scholarly journals Secondary Flow Reduction in a Nozzle Guide Vane Cascade by Non-Axisymmetric End-Wall Profiling

1999 ◽  
Author(s):  
J. Yan ◽  
D. G. Gregory-Smith ◽  
P. J. Walker
Keyword(s):  
Secondary Flow ◽  
Static Pressure ◽  
Guide Vane ◽  
Suction Surface ◽  
Linear Cascade ◽  
Pressure Surface ◽  
Nozzle Guide Vane ◽  
Nozzle Guide ◽  
Nozzle Guide Vanes ◽  
End Wall

A linear cascade of HP steam turbine nozzle guide vanes was designed and built in order to study the effect of a non-axisymmetric profile for the endwall. The profile was designed by using CFD for the purpose of reducing the secondary flow. The method was to use convex curvature near the pressure surface to reduce the static pressure and concave curvature near the suction surface to increase it. Thus the cross passage pressure gradient which drives the secondary flow would be reduced. Detailed investigations of the flow field with a flat end-wall and the profiled end-wall were conducted. The effect of the profiled end-wall on the secondary flow development was determined and also compared with the CFD design predictions. It was found that the secondary loss and secondary kinetic energy were both reduced by about 20% with the shaped endwall, and a more uniform exit flow was also achieved.

Nozzle Passage Endwall Effectiveness Values With Various Combustor Coolant Flowrates—Part 2: Endwall and Vicinity Surface Effectiveness Measurements

2021 ◽  
Vol 143 (4) ◽  
Author(s):  
Kedar P. Nawathe ◽  
Rui Zhu ◽  
Enci Lin ◽  
Yong W. Kim ◽  
Terrence W. Simon
Keyword(s):  
Gas Turbines ◽  
Guide Vane ◽  
Suction Surface ◽  
Turbine Engine ◽  
Pressure Surface ◽  
Coolant Injection ◽  
Measurement Results ◽  
Nozzle Guide Vane ◽  
Effectiveness Measurement ◽  
Nozzle Guide

Abstract Effective coolant schemes are required for providing cooling to the first-stage stator vanes of gas turbines. To correctly predict coolant performance on the endwall and vane surfaces, these coolant schemes should also consider the effects of coolant streams introduced upstream in the combustor section of a gas turbine engine. This two-part paper presents measurements taken on a first-stage nozzle guide vane cascade that includes combustor coolant injection. The first part of this paper explains how coolant transport and coolant-mainstream interaction in the vane passage is affected by changing the combustor coolant and endwall film coolant flowrates. This paper explains how those flows affect the coolant effectiveness on the endwall and vane surfaces. Part one showed that a significant amount of coolant injected upstream of the endwall is present along the pressure surface of the vanes as well as over the endwall. Part two shows effectiveness measurement results taken in this study on the endwall and pressure and suction surfaces of the vanes. Sustained endwall coolant effectiveness is observed along the whole passage for all cases. It is uniform in the pitch-wise direction. Combustor coolant flow significantly affects cooling performance even near the trailing edge. The modified flowfield results in the pressure surface being cooled more effectively than the suction surface. While the effectiveness distribution on the pressure surface varies with combustor and film coolant flowrates, the distribution along the suction surface remains largely unchanged.

Temperature Effects on Nozzle Guide Vane Deposition in a New Turbine Cascade Rig

2016 ◽  
Author(s):  
Ryan Lundgreen ◽  
Craig Sacco ◽  
Robin Prenter ◽  
Jeffrey P. Bons
Keyword(s):  
Guide Vane ◽  
Turbine Engines ◽  
Turbine Cascade ◽  
Stagnation Line ◽  
Pressure Surface ◽  
Nozzle Guide Vane ◽  
First Results ◽  
Inlet Conditions ◽  
Nozzle Guide ◽  
Nozzle Guide Vanes

