Influence of Upstream Flow Conditions on the Heat Transfer to Nozzle Guide Vanes

1988 ◽  
Vol 110 (3) ◽  
pp. 412-416 ◽  
Author(s):  
V. Krishnamoorthy ◽  
B. R. Pai ◽  
S. P. Sukhatme
Keyword(s):  
Guide Vane ◽  
Gas Temperature ◽  
Flow Conditions ◽  
Cold Flow ◽  
Hot Gas ◽  
Nozzle Guide Vane ◽  
High Turbulence ◽  
Nozzle Guide ◽  
Nozzle Guide Vanes ◽  
Upstream Flow

The influence of a combustor located just upstream of a nozzle guide vane cascade on the heat flux distribution to the nozzle guide vane was experimentally investigated. The surface temperature distribution around the convectively cooled vane of the cascade was obtained by locating the cascade, firstly in a low-turbulence uniform hot gas stream, secondly in a high-turbulence, uniform hot gas stream, and thirdly in a high-turbulence, nonuniform hot gas stream present just downstream of the combustor exit. The results indicate that the increased blade surface temperatures observed for the cascade placed just downstream of the combustor can be accounted for by the prevailing turbulence level measured at cascade inlet in cold-flow conditions and the average gas temperature at the cascade inlet.

The Effects of High Mainstream Turbulence and Turbine Vane Film Cooling on the Dispersion of a Simulated Hot Streak

2003 ◽  
Author(s):  
Sean Jenkins ◽  
Krishnakumar Varadarajam ◽  
David G. Bogard
Keyword(s):  
Film Cooling ◽  
Guide Vane ◽  
Suction Side ◽  
Peak Temperature ◽  
Nozzle Guide Vane ◽  
Turbulence Effects ◽  
High Turbulence ◽  
Nozzle Guide ◽  
Hot Streak ◽  
Film Cooling Holes

This paper presents the combined effects of high turbulence and film cooling on the dispersion of a simulated hot streak as it passes over a scaled-up nozzle guide vane. Experimental data demonstrates a considerable decay in the strength of a hot streak due to turbulence effects alone. Film cooling further reduces the peak temperature values resulting in a reduction of the peak temperature in the hot streak on the order of 75% relative to the upstream peak temperature in the hot streak. Comparisons are made between high turbulence (Tu = 20%) and moderate turbulence (Tu = 3.5%) as well as between different blowing conditions for the suction side, showerhead, and pressure side film cooling holes on a simulated nozzle guide vane.

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.

The Influence of the Boundary Layer State and Reynolds Number on Film Cooling and Heat Transfer on a Cooled Nozzle Guide Vane

2000 ◽  
Author(s):  
Hans Reiss ◽  
Albin Bölcs
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Film Cooling ◽  
Guide Vane ◽  
Suction Side ◽  
Flow Conditions ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
Nozzle Guide Vane ◽  
Nozzle Guide

Film cooling and heat transfer measurements were carried out on a cooled nozzle guide vane in a linear cascade, using a transient liquid crystal technique. Three flow conditions were realized: the nominal operating condition of the vane with an exit Reynolds number of 1.47e6, as well as two lower flow conditions: Re2L = 1.0e6 and 7.5e5. The vane model was equipped with a single row of inclined round film cooling holes with compound angle orientation on the suction side. Blowing ratios ranging form 0.3 to 1.5 were covered, all using foreign gas injection (CO2) yielding an engine-representative density ratio of 1.6. Two distinct states of the incoming boundary layer onto the injection station were compared, an undisturbed laminar boundary layer as it forms naturally on the suction side, and a fully turbulent boundary layer which was triggered with a trip wire upstream of injection. The aerodynamic flow field is characterized in terms of profile Mach number distribution, and the associated heat transfer coefficients around the uncooled airfoil are presented. Both detailed and spanwise averaged results of film cooling effectiveness and heat transfer coefficients are shown on the suction side, which indicate considerable influence of the state of the incoming boundary layer on the performance of a film cooling row. The influence of the mainstream flow condition on the film cooling behavior at constant blowing ratio is discussed for three chosen injection regimes.

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.

Effects of Gap Leakage on Fluid Flow in a Contoured Turbine Nozzle Guide Vane

2000 ◽  
Author(s):  
Y.-L. Lin ◽  
T. I-P. Shih ◽  
M. K. Chyu ◽  
R. S. Bunker
Keyword(s):  
Computational Study ◽  
Guide Vane ◽  
Three Dimensional ◽  
Secondary Flows ◽  
Navier Stokes ◽  
Hot Gas ◽  
Nozzle Guide Vane ◽  
A Cell ◽  
Nozzle Guide ◽  
Volume Method

