Scaling of Guide Vane Coolant Profiles and the Reduction of a Simulated Hot Streak

2006 ◽  
Vol 129 (3) ◽  
pp. 619-627 ◽  
Author(s):  
Sean C. Jenkins ◽  
David G. Bogard
Keyword(s):  
Gas Flow ◽  
Elevated Temperatures ◽  
Guide Vane ◽  
High Heat ◽  
Stagnation Line ◽  
Turbine Engine ◽  
Scaling Methods ◽  
Nozzle Guide ◽  
Hot Streak ◽  
Heat Loads

The turbine section of a gas turbine engine is subjected to a nonuniform temperature distribution in the gas flow from the combustor. Regions of elevated temperatures, known as “hot streaks,” subject the turbine airfoil to high heat loads. In this study, the reduction of hot streaks by coolant from a film cooled nozzle guide vane was experimentally evaluated. Experiments were conducted with an approach mainstream turbulence level of 20% to simulate actual turbine conditions. The coolant distributions downstream of the vane were measured for varying blowing ratios and varying coolant density, and scaling methods were found for variations in both parameters. For this study, the hot streak peak was positioned to impact the vane at the stagnation line. Measurements of the hot streak strength with coolant blowing showed as much as a 55% decrease in peak temperature compared with no coolant.

Scaling of Guide Vane Coolant Profiles and the Reduction of a Simulated Hot Streak

2005 ◽  
Author(s):  
Sean C. Jenkins ◽  
David G. Bogard
Keyword(s):  
Gas Flow ◽  
Elevated Temperatures ◽  
Guide Vane ◽  
High Heat ◽  
Stagnation Line ◽  
Turbine Engine ◽  
Scaling Methods ◽  
Nozzle Guide ◽  
Hot Streak ◽  
Heat Loads

The turbine section of a gas turbine engine is subjected to a non-uniform temperature distribution in the gas flow from the combustor. Regions of elevated temperatures, known as “hot streaks,” subject the turbine airfoil to high heat loads. In this study, the reduction of hot streaks by coolant from a film cooled nozzle guide vane was experimentally evaluated. Experiments were conducted with an approach mainstream turbulence level of 20% to simulate actual turbine conditions. The coolant distributions downstream of the vane were measured for varying blowing ratios and varying coolant density, and scaling methods were found for variations in both parameters. For this study, the hot streak peak was positioned to impact the vane at the stagnation line. Measurements of the hot streak strength with coolant blowing showed as much as a 55% decrease in peak temperature compared with no coolant.

Superposition Predictions of the Reduction of Hot Streaks by Coolant From a Film-Cooled Guide Vane

2009 ◽  
Vol 131 (4) ◽  
Author(s):  
Sean C. Jenkins ◽  
David G. Bogard
Keyword(s):  
Guide Vane ◽  
Operating Conditions ◽  
Measured Temperature ◽  
Turbine Engine ◽  
Temperature Distributions ◽  
Superposition Technique ◽  
Pass Through ◽  
Nozzle Guide ◽  
Hot Streak ◽  
Nozzle Guide Vanes

The turbine section of a gas turbine engine is subjected to hot gases flowing from the combustor that typically have high temperature regions known as “hot streaks.” These hot streaks pass through the nozzle guide vanes, either impacting the vanes or passing through the passages between vanes. Generally the vanes are highly film cooled, and the coolant from the vanes interacts with the hot streak resulting in a reduction of the hot streak temperature. In this study, predictions of the reduction of hot streaks were made using superposition of measured temperature distributions due to coolant injection and measured temperature distributions of hot streaks. These predictions were compared to the measured hot streak reduction to determine the accuracy of the superposition technique. Results showed that the superposition predictions generally underpredicted the reduction of the peak hot streak temperature, but were within at least 20% of the peak temperature value. The superposition technique was also found to be useful for determining the hot streak reduction for different hot streak locations, and different coolant and hot streak operating conditions.