A new turbine cascade has been constructed that is designed to investigate the performance of actual nozzle guide vane hardware at temperatures representative of modern gas turbine engines. The facility is designed to investigate internal and external deposition, analyze the effectiveness of new cooling techniques, characterize material systems such as metal substrates or coatings, and assess the aerodynamic performance of a vane. The results presented here are the first results obtained in this new facility. External deposition on cooled CFM56 nozzle guide vanes has been explored at inlet temperatures of 1090° C, 1265° C, and 1350° C. Results at 1090° C have been compared to similar results in a previous facility. External deposition tests at temperatures greater than 1100° C on actual turbine hardware have not been reported publicly prior to this paper. These results show that deposition is concentrated at the stagnation line at all three inlet conditions. The amount of deposition on the vane pressure surface increased with increasing inlet temperatures.

Heat Transfer and Aerodynamics of a High Rim Speed Turbine Nozzle Guide Vane With Profiled End Walls

1992 ◽  
Author(s):  
K. S. Chana
Keyword(s):  
Heat Transfer ◽  
Mach Number ◽  
Guide Vane ◽  
Secondary Flows ◽  
Test Facility ◽  
Suction Surface ◽  
Flow And Heat Transfer ◽  
Nozzle Guide Vane ◽  
Nozzle Guide ◽  
Nozzle Guide Vanes

It has been shown that the secondary flows present within turbine nozzle guide vanes have a marked effect on heat transfer. The horse-shoe and passage vortices, for example, have a major impact on platform and vane suction surface heat transfer. To investigate these effects further, heat transfer and aerodynamic measurements have been made on an annular transonic turbine nozzle guide vane ring, with three different platform geometries. The measurements were taken in the Isentropic Light Piston test facility at RAE Pyestock at representative values of engine Reynolds number, Mach number and freestream gas-to-wall temperature ratio. This paper compares and discusses the measured platform and vane suction surface Nusselt and Mach number distributions for the three different endwall profiles. Comparisons with theoretical flow and heat transfer predictions are presented.

A Simple Procedure to Reduce Secondary Flow Effect in Turbine Nozzle Guide Vanes

2007 ◽  
Author(s):  
Bao Q. Nguyen ◽  
Kyle D. Squires
Keyword(s):  
Secondary Flow ◽  
Turbine Blade ◽  
Guide Vane ◽  
Simple Procedure ◽  
Simple Method ◽  
Flow Effect ◽  
Nozzle Guide Vane ◽  
Nozzle Guide ◽  
End Wall ◽  
Wall Geometry

Secondary flow contributes about one-third of the total loss in turbine nozzle. Although secondary flow characteristics are well understood, it is still a challenge to mitigate the secondary flow effect. Several methods have been proposed to reduce secondary flow loss in turbine blade rows. They include: blade 3D stacking, blade 3D design, and end wall contouring, either axisymmetric and non-axisymmetric. The latter approach produces fully 3D end wall geometry, in contrast to the conventional axisymmetric shape. Several authors have applied elaborated procedure to adjust the end wall geometry of turbine blade rows. In this paper, we present a simple method to modify the hub wall of a turbine nozzle guide vane row with a single function. This function requires 2 geometry parameters which are established by CFD. The numerical results for a high work turbine nozzle guide vane show that a reduction in secondary kinetic energy is possible.

Aero-Thermal Performance of a Two-Dimensional Highly Loaded Transonic Turbine Nozzle Guide Vane: A Test Case for Inviscid and Viscous Flow Computations

1992 ◽  
Vol 114 (1) ◽  
pp. 147-154 ◽  
Author(s):  
T. Arts ◽  
M. Lambert de Rouvroit
Keyword(s):  
Heat Transfer ◽  
Turbulence Intensity ◽  
Static Pressure ◽  
Free Stream ◽  
Guide Vane ◽  
Free Stream Turbulence ◽  
Nozzle Guide Vane ◽  
Transonic Turbine ◽  
Nozzle Guide ◽  
Highly Loaded

