in the pitch-wise direction by a pneumatic traversing system. Finally, the cascade aerodynamic efficiency is quantified by means of the kinetic energy loss coefficient ζ and the total pressure drop profile distortions in the wake region.

scholarly journals Efficiency Measurements of an Annular Nozzle Guide Vane Cascade With Different Film Cooling Geometries

1998 ◽  
Author(s):  
Charles R. B. Day ◽  
Martin L. G. Oldfield ◽  
Gary D. Lock ◽  
Stephen N. Dancer
Keyword(s):  
Film Cooling ◽  
Total Pressure ◽  
Guide Vane ◽  
Cumulative Effect ◽  
Aerodynamic Efficiency ◽  
Nozzle Guide Vane ◽  
Density Ratios ◽  
Nozzle Guide ◽  
Annular Cascade ◽  
Nozzle Guide Vanes

This paper further extends the research reported by Day et al. (1997), which reported aerodynamic efficiency measurements on an annular cascade of engine representative transonic nozzle guide vanes with extensive film cooling. This work compares the measured aerodynamic efficiencies of blades with 14 rows of cylindrical cooling holes with a new geometry in which 8 of the rows have been replaced by holes having a fan-shaped exit geometry. The effects of adding trailing edge slot ejection are also presented. By selectively blocking rows of holes, the cumulative effect on the mid-span efficiency of adding rows of cooling holes has also been determined. A dense foreign gas (SF6/Ar mixture) is used to simulate engine representative coolant-to-mainstream density ratios, momentum ratios and blowing rates under ambient temperature conditions. The flowfield measurements have been obtained using a four-hole pyramid probe in a short duration blowdown facility which correctly models engine Reynolds and Mach numbers, as well as the inlet turbulence intensity. Experimental results are presented as area traverse maps (total pressure, isentropic Mach number and flow angles), from which the incremental changes in efficiency due to film cooling have been calculated. The effects of different assumptions for the coolant total pressure are shown. Experimental data agrees reasonably well with loss predictions using a Hartsel model.

A Computational Validation of Turbine Nozzle Guide Vane Aerodynamic Experiments in an HP Turbine Stage

2011 ◽  
Author(s):  
O¨zhan H. Turgut ◽  
Cengiz Camcı
Keyword(s):  
Validation Study ◽  
Total Pressure ◽  
Guide Vane ◽  
Pressure Coefficient ◽  
Axial Flow ◽  
Turbine Stage ◽  
Aerodynamic Loss ◽  
Nozzle Guide Vane ◽  
Nozzle Guide ◽  
Computational Validation

A computational validation study related to aerodynamic loss generation mechanisms is performed in an axial flow turbine nozzle guide vane (NGV). The 91.66 cm diameter axial flow turbine research facility has a stationary nozzle guide vane assembly and a 29 bladed HP turbine rotor. The NGV inlet and exit Reynolds numbers based on midspan axial chord are around 300000 and 900000, respectively. The effect of grid structure on aerodynamic loss generation is investigated. GAMBIT and TGRID combination is used for unstructured grid, whereas GRIDPRO is the structured grid generator. For both cases, y+ values are kept below unity. The finite-volume flow solver ANSYS CFX with SST k–ω turbulence model is employed. Experimental flow conditions are imposed at the boundaries. The flow transition effect and the influence of corner fillets at the vane-endwall junction are also studied in this paper. Grid independence study is performed with static pressure coefficient distribution at the mid-span of the vane and the total pressure coefficient at the NGV exit. The velocity distributions and the total pressure coefficient at the NGV exit plane are in very good agreement with the experimental data. This validation study shows that the effect of future geometrical modifications on the endwalls and the vane will be predicted reasonably accurately. The current study shows that an accurately measured turbine stage geometry, a properly prepared block structured/body fitted grid, a state of the art transitional flow implementation, and realistic boundary conditions coming from high resolution turbine experiments are all essential ingredients of a successful NGV aerodynamic loss quantification via computations.