Superposition Predictions of the Reduction of Hot Streaks by Coolant From a Film Cooled Guide Vane

2005 ◽  
Author(s):  
Sean C. Jenkins ◽  
David G. Bogard
Keyword(s):  
Guide Vane ◽  
Operating Conditions ◽  
Measured Temperature ◽  
Turbine Engine ◽  
Temperature Distributions ◽  
Superposition Technique ◽  
Pass Through ◽  
Nozzle Guide ◽  
Hot Streak ◽  
Nozzle Guide Vanes

The turbine section of a gas turbine engine is subjected to hot gases flowing from the combustor that typically have high temperature regions known as “hot streaks.” These hot streaks pass through the nozzle guide vanes, either impacting the vanes or passing through the passages between vanes. Generally the vanes are highly film cooled, and the coolant from the vanes interacts with the hot streak resulting in a reduction of the hot streak temperature. In this study, predictions of the reduction of hot streaks were made using superposition of measured temperature distributions due to coolant injection and measured temperature distributions of hot streaks. These predictions were compared to the measured hot streak reduction to determine the accuracy of the superposition technique. Results showed that the superposition predictions generally underpredicted the reduction of the peak hot streak temperature, but were within at least 20% of the peak temperature value. The superposition technique was also found to be useful for determining the hot streak reduction for different hot streak locations, and different coolant and hot streak operating conditions.

Influence of Pre-History and Leading Edge Contouring on Aero-Performance of a 3D Nozzle Guide Vane

2013 ◽  
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 ◽  
Turbine Vane ◽  
Loss Coefficients ◽  
Exit Mach Number ◽  
Nozzle Guide

Experiments are conducted to investigate the effect of the pre-history 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 (5 hole and 3 hole) concentrating mainly on the endwall. 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 pre-history (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.

Flow Field Simulations of a Gas Turbine Combustor

2002 ◽  
Vol 124 (3) ◽  
pp. 508-516 ◽  
Author(s):  
M. D. Barringer ◽  
O. T. Richard ◽  
J. P. Walter ◽  
S. M. Stitzel ◽  
K. A. Thole
Keyword(s):  
Flow Field ◽  
Gas Turbine ◽  
Large Scale ◽  
Guide Vane ◽  
Wall Region ◽  
Turbine Engine ◽  
Tunnel Section ◽  
Nozzle Guide ◽  
Nozzle Guide Vanes ◽  
Combustor Liner

The flow field exiting the combustor in a gas turbine engine is quite complex considering the presence of large dilution jets and complicated cooling schemes for the combustor liner. For the most part, however, there has been a disconnect between the combustor and turbine when simulating the flow field that enters the nozzle guide vanes. To determine the effects of a representative combustor flow field on the nozzle guide vane, a large-scale wind tunnel section has been developed to simulate the flow conditions of a prototypical combustor. This paper presents experimental results of a combustor simulation with no downstream turbine section as a baseline for comparison to the case with a turbine vane. Results indicate that the dilution jets generate turbulence levels of 15–18% at the exit of the combustor with a length scale that closely matches that of the dilution hole diameter. The total pressure exiting the combustor in the near-wall region neither resembles a turbulent boundary layer nor is it completely uniform putting both of these commonly made assumptions into question.

Validation and Comparison of Strip Seal Designs for Gas Turbine Engine Nozzle Guide Vanes

2008 ◽  
Author(s):  
Arash Farahani ◽  
Peter Childs
Keyword(s):  
Gas Turbine ◽  
Guide Vane ◽  
Gas Turbine Engine ◽  
Experimental Comparison ◽  
Cfd Modelling ◽  
Guide Vanes ◽  
Turbine Engine ◽  
Seal Design ◽  
Nozzle Guide ◽  
Nozzle Guide Vanes

Strip seals are commonly used to prevent or limit leakage flows between nozzle guide vanes (NGV) and other gas turbine engine components that are assembled from individual segments. Leakage flow across, for example, a nozzle guide vane platform, leads to increased demands on the gas turbine engine internal flow system and a rise in specific fuel consumption (SFC). Careful attention to the flow characteristics of strip seals is therefore necessary. The very tight tolerances associated with strip seals provides a particular challenge to their characterisation. This paper reports the validation of CFD modelling for the case of a strip seal under very carefully controlled conditions. In addition, experimental comparison of three types of strip seal design, straight, arcuate, and cloth, is presented. These seals are typical of those used by competing manufacturers of gas turbine engines. The results show that the straight seal provides the best flow sealing performance for the controlled configuration tested, although each design has its specific merits for a particular application.