This contribution deals with an experimental aero-thermal investigation around a highly loaded transonic turbine nozzle guide vane mounted in a linear cascade arrangement. The measurements were performed in the von Karman Institute short duration Isentropic Light Piston Compression Tube facility allowing a correct simulation of Mach and Reynolds numbers as well as of the gas to wall temperature ratio compared to the values currently observed in modern aero engines. The experimental program consisted of flow periodicity checks by means of wall static pressure measurements and Schlieren flow visualizations, blade velocity distribution measurements by means of static pressure tappings, blade convective heat transfer measurements by means of platinum thin films, downstream loss coefficient and exit flow angle determinations by using a new fast traversing mechanism, and free-stream turbulence intensity and spectrum measurements. These different measurements were performed for several combinations of the free-stream flow parameters looking at the relative effects on the aerodynamic blade performance and blade convective heat transfer of Mach number, Reynolds number, and free-stream turbulence intensity.

scholarly journals Aero-Thermal Performance of a Two Dimensional Highly Loaded Transonic Turbine Nozzle Guide Vane: A Test Case for Inviscid and Viscous Flow Computations

1990 ◽  
Author(s):  
Tony Arts ◽  
Muriel Lambert De Rouvroit
Keyword(s):  
Heat Transfer ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Turbulence Intensity ◽  
Static Pressure ◽  
Guide Vane ◽  
Nozzle Guide Vane ◽  
Transonic Turbine ◽  
Nozzle Guide ◽  
Highly Loaded

This contribution deals with an experimental aero-thermal investigation around a highly loaded transonic turbine nozzle guide vane mounted in a linear cascade arrangement. The measurements were performed in the von Karman Institute short duration Isentropic Light Piston Compression Tube facility allowing a correct simulation of Mach and Reynolds numbers as well as of the gas to wall temperature ratio compared to the values currently observed in modern aero engines. The experimental programme consisted of flow periodicity checks by means of wall static pressure measurements and Schlieren flow visualizations, blade velocity distribution measurements by means of static pressure tappings, blade convective heat transfer measurements by means of platinum thin films, downstream loss coefficient and exit flow angle determinations by using a new fast traversing mechanism and freestream turbulence intensity and spectrum measurements. These different measurements were performed for several combinations of the freestream flow parameters looking at the relative effects on the aerodynamic blade performance and blade convective heat transfer of Mach number, Reynolds number and freestream turbulence intensity.

Comparison of Film Cooling Performance for Different Purge Slot Configurations in a Cylindrical and State-of-the-Art Nozzle Guide Vane

2021 ◽  
Author(s):  
Christian Landfester ◽  
Gunther Müller ◽  
Robert Krewinkel ◽  
Clemens Domnick ◽  
Martin Böhle
Keyword(s):  
Secondary Flow ◽  
Film Cooling ◽  
State Of The Art ◽  
Guide Vane ◽  
High Pressure Turbine ◽  
Cooling Effectiveness ◽  
Cooling Performance ◽  
Film Cooling Effectiveness ◽  
Nozzle Guide Vane ◽  
Nozzle Guide

Abstract This comparative study is concerned with the advances in nozzle guide vane (NGV) design developments and their influence on the film cooling performance by injecting coolant through the purge slot. An experimental study compares the film cooling effectiveness as well as the aerodynamic effects for different purge slot configurations on both a flat and an axisymmetrically contoured endwall of a NGV. While the flat endwall cascade was equipped with four cylindrical vanes, the contoured endwall cascade consisted of four modern NGVs which represent state-of-the-art high-pressure turbine design standards. Geometric variations, e.g. the purge slot width and injection angle, as well as different blowing ratios (BR) at an engine-like density ratio (DR = 1.6) were realized to investigate the real-life effect of thermal expansion, design modifications and the interaction between secondary flow and coolant. The mainstream flow parameters were set to meet real engine conditions with regard to Reynolds and Mach numbers. The Pressure Sensitive Paint (PSP) technique was used to determine the adiabatic film cooling effectiveness. Five-hole probe measurements (DR = 1.0) were performed to measure the flow field with its characteristic vortex structures as well as the loss distribution in the vane wake region. For a more profound insight into the origin and development of the secondary flows, oil dye visualizations were carried out on both endwalls. The measurement results will be discussed based on a side-by-side comparison of the distribution of film cooling effectiveness on the endwall, its area-averaged values as well as the two-dimensional distribution of total pressure losses and the secondary flow field. The results of this study show that the advances in NGV design development have had a significantly positive influence on the distribution of the coolant. This has to be attributed to lesser disturbance of the coolant propagation by secondary flow for the optimized NGV design, since the design features are intended to suppress the formation of secondary flow. In contrast to the results of the cylindrical profile, sufficient cooling can be already provided with a perpendicular injection in the case of the modern NGV. It is therefore advisable to take these effects into account when designing the film cooling system of a modern high-pressure turbine.