Shower Head and Trailing Edge Cooling Influence on Transonic Vane Aero Performance

2014 ◽  
Vol 136 (11) ◽  
Author(s):  
Ranjan Saha ◽  
Jens Fridh ◽  
Torsten H. Fransson ◽  
Boris I. Mamaev ◽  
Mats Annerfeldt ◽  
...  
Keyword(s):  
Film Cooling ◽  
Guide Vane ◽  
Trailing Edge ◽  
Aerodynamic Loss ◽  
Nozzle Guide Vane ◽  
Turbine Vane ◽  
Engine Component ◽  
Annular Sector ◽  
Exit Mach Number ◽  
Nozzle Guide

An experimental investigation on a cooled nozzle guide vane (NGV) has been conducted in an annular sector to quantify aerodynamic influences of shower head (SH) and trailing edge (TE) cooling. The investigated vane is a typical high pressure gas turbine vane, geometrically similar to a real engine component, operated at a reference exit Mach number of 0.89. The investigations have been performed for various coolant-to-mainstream mass–flux ratios. New loss equations are derived and implemented regarding coolant aerodynamic losses. Results lead to a conclusion that both TE cooling and SH film cooling increase the aerodynamic loss compared to an uncooled case. In addition, the TE cooling has higher aerodynamic loss compared to the SH cooling. Secondary losses decrease with inserting SH film cooling compared to the uncooled case. The TE cooling appears to have less impact on the secondary loss compared to the SH cooling. Area-averaged exit flow angles around midspan increase for the TE cooling.

Shower Head and Trailing Edge Cooling Influence on Transonic Vane Aero Performance

2014 ◽  
Author(s):  
Ranjan Saha ◽  
Jens Fridh ◽  
Torsten H. Fransson ◽  
Boris I. Mamaev ◽  
Mats Annerfeldt ◽  
...  
Keyword(s):  
Film Cooling ◽  
Guide Vane ◽  
Trailing Edge ◽  
Aerodynamic Loss ◽  
Head Cooling ◽  
Nozzle Guide Vane ◽  
Turbine Vane ◽  
Annular Sector ◽  
Exit Mach Number ◽  
Nozzle Guide

An experimental investigation on a cooled nozzle guide vane has been conducted in an annular sector to quantify aerodynamic influences of shower head and trailing edge cooling. The investigated vane is a typical high pressure gas turbine vane, geometrically similar to a real engine component, operated at a reference exit Mach number of 0.89. The investigations have been performed for various coolant-to-mainstream mass-flux ratios. New loss equations are derived and implemented regarding coolant aerodynamic losses. Results lead to a conclusion that both trailing edge cooling and shower head film cooling increase the aerodynamic loss compared to an uncooled case. In addition, the trailing edge cooling has higher aerodynamic loss compared to the shower head cooling. Secondary losses decrease with inserting shower head film cooling compared to the uncooled case. The trailing edge cooling appears to have less impact on the secondary loss compared to the shower head cooling. Area-averaged exit flow angles around midspan increase for the trailing edge cooling.

Factors Influencing Computational Predictability of Aerodynamic Losses in a Turbine Nozzle Guide Vane Flow

2016 ◽  
Vol 138 (5) ◽  
Author(s):  
Özhan H. Turgut ◽  
Cengiz Camci
Keyword(s):  
Validation Study ◽  
Total Pressure ◽  
Guide Vane ◽  
Pressure Coefficient ◽  
Transitional Flow ◽  
Turbine Stage ◽  
Aerodynamic Loss ◽  
Nozzle Guide Vane ◽  
Nozzle Guide ◽  
Aerodynamic Losses