Computations were performed to study the three-dimensional flow in a nozzle guide vane with leakage issuing from a narrow gap with a backward-facing step located upstream of the airfoil on each endwall. The nozzle guide vane investigated has one flat and one contoured endwall. For the contoured endwall, two configurations of the same contouring profile were investigated with and without gap leakage. In one configuration, all contouring is upstream of the airfoil passage. In the other, the contouring starts upstream of the airfoil passage and continues through it. Results obtained show that when there is gap leakage, secondary flows are reduced at all endwalls for both nozzle configurations investigated. Without gap leakage, secondary flows are reduced only on the contoured endwall in which the contouring started upstream of the airfoil passage and continued through it. When all of the contouring is located upstream of the airfoil passage, there is considerable hot gas ingestion into the gap at both endwalls. When the contouring starts upstream of the airfoil passage and continues throught it, hot gas ingestion was minimal at the contoured endwall and greatly reduced at the flat endwall. This computational study is based on the ensemble-averaged conservation equations of mass, momentum (compressible Navier-Stokes), and energy. Effects of turbulence were modeled by the low Reynolds number shear-stress transport k-ω model. Solutions were generated by a cell-centered finite-volume method that uses third-order accurate flux-difference splitting of Roe with limiters and multigrid acceleration of a diagonalized ADI scheme with local time stepping on patched structured grids.

Experimental Evaluation of Service-Exposed Nozzle Guide Vane Damage in a Rolls Royce A-250 Gas Turbine

2013 ◽  
Author(s):  
D. Bouchard ◽  
A. Asghar ◽  
M. LaViolette ◽  
W. D. E. Allan ◽  
R. Woodason
Keyword(s):  
Performance Metrics ◽  
Guide Vane ◽  
Trailing Edge ◽  
Root Area ◽  
Trailing Edges ◽  
Nozzle Guide Vane ◽  
Nozzle Guide ◽  
Edge Damage ◽  
Annular Cascade ◽  
Nozzle Guide Vanes

A unique methodology and test rig was designed to evaluate the degradation of damaged Nozzle Guide Vanes in a transonic annular cascade in the short duration facility at the Royal Military College. A custom test section was designed which featured a novel rotating instrumentation suite. This permitted 360° multi-span traverse measurements downstream of unmodified turbine NGV rings from a Rolls-Royce/Allison A-250 turbo-shaft engine. Downstream total pressure was measured at four span-wise locations on both an undamaged reference and a damaged test article. Three performance metrics were developed in an effort to determine characteristic signatures for common operational damage such as trailing edge bends or cracked trailing edges. The highest average losses were observed in the root area, while the lowest occurred closer to the NGV tips. The results from this study indicated that multiple span-wise traverses were required to detect localized trailing edge damage. Recommendations have been made for future tests, for test rigs and for ideas to develop performance metrics.

The Effects of High Mainstream Turbulence and Turbine Vane Film Cooling on the Dispersion of a Simulated Hot Streak

2004 ◽  
Vol 126 (1) ◽  
pp. 203-211 ◽  
Author(s):  
Sean Jenkins ◽  
Krishnakumar Varadarajan ◽  
David G. Bogard
Keyword(s):  
Film Cooling ◽  
Guide Vane ◽  
Suction Side ◽  
Peak Temperature ◽  
Nozzle Guide Vane ◽  
Turbulence Effects ◽  
High Turbulence ◽  
Nozzle Guide ◽  
Hot Streak ◽  
Film Cooling Holes

This paper presents the combined effects of high turbulence and film cooling on the dispersion of a simulated hot streak as it passes over a scaled-up nozzle guide vane. Experimental data demonstrates a considerable decay in the strength of a hot streak due to turbulence effects alone. Film cooling further reduces the peak temperature values resulting in a reduction of the peak temperature in the hot streak on the order of 75% relative to the upstream peak temperature in the hot streak. Comparisons are made between high turbulence Tu=20% and moderate turbulence Tu=3.5% as well as between different blowing conditions for the suction side, showerhead, and pressure side film cooling holes on a simulated nozzle guide vane.

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.

Experimental Evaluation of Service-Exposed Nozzle Guide Vane Damage in a Rolls Royce A-250 Gas Turbine

2014 ◽  
Vol 136 (10) ◽  
Author(s):  
D. Bouchard ◽  
A. Asghar ◽  
M. LaViolette ◽  
W. D. E. Allan ◽  
R. Woodason
Keyword(s):  
Performance Metrics ◽  
Guide Vane ◽  
Trailing Edge ◽  
Root Area ◽  
Trailing Edges ◽  
Nozzle Guide Vane ◽  
Nozzle Guide ◽  
Edge Damage ◽  
Annular Cascade ◽  
Nozzle Guide Vanes

A unique methodology and test rig was designed to evaluate the degradation of damaged nozzle guide vanes (NGVs) in a transonic annular cascade in the short duration facility at the Royal Military College. A custom test section was designed which featured a novel rotating instrumentation suite. This permitted 360 deg multispan traverse measurements downstream from unmodified turbine NGV rings from a Rolls-Royce/Allison A-250 turbo-shaft engine. The downstream total pressure was measured at four spanwise locations on both an undamaged reference and a damaged test article. Three performance metrics were developed in an effort to determine characteristic signatures for common operational damage such as trailing edge bends or cracked trailing edges. The highest average losses were observed in the root area, while the lowest occurred closer to the NGV tips. The results from this study indicated that multiple spanwise traverses were required to detect localized trailing edge damage. Recommendations are made for future testing and to further develop performance metrics.

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