Influence of Hot Streak Circumferential Length-Scale in Transonic Turbine Stage

2004 ◽  
Author(s):  
L. He ◽  
V. Menshikova ◽  
B. R. Haller
Keyword(s):  
Heat Transfer ◽  
Computational Study ◽  
Guide Vane ◽  
Strong Dependence ◽  
Rotor Blades ◽  
Inlet Temperature ◽  
Turbine Stage ◽  
Blade Vibration ◽  
Nozzle Guide ◽  
Hot Streak

A computational study is carried out on the influence of turbine inlet temperature distortion (hot streak). The hot streak effects are examined from both aeromechanical (forced blade vibration) and aero-thermal (heat transfer) points of view. Computations are firstly carried out for a transonic HP turbine stage, and the steady and unsteady surface pressure results are compared with the corresponding experimental data. Subsequent analysis is carried out for hot-streaks with variable circumferential wavelength, corresponding to different numbers of combustion burners. The results show that the circumferential wavelength of the temperature distortion can significantly change unsteady forcing as well as the heat-transfer to rotor blades. In particular, when the hot-streak wavelength is the same as the nozzle guide vane (NGV) blade pitch, there is a strong dependence of the preferential heating characteristics on the relative clocking position between hot-streak and NGV blade. However, this clocking dependence is shown to be qualitatively weakened for the cases with fewer hot streaks with longer circumferential wavelengths.

Coal Ash Deposition on Nozzle Guide Vanes: Part I—Experimental Characteristics of Four Coal Ash Types

2011 ◽  
Author(s):  
J. Webb ◽  
B. Casaday ◽  
B. Barker ◽  
J. P. Bons ◽  
A. D. Gledhill ◽  
...  
Keyword(s):  
Film Cooling ◽  
Gas Flow ◽  
Guide Vane ◽  
Ambient Pressure ◽  
Coal Ash ◽  
Leading Edge ◽  
Operating Conditions ◽  
Test Facility ◽  
Gas Temperature ◽  
Nozzle Guide

An accelerated deposition test facility was operated with three different coal ash species to study the effect of ash composition on deposition rate and spatial distribution. The facility seeds a combusting (natural gas) flow with 10–20 micron mass mean diameter coal ash particulate. The particulate-laden combustor exhaust is accelerated through a rectangular-to-annular transition duct and expands to ambient pressure through a nozzle guide vane annular sector. For the present study, the annular cascade consisted of two CFM56 aero-engine vane doublets; comprising three full passages and two half passages of flow. The inlet Mach number (0.1) and gas temperature (1100°C) are representative of operating turbines. Ash samples were tested from the three major coal ranks: lignite, subbituminous, and bituminous. Investigations over a range of inlet gas temperatures from 900°C to 1120°C showed that deposition increased with temperature, though the threshold for deposition varied with ash type. Deposition levels varied with coal rank, with lignite producing the largest deposits at the lowest temperature. Regions of heightened deposition were noted; the leading edge and pressure surface being particularly implicated. Scanning electron microscopy was used to identify deposit structure. For a limited subset of tests, film cooling was employed at nominal design operating conditions but provided minimal protection in cases of severe deposition.

Failure Analysis of Nozzle Guide Vane of a Low Pressure Turbine in an Aero Gas Turbine Engine

2014 ◽  
Vol 14 (5) ◽  
pp. 578-587 ◽  
Author(s):  
R. K. Mishra ◽  
Johney Thomas ◽  
K. Srinivasan ◽  
Vaishakhi Nandi ◽  
Raghavendra Bhat
Keyword(s):  
Failure Analysis ◽  
Gas Turbine ◽  
Guide Vane ◽  
Low Pressure ◽  
Gas Turbine Engine ◽  
Turbine Engine ◽  
Low Pressure Turbine ◽  
Nozzle Guide Vane ◽  
Nozzle Guide

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.

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