This paper deals with the computational predictability of aerodynamic losses in a turbine nozzle guide vane (NGV) flow. The paper shows that three-dimensional (3D) computations of Reynolds-Averaged Navier Stokes (RANS) equations have the ability to adequately represent viscous losses in the presence of laminar flows, transitional regions, and fully turbulent flow areas in the NGV of an high pressure (HP) turbine stage. The Axial Flow Turbine Research Facility (AFTRF) used for the present experimental results has an annular NGV assembly and a 29-bladed HP turbine rotor spinning at 1330 rpm. The NGV inlet and exit Reynolds numbers based on midspan axial chord are around 300,000 and 900,000, respectively. A general purpose finite-volume 3D flow solver with a shear stress transport (SST) k–ω turbulence model is employed. The current computational study benefits from these carefully executed aerodynamic experiments in the NGV of the AFTRF. The grid independence study is performed with static pressure coefficient distribution at the midspan of the vane and the total pressure coefficient at the NGV exit. The effect of grid structure on aerodynamic loss generation is emphasized. The flow transition effect and the influence of corner fillets at the vane–endwall junction are also studied. The velocity distributions and the total pressure coefficient at the NGV exit plane are in very good agreement with the experimental data. This validation study shows that the effect of future geometrical modifications on the turbine endwall surfaces will be predicted reasonably accurately. The current study also indicates that an accurately defined turbine stage geometry, a properly prepared block-structured/body-fitted grid, a state-of-the-art transitional flow implementation, inclusion of fillets, and realistic boundary conditions coming from high-resolution turbine experiments are all essential ingredients of a successful turbine NGV aerodynamic loss quantification via computations. This validation study forms the basis for the successful future generation of nonaxisymmetric endwall surface modifications in AFTRF research efforts.

scholarly journals Influence of Swirl Clocking on the Performance of Turbine Stage with Three-Dimensional Nozzle Guide Vane

Energies ◽  
2021 ◽  
Vol 14 (17) ◽  
pp. 5503
Author(s):  
Shinyoung Jeon ◽  
Changmin Son ◽  
Jinuk Kim
Keyword(s):  
Guide Vane ◽  
Influencing Factor ◽  
Three Dimensional ◽  
Leading Edge ◽  
Aerodynamic Performance ◽  
Flow Angle ◽  
Nozzle Guide Vane ◽  
Nozzle Guide ◽  
Relationship Of ◽  
The Relationship

The effect of the swirl clocking on three-dimensional nozzle guide vane (NGV) is investigated using computational fluid dynamics. The research reports the loss characteristics of leaned and swept NGVs and the influence of swirl clocking. The three-dimensional NGVs are built by stacking the same 2D profile along different linear axes, characterized by different angles with respect to the normal or radial direction: ε = −12° ~ +12° for the leaned and γ = −5° ~ +10° for the swept airfoils. A total of 40 models are analyzed to study the effects of lean and sweep on aerodynamic performance. To investigate the influence of swirl clocking, the analysis cases include the center of the swirl that was positioned at the leading edge as well as the middle of the passage. The prediction results show that the relationship of the changes in mass flow rate and throat area are not monotonic. Further observation confirms the redistribution of loading and flow angle under different lean and sweep angles; thus, three-dimensional design is a key influencing factor on aerodynamic performance. In the presence of swirl clocking, NGV performance is changed significantly and the findings offer new insight and opportunities to improve three-dimensional NGV airfoil design.

Experimental Study of the Flow Field Behind an Annular Turbine Nozzle Guide Vane With and Without Downstream Rotor

1984 ◽  
Author(s):  
E. Boletis ◽  
C. H. Sieverding
Keyword(s):  
Flow Field ◽  
Guide Vane ◽  
Three Dimensional ◽  
Rotor Blades ◽  
Pressure Probe ◽  
Flow Conditions ◽  
Nozzle Guide Vane ◽  
Contour Plots ◽  
Real Flow ◽  
Nozzle Guide

Measurements of the three dimensional flow field in annular turbine nozzle guide vanes present an important step in the simulation of the real flow conditions in turbomachinery bladings. This paper seeks to determine whether the installation of a rotor closely behind a high hub-to-tip ratio cascade (DH/DT=0.8) is indispensable for establishing correct flow conditions at the cascade exit or whether the use of an axial diffuser of a certain length is sufficient. Also, an attempt is made to separate the possible effects of the rotor blades from that of the rotating rotor disc. The tests are carried out on a low speed, low aspect ratio, high turning nozzle guide vane. The flow is explored by means of a double head four-hole pressure probe and the results are presented in the form of contour plots and spanwise pitch-averaged distributions of losses, flow angles and static pressure.

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