Influence of Prehistory and Leading Edge Contouring on Aero Performance of a Three-Dimensional Nozzle Guide Vane

2014 ◽  
Vol 136 (7) ◽  
Author(s):  
Ranjan Saha ◽  
Boris I. Mamaev ◽  
Jens Fridh ◽  
Björn Laumert ◽  
Torsten H. Fransson
Keyword(s):  
Guide Vane ◽  
Three Dimensional ◽  
Leading Edge ◽  
Stagnation Line ◽  
Wide Range ◽  
Nozzle Guide Vane ◽  
Loss Coefficients ◽  
Exit Mach Number ◽  
Nozzle Guide ◽  
End Wall

Experiments are conducted to investigate the effect of the prehistory in the aerodynamic performance of a three-dimensional nozzle guide vane with a hub leading edge contouring. The performance is determined with two pneumatic probes (five hole and three hole) concentrating mainly on the end wall. The investigated vane is a geometrically similar gas turbine vane for the first stage with a reference exit Mach number of 0.9. Results are compared for the baseline and filleted cases for a wide range of operating exit Mach numbers from 0.5 to 0.9. The presented data includes loading distributions, loss distributions, fields of exit flow angles, velocity vector, and vorticity contour, as well as mass-averaged loss coefficients. The results show an insignificant influence of the leading edge fillet on the performance of the vane. However, the prehistory (inlet condition) affects significantly in the secondary loss. Additionally, an oil visualization technique yields information about the streamlines on the solid vane surface, which allows identifying the locations of secondary flow vortices, stagnation line, and saddle point.

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.

Full-Scale Vibration Testing of Nozzle Guide Vanes

2021 ◽  
Author(s):  
Giuseppe Macoretta ◽  
Bernardo Disma Monelli ◽  
Paolo Neri ◽  
Federico Bucciarelli ◽  
Damaso Checcacci ◽  
...  
Keyword(s):  
Thermal Loading ◽  
Guide Vane ◽  
Full Scale ◽  
Operational Flexibility ◽  
Additional Control ◽  
Partial Load ◽  
Nozzle Guide Vane ◽  
Stator Vane ◽  
Nozzle Guide ◽  
Nozzle Guide Vanes

Abstract An increasing number of turboexpanders are equipped with Nozzle Guide Vane (NGV) as the first stator stage. By varying the throat area of the first stator vane the NGV enables an additional control methodology to the line-up power output allowing higher operational flexibility and higher efficiency at partial load and partial speed. The design of this component might become critical for enabling high expander availability considering its exposure to high temperature, thermal loading, and fluid induced vibrations. This is especially true also considering that the vibration frequencies of this sub-assembly are influenced by internal clearances and by the value of the friction coefficient, which leaves a relevant margin of error when using numerical methods (such as FEM) for predicting the actual structural behavior of this component. In this paper, the design of a full-scale test bench for the determination of both friction coefficients and modal behavior of a nozzle guide vane geometry is described. The bench enables us to simulate the pre-load due to aerodynamic forces on the NGV airfoil simulating the actual working conditions of bushes and bearings.

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